Foundation of Information and Communication Technology

Foundation of Information and Communication Technology
NATIONAL OPEN UNIVERSITY OF NIGERIA COURSECODE:CIT701
COURSE TITLE: FoundationofInformationand
CommunicationTechnology
1
Course Code
CIT 701
Course Title
Foundation of Information and
Communication Technology
Course Writer
Mr. Musa, Abaraham Abaka
Management Information System (M.I.S) Unit,
Academic Planning Department,
Kaduna State University,
Tafawa Balewa Way,
P.M.B 2339,
Kaduna State.
Course Editor
Programme Leader
Course Coordinator
NATIONAL OPEN UNIVERSITY OF NIGERIA
2
CONTENTS
PAGE
Introduction…………………………………………….…………………………………..….3
What you will learn in this Course…….………………..……………………………………..3
Course Aims…………………………….………………..……………………………………3
Course Objectives……………………….…………………………………………………….3
Working through this Course…………….………………..…………………………….…….4
The Course Material…………………….…………………..……………………………..….4
Study Units…………………………..….……………………………………………………..5
Presentation of Schedule………….…..……………………………………………………….7
Assessment…………………….…………..…………………………………………….…….7
Tutor Marked Assignment…….…………..……………………………………………….….8
Final Examination and Grading …………..……………………………………………….….8
Course Marking Scheme…………………..………………………………………………….9
Facilitators/Tutors and Tutorials…………..………………………………….……………….9
Summary………………………………………………………………………..……………10
3
Introduction
Information is the life wire of today’s business organizations, institutions and industries.
Information and Communication Technologies (ICT) covers all advanced technologies in
manipulating and communicating information. Understanding the ICT three main
components: Information; the use of computers to transform data into information,
Communications; transmission of information through networks, Technology; the know-how
used for the transmission, will ease your understanding of this course.
This course, Foundation in Information and Communication Technology (ICT) focuses
on the way ICT is transforming the way people do business and how ICT impacts their
personal lives. The emphasis is on the way ICT is used and applied for problem solving; the
new and emerging technologies as they are being implemented in real organizations;
applications to personal and professional practice; and the challenges and opportunities of IT
in local and international business solutions.
What you will learn in this Course
The Course material has two components; this course guide and the main lecture note. This
course guide tells you briefly what the course is about, what course material you will be using
and how you can use the materials. In addition, it advocates some general guidelines for the
amount of time you are likely to spend on each unit of the course in order to complete it
successfully.
It gives you guidance in respect of your Tutor-Marked assignment which will be made
available in assignment folder. There will be regular tutorial classes that are related to the
course. It is advisable for you to attend these tutorial sessions. The course will prepare you
for the challenges you will meet in trying to build a foundation in Information and
Communication Technology, by describing the combination of traditional computer and
communication technologies and how they interrelate within the Enterprise.
4
Course Aims
The aim of this course is simply to teach you the basics in ICT and help you develop a habit
of keeping current technology trend which is a key to your success with Information and
Communication Technology.
Course Objectives
In order to achieve this aim, the course has a set of objectives. Each unit has specific
objectives which are included at the beginning of the unit. You are expected to read these
objectives before you study the unit. You may wish to refer to them during your study to
check on your progress. You should always look at the unit objectives after completion of
each unit. By doing so, you would have followed the instructions in the unit.
Bellow are the comprehensive objectives of the course as a whole. By meeting this
objectives, you should have achieved the aim of the course. Therefore, after going through
this course you should be able to:
•
Explain the principles and practices in Information and Communication Technology.
•
Identify uses, types and advantages of Databases and Computer Networks.
•
Discuss the importance and infrastructural use of Distributed Networks, the Internet
and W3.
•
Explain how Information and Communication Technology Applications are managed
by personal, enterprise and businesses, and the strategies they used to survive.
•
Know the challenges posed by Information and Communication Technology and the
provided solutions.
Working through this Course
To complete this course, you are required to read each study unit, read the textbooks and read
other materials which may be provided by the National Open University of Nigeria.
Each unit contains self-assessment exercise and at certain points in the course you would be
required to submit assignment for assessment purposes. At the end of the course there is a
final examination. The course should take you about a total of 17 weeks to complete. Bellow
you will find listed all the components of the course, what you have to do and how you
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should allocate your time to each unit in order to complete the course on time and
successfully.
This course entails that you spend a lot of time to read and practice. For easy understanding
of this course, I will advise that you avail yourself the opportunity of attending the tutorials
sessions where you would have the opportunity to compare your knowledge with that of other
people, and also have your questions answered.
The Course Material
The main components of this course are:
1. The Course Guide
2. Study Units
3. Further Reading/References
4. Assignments
5. Presentation Schedule
Study Units
The study units in this course are as follows:
Module 1
Introduction to Information Communication Technology
Unit
1:
Unit
2:
Information Communication Technology: Principles, Practices, and
Opportunities.
Essentials of Computing
Unit
3:
The System Unit and the Central Processing Unit
Unit
4:
Input Devices
Unit
5:
Output Devices
Unit
6:
Storage Devices and Memory
Module 2
Unit
7
Databases and Computer Networks
Databases
6
Unit
8:
Database Management System (DBMS).
Unit
9:
Database Queries
Unit
10:
Enterprise Databases and Data Warehouses
Unit
11
Computer Networks
Unit
12
Networking Technologies
Module 3
Distributed Networks and the Internet
Unit
13:
Communications Networks
Unit
14:
Enterprise and Wireless Communications Networks
Unit
15:
Essentials of the Internet
Unit
16:
World Wide Web
Unit
17:
Electronic Commerce and Electronic Business
Unit
18:
Launching Information Technology Applications Projects
Module 4
Managing Information and Communication Technology Applications
in the Enterprise.
Unit
19:
Creating Enterprise Applications
Unit
20:
Project Management
Unit
21:
Web Based Application
Unit
22:
Information Systems in the Enterprise
Unit
23:
Issues in Information Technology
Unit
24:
Careers in ICT.
For easy presentation of the course to you, we have divided the course into four modules of
six units each, with each module covering an important aspect of the course; Module 1
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focused on the information dissemination and the Computer System, Module 2: databases
and networking technologies, Module 3: distributed networks and the internet and Module 4:
how to mange information and communication technology applications in the enterprise and
the corresponding challenges.
In module one (1), the first unit focuses on the basic principles, practices and opportunities in
ICT. The second unit deals with the essence of computing. The third unit discusses about the
system unit (SU) and the central processing unit (CPU) acting as the brain of the computer.
The fourth unit deals with the Input devices acting as the ear and eye that feed the brain with
data to process. The fifth unit explores the Output devices; used by the computer to transmit
information to the outside world. The sixth unit discusses the Storage Devices and Memory;
that keeps information permanently and temporary, respectively.
Module two (2) is made up of unit 7 to 12, and it is mainly concerned with how data and
information are kept and shared among users. In unit 7, the components, types, uses and
development of database applications are dealt with. Unit 8 deals with the software used in
manipulating the database known as the database management system (DBMS). Unit 9 deals
with the language used for easy manipulation of data in a database known as the Query
language. Unit 10 deals with why and how data is shared within the organization. Unit 11
discusses the infrastructures used in sharing the data. Unit 12 being the last in this module
introduces you to the concept of computer networks; the inter-connection of computers, using
wires or wireless links, confined in a location or scattered around distant places for the
purpose of sharing information with ease.
Module three (3) comprises unit 13 to 18, which focuses on how computers and
communication devices are inter-connected to form extranets, intranets and internet. In unit
13, the principles of communication networks, types of network service applications, network
channels and data transport technologies were discussed. In unit 14, wireless
communications, the role of network operating system and network administration in an
enterprise were discussed. Unit 15 introduces the concept of internet, its uses, capabilities,
communication, information retrieval and differences with other networks such as Extranets
and Intranets. Unit 16 explores the World Wide Web used to connect to the internet and to
access available resource using browser software. The Web has an e-mail facility used to
transmit electronic messages over the internet. In Unit 17, the concept, advantages and
disadvantages, types and ways of buying and selling over the internet through Electronic
Commerce were discussed. Unit 18, the last unit in module three, discusses about the ICT
department, the key players and how an information system is analyzed and designed
objectively.
Module four (4) is made up of unit 19 to 24, unit 19 focuses on how to develop and launch an
ICT application in an enterprise successfully. Unit 20 deals with how to manage a project by
setting a goal, sharing responsibilities, designing a work plan and working as a team. Unit 21
deals with Web based applications; how they work, the types and advantages of technologies
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involved. Unit 22 described the types of Information System and their Characteristics, the
Competitive Strategies used by business and enterprise resource planning. Unit 23 “Issues in
Information Technology,” explores important challenges surrounding the use of ICT,
including issues of IT security, digital piracy, ethics, personal privacy and ICT reliability.
Finally unit 24 “Careers in ICT,” explores the professions in the world of IT, their required
qualifications and responsibilities to enable you build a career by adding value to you resume
and know who to handle your job.
Each unit consists of one or two weeks’ work and include an introduction, objectives, main
content (reading material), conclusion, summary, tutor-marked assignment (TMAs),
references and other resources. The unit directs you to work on exercises related to the
required reading. In general these exercises test you on the materials you have just covered or
require you to apply it in some way, hence assist you to evaluate your progress and to
reinforce your comprehension of the material. The TMAs will help you in achieving the
stated learning objectives of the individual units and of the course as a whole.
Presentation of Schedule
Your course materials have important dates for early and timely completion and submission
of you TMAs and attending tutorials. You should remember that you are to submit all your
assignments by the stipulated time and date. You should guard against falling behind in your
work.
Assessment
There are three aspects to the assessment of the course. The first is made up of selfassessment exercise, second consist of the tutor marked assignments and third is written
examinations/end of the course examination.
You are advised to do the exercise. In tackling the assignment, you are expected to apply
information, knowledge and techniques you gathered during the course. The assignment must
be submitted to your facilitator for formal assessment according to the deadline stated in the
presentation schedule and the assignment file. The work you submit to you tutor for
assessment will count for 30% of you total course work. At the end of the course you will
need to sit for a final or end of course examination of about three hours duration. This
examination will count for 70% of your total course mark.
Tutor Marked Assignment
9
The TMA is a continuous assessment component of your course. It accounts for 30% of the
total score. You will be given four (4) TMAs to answer. Three of these must be answered
before you are allowed to sit for the end of course examination. The TMAs would be given to
you by your facilitator and returned after you have done the assignment. Assignment
questions for the units in this course are contained in the assignment file. You will be able to
complete your assignment from the information and material contained in your reading,
references and study units. However, it is desirable in all degree level of education to
demonstrate that you have read and researched more into your references, which will give
you a wider view point and may provide you with a deeper understanding of the subject.
Make sure that each assignment reaches your facilitator on or before the deadline given in the
presentation schedule and assignment file. If for any reason you cannot complete your work
on time, contact your facilitator before the assignment is due to discuss the possibility of an
extension. Extension will not be granted after the due date unless there are exceptional
circumstances.
Final Examination and Grading
The end of course examination for this course will be for about two and a half hours and it
has a value of 70% of the total course work. The examination will consist of questions, which
will reflect the type of self-testing, practice exercise and tutor-marked assignment problems
you have previously encountered. All areas of the course will be assessed.
You are to use the time between finishing the last unit and sitting for the examination to
revise the whole course. You might find it useful to review your self-test, TMAs and
comments on them before the examination. The end of the course examination covers
information from all parts of the course.
Course Marking Scheme
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Assignment
Marks
Assignment 1 – 4
Four assignments, best three marks of the four
counts at 10% each -30% of course marks.
End of Course Examination
70% of the overall course marks.
Total
100% of course materials.
Facilitators/Tutors and Tutorials
There are 16 hours of tutorials provided in support of this course. You will be notified of the
dates, times and location of these tutorials as well as the name and phone number of your
facilitator, as soon as you are allocated a tutorial group.
Your facilitator will mark and comment on your assignments, keep a close watch on your
progress and any difficulties you might face and provide assistance to you during the course.
You are expected to mail your Tutor Marked Assignment (TMA) to your facilitator before
the schedule date (at least two working days are required). They will be marked by your tutor
and returned to you as soon as possible.
Do not delay to contact your facilitator by telephone or e-mail if you need assistance.
The following might be circumstances in which you would find assistance necessary, hence
you would have to contact your facilitator if:
 You do not understand any part of the study or the assigned readings.
 You have difficulty with the self-tests.
 You have a question or problem with an assignment or the grading of an assignment.
You should Endeavour to attend the tutorials. This is the only chance to have face to face
contact with your course facilitator and to ask questions which are answered instantly. You
can raise any problem encountered in the course of your study.
To gain much benefit from the course tutorials prepare a question list before attempting them.
You will learn a lot from participating actively in discussions.
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Summary
Information is an organized, meaningful and useful interpretation of data. The foundation of
Information and Communication Technology course attempts to provide you with the basic
tools, a wide variety of items and abilities used in the creation, storage and dispersal of data
and information as well as the creation of knowledge. This course explores the role of ICT in
today’s world. Today whether you start, sell, buy, invent, build, manage, or finance
companies, products, or services, you will find that a working knowledge of ICT is essential
with no exceptions. Using ICT capabilities effectively and creatively can be a key to your
success, whether you are focusing on a professional, healthcare, entrepreneurial,
manufacturing, or service career.
This course will answer basic questions such as:
•
What is Information and Communication Technology (ICT)?
•
What are the functions and uses of ICT components?
•
How are ICT applications and infrastructure managed in the Enterprise?
•
What are the importance of ICT in business and other fields?
•
Who are the Professionals and Managers of ICT?
•
What are the challenges of ICT and how were they addressed?
Apart from the academic benefit of studying this course, you will find the principles taught in
this course quite helpful in your everyday life. It is also hoped that this course will improve
your quality of decision; enable you acquire ICT skills and know how to apply it to your
environment.
Finally, I wish you success in the course and I hope that as you give your best to this course,
you will find it both interesting and useful.
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MODULE 1
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
UNIT 1:
1.0
2.0
3.0
PRINCIPLES, PRACTICES, AND OPPORTUNITIES OF
INFORMATION COMMUNICATION TECHNOLOGY
Introduction………………………….………………………………………………..2
Objectives……………………………………….…………………………………….2
Main Content…………………………………………………..………………………2
3.1
Information……………………………….……………………………………2
3.1.1 Classification of Information…………………….…………………..2
3.2
Transmission of Information…………………………………………………..3
3.3
Stages of Information Revolut ion……………………………………………..3
3.4
The Evolution of the Information Age………………………………………...4
3.5
The Characteristics of the Information Age……………….………………….4
3.6
What Is Information And Communication Technology? ..................................5
3.6.1
3.7
Concept of Information Technologies...............................................5
3.6.1.1
Computers................................................................6
3.6.1.2
Communications Networks...................................11
3.6.1.3
Know-How ………………...………..….……..…12
The Principles of Information Technology......................................................12
3.7.1 The Functions of Information Technology..........................................12
3.7.2 The Benefits of Information Technology.............................................13
3.7.3 The Opportunities of Information Technology....................................14
4.0
Conclusion...................................................................................................................14
5.0
Summary......................................................................................................................14
6.0
Tutor Marked Assignment............................................................................................15
7.0
Further Readings/References.......................................................................................15
13
1.0
INTRODUCTION
Information is the life wire of today’s business organisations, institutions and industries.
Every organisation, regardless of its size and purpose, is concerned with processing data in
order to provide current and accurate information. Employees at every level within most
organisations use various devices or tools in the performance of their everyday duties.
2.0
OBJECTIVES
•
Define Information and what are its characteristics
•
Explain the three primary components of information technology.
•
Summarise the principles of business reengineering, while emphasising the potential
benefits to people and business.
•
Discuss the types of opportunities that information technology offers to people.
3.0
MAIN CONTENT
Data refers to facts, events, activities and transactions which have been recorded. Data is the
raw material from which information is produced. When you were admitted into school your
school you gave the school information about yourself. You probably wrote it on a form that
must have been supplied to you. The information that you gave is a set of facts about
yourself. The school now has some data on you.
3.1
INFORMATION
“It will be sunny tomorrow;” “There are some men in the field”. “The turkey gave birth to a
lion day before yesterday.” These statements convey to you something. It does not matter
whether they are true or false, each is telling a story. The story being passed to you is what is
known as information. Therefore Information is news passed to you either orally or in
written. If the information given is true no matter who is giving it or when it is given it is
said to be a fact or data.
3.1.1 CLASSIFICATION OF INFORMATION
Information could be classified based on the forms in which information can exist, the time of
occurrence, and the frequency of occurrence.
•
Information classified based on form of existence include, written, oral, visual, and
sensory.
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3.2
•
Information classified based on time of occurrence could be historical, present, and
future.
•
While information based on frequency of occurrence are those that are continuously,
hourly, daily, weekly, monthly, and annually.
TRANSMISSION OF INFORMATION
After receiving information the question of how to disseminate it now arises. Ideally for an
item to be a piece of information, it has to be passed from one person to another and from one
place to another. Information could be passed through an ancient or a modern method as
summarised in the Table 1.1.
Table 1.1
Methods of Spreading Information.
Old methods of spreading Information
New methods of spreading Information
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Oral
Town crier
Beating drums
Lighting fire
Drawing diagrams representations
/symbols
Writing
Typing
Printing
Telephone
Telex
Radio
Television
Fax
Satellite
Computer
E-mail
Source: (Wikipedia, 2006).
3.3
STAGES OF INFORMATION REVOLUTION
The oldest evidence of writing by man so far consists of clay tablets discovered at Sumer in
Mesopotamia about 3000BC. These tablets contain records of grains received from, or issued
to, individuals at a temple store. Since then the society has seen five distinct stages of
information revolution. These stages are:
•
Invention of language
•
Invention of printing
•
Invention of mass media particularly radio and television
•
Invention of computer
•
Link-up of computers with communications devices and the development of the
Internet.
15
3.4
THE EVOLUTION OF THE INFORMATION AGE
The evolution of the information age is classified into three basic groups:
•
Agricultural Age: The period up to the 1800s, when the majority of workers were
farmers whose lives revolved around agriculture.
•
Industrial Age: The period from the 1800s to 1957, when work processes were
simplified through mechanisation and automation.
•
Information Age: The period that began in 1957, in which the majority of workers
are involved in the creation, distribution, and application of information.
•
Knowledge Workers: Workers involved in the creation, distribution, and application
of information.
Table 1.2
The Evolution of Information Age.
Characteristics
Time Period
Majority of Workers
Partnership
Principal Tool
Agricultural Age
Pre 1800
Farmers
People and Land
Hand Tool
Industrial Age
1800 - 1957
Industrial Workers
People and Machine
Machine
Information Age
1957 - Present
Knowledge Workers
People and People
Information
Technology
Source: (Senn, 2004).
3.5
THE CHARACTERISTICS OF THE INFORMATION AGE
•
An information-based society in which more people work at handling information
than at agriculture and manufacturing combined.
•
Businesses depend on information technology to get their work done.
•
Work processes are being transformed to increase productivity.
– Work Processes: The combination of activities that workers perform, the way
they perform those activities, and the tools they use.
– Productivity: The relationship between the results of an activity (output) and
the resources used to create those results (inputs).
– Effectiveness: The extent to which desirable results are achieved.
•
Information technology provides the means to rethink / recreate / reengineer
conventional business processes.
– Reengineering: The reshaping of business processes to remove barriers that
prohibit an organisation from providing better products and services and to
help the organisation capitalise on its strengths.
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– Business Processes: Collections of activities, often spanning several
departments that take one or more kinds of input and create a result that is of
value to a company’s customers.
•
Success in business is largely determined by the effectiveness with which information
technology is used.
•
Information technology is embedded in many products and services.
•
Reengineering efforts to attain greater productivity:
–
Industrial Age - Division of Labour: Separation of work process into component
task, with different workers specialising in each of the tasks.
–
Information Age – Teamwork, Interconnection, and Shared Information.
3.6
WHAT IS INFORMATION AND COMMUNICATION TECHNOLOGY?
Information and communication technologies (ICT) is an umbrella term that covers all
advanced technologies in manipulating and communicating Information. The term is
sometimes used in preference to Information Technology (IT) or "InfoTech". It is
sometimes said to have been coined by Jim Domsic of Michigan in November 1981, to
modernise the outdated phrase "data processing".
Information Technology means the processing and distribution of data using computer
hardware and software, telecommunications, and digital electronics. This unit will give us a
background view on Information Communications Technology (ICT).
3.6.1
CONCEPT OF INFORMATION AND COMMUNICATION
TECHNOLOGIES (ICT)
Focusing on the three words behind ICT:
•
INFORMATION
•
COMMUNICATIONS
•
TECHNOLOGY
We can deduce that ICT is concerned with the storage, retrieval, manipulation, transmission
or receipt of digital data. Importantly, it is also concerned with the way these different uses
can work with each other in business.
•
The nature of information (the "I" in ICT) covers areas such as the meaning and value
of information; how information is controlled;
‐ Management of information - this covers how data is captured, verified and
stored for effective use; the manipulation, processing and distribution of
information; keeping information secure; networks design to share information.
17
‐ Information systems strategy - this considers how ICT can be used within a
business or organisation as part of achieving goals and objectives.
•
The C part of ICT refers to the communication of data by electronic means, usually
over some distance. This is often achieved via networks of sending and receiving
equipment, wires and satellite links.
•
The T part of ICT refers to the more recent, and fast-growing range of digital
technologies which allow people and organisations to communicate and share
information digitally
ICT three main components are
–
Computers; used to process data into information,
–
Communications networks; transmission of information,
–
Know-how; the technology used for the transmission
Figure 1.1
The Forces of Information Technology.
Source: (Senn, 2004).
3.6.1.1 Computers
A computer is an electronic system that can be instructed to accept, process, store, and
present data and information. It is made up of two component parts: hardware and software.
–
Hardware: The computer and its associated equipment.
–
Software: The general term for a set of instructions that controls a computer or a
communications network.
18
–
Program: A set of instructions that directs a computer to perform certain tasks
and produce certain results.
–
System: A set of components that interact to accomplish a purpose.
–
Data: Raw facts, figures, and details.
–
Information: An organised, meaningful, and useful interpretation of data.
–
Knowledge: An awareness and understanding of a set of information and how that
information can be put to the best use.
–
Information System: A business information system designed to produce the
information needed for successful management of a structured problem, process,
department, or business.
Computers come in four sizes:
– Microcomputers
– Midrange computers
– Mainframes
– Supercomputers
•
Microcomputers: A relatively compact type of computer, the most common of all,
easily outsells all other types of computers annually for use in schools, business and at
homes. There are five types of Microcomputers:
–
Desktop Computers:
–
Tower Systems
–
Laptop Computer
–
Notebook Computer:
–
Palmtop computers:
19
Desktop Computers: These are the type of microcomputers whose monitor is placed
on top of the system’s unit.
Figure 1.2
Desktop Microcomputers.
Source: (Google Images, 2009).
Tower Systems: These are the type of microcomputers whose system’s units sits
beside the computer monitor.
Figure 1.3
A tower system.
Source: (Google Images, 2009).
20
Laptop Computer: This describes the type of microcomputers whose miniature size
makes it possible for a user to place on top of his/her lap for usage.
Figure 1.4
A Laptop computer.
Source: (Google Images, 2009).
Notebook Computer: This describes the type of microcomputers whose size can be
compared to that of a notebook.
Figure 1.5
A Notebook computer.
Source: (Google Images, 2009).
21
Palmtop computers: This describes the type of microcomputers a user can place on
top of his palms for usage, and can as well easily carry it around. It’s also called
Personal Digital Assistant (PDA).
Figure 1.6
A Psion Series 3mx Palmtop and mini Palmtop computers.
Source: (Google Images, 2009).
•
Midrange computers and Mainframes: A computer uses to interconnect people and
large sets of information. More powerful than a microcomputer, the minicomputer is
usually dedicated to performing specific functions. Examples are IBM 360/370
systems, NCR V-8800 system.
•
Supercomputers: The most powerful of all computers, supercomputers were designed
to solve problems consisting of long and difficult calculations. Example A Cray x-mp
Super Computer
•
Minicomputers: These were developed in the 1970s for specialised tasks (i.e. they
are special purpose computers). They are smaller and less powerful and even less
expensive than mainframes. Examples include PDP 11, VAX 750/6000, NCR 9300,
DEC, HEWLETT PACKARD 3000, IBM system 38 and MV400.
22
Figure 1.7
A typical Business System.
Source: (Senn, 2004).
3.6.1.2
COMMUNICATIONS NETWORKS
Communications Network can be defined as a set of locations, or nodes, consisting of
hardware, programs, and information linked together as a system that transmits and receives
data and information.
–
Communication: The sending and receiving of data and information over a
communications network.
–
Data Communication: The transmission of data and information through a
communications medium.
23
3.6.1.3
KNOW-HOW
Know-how is the capability to do something well. Information technology know-how
consists of:
3.7
–
Familiarity with the tools of IT; including the Internet
–
Possession of the skills needed to use these tools
–
An understanding of when to use IT to solve a problem or create an opportunity
THE PRINCIPLES OF INFORMATION TECHNOLOGY
A principle is a fundamental rule, guideline, or motivating idea that, when applied to a
situation, produces a desired result. ICT’s great usefulness is an aid in solving problems,
unlocking creativity, and making people more effective than they would be if they did not
apply ICT to their activities.
3.7.1 THE FUNCTIONS OF INFORMATION TECHNOLOGY
Information Technology is made up of nine (9) major functions, namely; Capture, Verifying,
Processing/Manipulation,
Storage,
Retrieval,
Data
Update,
Reproducing,
Transmit/Communication, and Generation.
• Capture: The process of compiling detailed records of activities. This could be by
recording of data from an event or occurrence, in some form such as sales slips, personnel
forms, purchase orders, meters, course registration forms, etc.
• Verifying: Is the operation for checking or validating of data to ensure it was captured
and recorded correctly.
• Processing/Manipulation: The process of converting, analysing, computing, and
synthesising all forms of data or information.
–
Classifying: Is the operation for placing data elements into specific categories
such as size, type, customer, etc.
–
Arranging (Sorting): This is placing data elements in a specified or predefined
sequence.
–
Calculating: This entails the arithmetic and /or logical manipulation of data
e.g. comput ations to derive employee’s pay, customer’s bills etc.
–
Summarising: Reducing data in logical sense. For example the school
principal may only be interested in the total amount of the development levies
collected out of the total school fees.
• Storage: This entails placing data onto some storage media such as magnetic disk, etc
where it can be retrieved when needed.
• Retrieval this entails searching out and gaining access to specific data elements from the
medium where it was stored for further processing or for transmission to another user.
24
• Data Update: This involves making changes to the stored data. Such changes may be to
insert new records or modify some data items of the existing record. However, this is
usually the exclusive preserve of a class of authorised data users
• Reproducing: This entails duplicating data from one medium to another or into another
position in the same medium. Example a file of data stored on a magnetic disk may be
reproduced onto another disk or onto a magnetic tape for further processing or for
security reasons.
• Transmission/Communication: The computer process of distributing information over a
communications network. This entails transfer of data from one place to another e.g. data
can be transferred from a device to a user in form of a report or a display on the screen of
a computer controlled terminal.
– Electronic Mail, or E-Mail
– Voice Messaging, or Voice Mail
• Generation: The process of organising information into a useful form, whether as
numbers, text, sound, or visual image.
3.7.2 THE BENEFITS OF INFORMATION TECHNOLOGY
The benefits of ICT are Information processing speed, consistency, accuracy and reliability as
illustrated in the diagram bellow.
Figure 1.8
The Benefits of Information Technology.
Source: (Senn, 2004).
25
3.7.3 THE OPPORTUNITIES OF INFORMATION TECHNOLOGY
•
Helping People
•
Solving Problems
– Problem: A perceived difference between an existing condition and a desired
condition.
– Problem Solving: The process of recognising a problem, identifying
alternatives for solving it, and successfully implementing the chosen solution.
Information technology is all around us, improving our lives especially in areas such as:
•
Media
– Print (Newspaper, Magazines, Posters and Billboard)
– Electronic (Television, Radio and Internet)
•
4.0
Education, Training, Entertainment, Shipping, Paperwork, Money and Investments,
Agriculture, Taxation and Accounting, Health and Medicine, Manufacturing,
Journalism, Energy, and Sports.
CONCLUSION
Organisations today now require tools that will enable them to get relevant information easily
and on time. The responsibilities of using Information and Communication Technology (ICT)
is to get people informed, make proper use of the technology and protect the information
against unauthorised access by hackers and unethical users.
5.0
SUMMARY
The concepts, methods and applications involved in ICT are constantly evolving on
an almost daily basis. A good way to think about ICT is to;
•
Consider all the uses of digital technology that already exist to help
individuals, businesses and organizations use information,
•
Know the technique used to store, retrieve, manipulate, transmit or receive
information electronically in a digital form,
•
Believe information and communication technology (ICT) has truly turned the
world into a global village.
26
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What is Information and Communication Technology? List its three main
components.
b. List five ways by which information can be transmitted.
c. Name the three stages of information evolution.
d. Why do we need computers to process data into information?
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
•
Wikipedia Table. (n.d). Retrieved May 2006, from http://www.wikipedia.org.
27
MODULE 1
UNIT 2:
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
ESSENTIALS OF COMPUTING
1.0
Introduction..................................................................................................................17
2.0
Objectives.....................................................................................................................17
3.0
Main Content................................................................................................................17
3.1
Hardware (Computer Hardware or Devices)....................................................18
3.2
Software............................................................................................................20
3.3
Information…………………………………………………….......................23
3.4
IT users and Professionals.…………………………………….......................23
3.5
IT Procedures…………………………………...............................................24
3.6
An Introduction to Systems.............................................................................25
4.0
Conclusion....................................................................................................................26
5.0
Summary......................................................................................................................26
6.0
Tutor Marked Assignment (TMA)...............................................................................26
7.0
Further Reading/References.........................................................................................26
28
1.0
INTRODUCTION
In Unit 1, you were introduced to the concept of ICT. In this unit you will be looking at the
basic components of a computer system, their various uses and the people responsible for
acquiring, developing, maintaining, or operating the hardware associated with computers and
communications networks to process these data.
2.0
3.0
OBJECTIVES
•
Know the difference between a Computer and a Comput er System.
•
Identify the four categories of hardware.
•
Discuss the relationship between hardware and software.
•
Distinguish between the users of information technology and IT professionals.
MAIN CONTENT
Computer: An electronic system that can be instructed to accept data as an input, process it
and gives a result as an output, and in turn stores the data for retrieval in the long run is a
computer.
Computer System: The computer system is made up of two components parts (Hardware and
Software). These components integrate and interrelate. They do this independently by
interacting together to perform the basic operations of the computer system. These
components are linked together via cords and interface connectors, except for the user who is
the people ware, the processes (procedures), and information (processed data).
– Hardware
–
Software (Programs)
– Information
– People (People Ware)
– Procedures
29
Figure 2.1
The five Components of a Computer System.
Source: (Senn, 2004).
3.1
HARDWARE (COMPUTER HARDWARE OR DEVICES)
The hardware component is the physical component of a computer system i.e. those parts of
the computer that can be touched, felt and seen physically. More or less, the hardware
component consists of a combination of different devices which play specific roles in the
operation of the computer system.
These devices that make up the hardware are classified into one of four units depending on
the role they play in the computer system as follows:
•
•
•
•
Input devices (Keyboard, Mouse, Scanner, Camera etc)
Output devices (Printers, plotters etc)
Storage (Hard disk, floppy disk, CD, flash drives etc)
System unit (SU).
(Note that the above mentioned hardware components will be discussed in later units.)
30
Figure 2.2
The four categories of Hardware and commonly used media.
Source: (Senn, 2004).
Storage devices
System Unit
Figure 2.3 Four categories of Hardware.
Source: (Senn, 2004).
31
3.2
SOFTWARE
Software is the general term for the set of programs and data, which direct the hardware on
what to do. A program is an independent set of instructions, which work to direct the
hardware to perform specified tasks. In other words, software’s are set of logical instructions
that put the hardware to tasks assigned to it. Softwares are subdivided into Application and
System software.
•
System software focuses on handling technical details.
•
Application software focuses on completing specific tasks or application.
a.
System Software
These are programs expressly designed to make the computer more efficient and flexible as a
human tool. System software works with end users, application programs, and computer
hardware to handle many details relating to computer operations.
Not a single program but a collection or system of programs. These programs handle
hundreds of technical details with little or no user intervention. Four kinds of system
programs are operating systems, utilities, device drivers, and language translators.
•
Operating Systems (OS): coordinates resources, provide an interfaces between users
and the computer, and run programs.
•
Utility (service programs) performs specific tasks related to managing computer
resources.
•
Device Drivers: This is a program developed by the manufacturer of a device or
computer hardware component to make the devices work on different software
platforms. The examples of such devices are network interface cards (NIC), sound
cards, printers, and other computer peripherals.
•
Language Translator: converts programming instructions written by programmers
into a language that computers can understand and process.
Operating Systems, also known as software environments or platforms, consist of a
collection of programs to handle technical details.
Functions
Operating systems perform a variety of functions. These functions can be classified into three
groups:
•
Resources manager – coordinates and monitor all computer resources.
•
Provides user interface – provides interface between users, application programs,
and computer hardware. Character based interface uses written commands. Graphical
user interface (GUI) uses graphical elements.
32
•
Applications control – load and run programs. It has the ability to switch between
applications stored in memory. Current program run in foreground. Others run in
background.
Categories
There are hundreds of operating systems but only three basic categories:
•
Embedded for handheld computers and small devices
•
Network (NOS) control and coordinate computers on a network. Network server
coordinates all network communication.
•
Stand-alone (desktop) for desktop and notebook computers; called client operating
systems in networked environment.
Propriety operating systems are owned and licensed by a corporation; non proprietary are
free and called open source programs.
b.
Application software: There are two categories:
– Basic applications (general-purpose applications, productivity applications)
are widely use.
– Specialised applications (special-purpose applications) are more specialised.
Common Features
Common features of most application programs include:
– User interface – most have graphical user interface (GUI) that displays icons.
Graphic User Interface (GUI) is a link to an operating system that allows users to
use icons rather than command words to start processing. An Interface is the
means by which a person interacts with a computer.
– Windows – rectangular areas that can contain documents, programs, and
messages.
– Menus – present commands listed on the menu bar; use pull-down (drop
down) menus. Help menu provides access to online assistance.
– Dialog box – provides additional information or requests user input.
– Toolbars – contains buttons and menus; standard toolbar common to most
applications
Some of the most popular applications software’s are data management packages, spread
sheets, graphics packages; word-processing packages, communication packages; presentation
software and integrated packages. We now look at some application software’s in detail.
33
Software Package: An application that focuses on a particular subject, such as word
processing, and is sold to businesses and the general public. Examples are:
•
Spreadsheet: A table of columns and rows used by people responsible for tracking
revenues, expenses, profits, and losses.
•
Word-processing (WP) Program: A program that allows the user to enter, change
(edit), move, store, and print text information.
•
Desktop Publishing (DTP) Program: A program that combines text and imagehandling features with document-design capabilities.
•
Graphics Presentation Program: A program that translates data into visual
representations using charts, graphs, and map.
•
Photo Editing Program: A program used to touch up, remove, or add features to a
digital version of photographs.
•
Illustration Program: A program in which the computer screen becomes a drawing
board on which artists translate their ideas into visual form.
•
Database Management Program: A program that makes it possible for users to
manage the data in ways that increase accessibility and productivity.
– Database: A collection of data and information describing items of interest to an
organisation.
•
Browser: Client computer program designed to locate and display information on the
World Wide Web.
•
Information System or Management Information System (MIS): A business
information system designed to produce the information needed for successful
management of a structured problem, process, department, or business.
•
Transaction Processing: A shared business information system that uses a
combination of information technology and manual procedures to process data and
information and to manage transactions.
•
Computer Programming Language: A series of commands or codes that a computer
can translate into the electronic pulses that underlie all computing activities.
•
Utility Program (Utilities): Special programs used to perform tasks that occur
repeatedly using processing.
•
Custom Software: Software written specially for a particular business.
– Documentation: An instruction manual that accompanies software. Also, a
technical, detailed written description of the specific facts of a program.
34
3.3
INFORMATION
•
Information: An organised, meaningful, and useful interpretation of data.
– Data
– Text
– Sound
– Images
•
Data: Raw facts, figures, and details.
•
Spoken Information: Information that is conveyed by sound.
Figure 2.4
The four components of information.
Source: (Senn, 2004).
3.4.
IT USERS AND PROFESSIONALS
The following are the users of IT resources:
– Hands-on users: these are the people who use computers or communications systems
directly, interacting with them to enter data, do processing, store and retrieve
information, transmit details, or produce output.
– Indirect end users: these individuals do not directly operate a computer but benefit from
IT as the recipients of reports, electronic messages, communications, or multimedia
presentations.
35
– User managers: people who have supervisory responsibility for activities that involve or
are affected by IT are known as user managers.
– Senior managers: these managers evaluate the organisation’s dependence on IT and
identify the problems that could arise if appropriate operating procedures are not
established or followed.
Information Technology Professional is a person who is responsible for acquiring,
developing, maintaining, or operating the hardware associated with comput ers and
communications networks. They are:
–
Programmers: write codes using programming languages to solve problems.
–
Systems Analysts: work with users to determine the requirements an application must
meet.
–
System Designers: they formulate application specification and design the features of
custom software.
–
Web Designers: these are specialists who focus primarily on developing applications
for the internet and the World Wide Web.
–
Project Managers: coordinate the development of a project and manage the team of
programmer / analyst.
–
Network Specialists: design, operate, and manage computer communications
networks, including networks that interconnect with the internet.
–
Trainers: work with end users, helping them to become comfortable with and skilled
at using hardware and software.
–
Computer Operators: oversee the operations of computers in data centres. They also
perform support activities, such as starting applications, loading magnetic tapes, and
any other job that will ensure the smooth operation of the computer facilities.
The above professions will be discussed in details in module four under careers in IT and
certifications.
3.5
IT PROCEDURES
A Procedure is a step-by-step process or a set of instructions for accomplishing specific
results. These are: Operations, Backup and Recovery, Security, Development.
36
Figure 2.5
The four types of procedures.
Source: (Senn, 2004).
•
Operations Procedure: A procedure that describes how a computer system or
application is used, how often it can be used, who is authorised to use it, and where
the results of processing should go.
•
Backup Procedure: A procedure that describes how and when to make extra copies
of information or software to protect against losses.
•
Recovery Procedure: An action taken when information or software must be restored.
•
Security Procedure: A procedure designed to safeguard data centres, communications
networks, computers, and other IT components from accidental intrusion or
intentional damage.
•
Security Software: Software that is designed to protect systems and data.
•
Development Procedure: A procedure that explains how IT professionals should
describe user needs and develop applications to meet those needs.
3.6
AN INTRODUCTION TO SYSTEMS
A System is a set of components that interact to accomplish a purpose.
•
Single-User System (Personal Computer): An IT system used by only one person. A
system that stands alone and is not interconnected with other companies or shared by
other people.
•
Multi-user System: A communication system in which more than one user share
hardware, programs, information, people, and procedures.
37
– To share a computer
– To share hardware
– To share software
– To share information
– To share communications
4.0
CONCLUSION
A computer is a device used in computing data into information. It can be used as a stand
alone system or as a communication system comprising of five components, namely:
hardware, programs, information, people, and procedures. The components interact with each
other to achieve a business set goal.
5.0
SUMMARY
In this unit, you learnt that while hardware and software are the essential components of
computing, the real reason for using them is to produce the information that people need. The
information processing and information handling functions of IT are the means by which
these components deliver useful results to their users.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. List the four categories of hardware with examples.
b. Define an operating system and an application program.
c. Define four OS you know
d. Define the four kinds of Systems program you know.
7.0
FURTHER READING/REFERENCES
•
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
•
Meyers, M. (2007). A+ Certification Tutorial C.D (Session 8).
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 15, 2009, from
http://www.jegsworks.com.
38
MODULE 1
UNIT 3:
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
THE SYSTEM UNIT AND THE CENTRAL PROCESSING UNIT
1.0
Introduction..................................................................................................................28
2.0
Objectives.....................................................................................................................28
3.0
Main Content...............................................................................................................28
3.1
The System Unit...............................................................................................28
3.2
The Processor...................................................................................................28
3.2.1 Functions of the Central Processing Unit (CPU) ................................29
3.2.2 Processor Chips...........................................………….........................29
3.2.3 The Processing Sequence.....................................................................31
3.2.4 Processor Speed...................................................................................32
3.2.4.1
Determining Processor Speed......................................32
3.3
Ports..................................................................................................................34
3.4
Universal Serial Bus (USB) ............................................................................34
3.5
Add-In Boards..................................................................................................34
3.6
Plug And Play...................................................................................................35
4.0
Conclusion....................................................................................................................36
5.0
Summary......................................................................................................................36
6.0
Tutor Marked Assignment............................................................................................36
7.0
Further Readings/References.......................................................................................36
39
1.0
INTRODUCTION
In Unit 2, you read about the over-view of a computer system (Hardware and Software types)
and its various components. In this unit you will read about the Computer System Unit which
serves as the brain and the centre of the computer activities.
2.0
OBJECTIVES
At the end of this unit, you should be able to:
•
Describe the components of a System Unit and the major functions of the central
processing unit (CPU).
•
Identify the components of the CPU.
•
List and explain the four determinants of processor speed.
•
Describe eight ways of increasing processing and computer speed.
3.0
MAIN CONTENT
In its general interpretation, a system is a collection of inter-related parts, working together to
achieve a common goal. For our purpose however, a system shall be considered as a set of
inter-relating elements responding to input to produce output.
3.1
THE SYSTEM UNIT
The System Unit is the hardware unit that houses a computer’s processor, ports, power
supply, casing, motherboard and add-in boards and memory chips (Memory will be discussed
in unit 6).
3.2
THE PROCESSOR
Central Processing Unit (CPU)
Central Processing Unit (CPU) or Processor is the computer hardware that executes program
instructions and performs the computer’s processing actions. It is made up of the following
components housed in the Computer System Unit:
•
Integrated Circuits/Chip/Microchip: A collection of thousands or millions of
transistors placed on a small silicon chip.
•
Transistor: An electrical switch that can be in one of two states: open or closed.
•
Integrating: The process of packing more transistors onto a single chip.
40
•
Control Unit: The part of the CPU that oversees and controls all computer activities
according to the instructions it receives.
•
Instructions: Detailed descriptions of the actions to be carried out during input,
processing, output, storage, and transmission.
•
Arithmetic/Logic Unit (ALU): The part of the CPU that performs arithmetic and
logical operations.
– Arithmetic Operations: Addition, Subtraction, Multiplication, and Division.
– Logical Operations: Greater Than (>), Less Than (<), Equal To (=)
3.2.1 FUNCTIONS OF THE CENTRAL PROCESSING UNIT (CPU)
The Central Processing Unit (CPU): is known to be the brain and the computational
unit of the System Unit (SU). It performs the following major functions;
– Coordinating the activities of all units or devices associated with the
comput er system.
– Accepting and executing instructions to cause the computer system unit to
perform tasks.
3.2.2 PROCESSOR CHIPS
Microprocessor is the smallest type of processor, with all of the processing capabilities of the
control unit and ALU located on a single chip.
•
Evolution of Intel Pentium Family of Microprocessors
Table 3.1 Evolution of Intel Pentium Family of Microprocessors
NAME
DATE
INTRODUCED
TRANSISTORS
CLOCK SPEED
UPON
INTRODUCTION
DATA WIDTH
MIPS
8080
1974
6,000
2MHz
8bits
0.64
8088
1979
29,000
5MHz
16bits, 8bits
0.33
80286
1982
134,000
6MHz
16bits
1
80386
1985
275,000
16MHz
32bits
5
80486
1989
1,200,000
25MHz
32bits
20
Pentium
1993
3,100,000
60MHz
32bits,
bus
41
64bits 100
Pentium II
1997
7,500,000
233MHz
32bits,
bus
64bits NA
Pentium III
1999
9,500,000
450MHz
32bits,
bus
64bits NA
Pentium 4
2000
42,000,000
1.5GHz
32bits,
bus
64bits NA
Source: (Senn, 2004).
•
Intel Microprocessors
– Intel Celeron Processors (R, M, Duo Core, 2Duo Core)
– Intel Pentium-M Processors
– Intel Celeron-M Processors
– Intel Xeon Processors
– Intel Itanium Processors
•
Evolution of Microprocessors for Macintosh Computers
Table 3.2 Evolution of Microprocessors for Macintosh Computers
NAME
DATE INTRODUCED
CLOCK SPEED UPON
INTRODUCTION
DATA
WIDTH
Motorola MC 68000
1982
8MHz
16
Motorola MC 68020
1984
16.7 MHz
32
Motorola MC 68030
1987
20 MHz
32
Motorola MC 68040
1989
25 MHz
32
PowerPc 603
1994
120 MHz
64
PowerPc 620
1994
133 MHz
64
PowerPc 750
1997
233 MHz
64
PowerPc 64
1999
500 MHz
64
PowerPc 64 with Velocity 2002
engine
1GHz
128
PowerPc G5
2GHz
128
2003
Source: (Senn, 2004).
42
•
Other Microprocessor Chips
–
AMD
–
Digital Equipment Corp.
–
Mercury
–
Hewlett-Packard
–
MIPS Technologies
–
Sun Microcomputers
3.2.3 THE PROCESSING SEQUENCE
•
Machine Cycle: The four processing steps performed by the control unit: fetch,
decode, execute, and store.
Figure 3.1
The Machine Circle
Source: (Senn, 2004).
43
•
Instruction Cycle (I-cycle): The first two steps of the machine cycle (fetch and
decode), in which instructions are obtained and translated.
•
Execution Cycle (E-cycle): The last two steps of the machine cycle (execute and
store), which produce processing results.
•
Register: A temporary storage area in the processor that can move data and
instructions more quickly than main memory can, and momentarily hold the data or
instructions used in processing as well as the results that are generated. There are four
types:
–
Storage Registers
–
Address Registers
–
Accumulators
–
General-Purpose Registers
3.2.4 PROCESSOR SPEED
•
Millisecond: One thousandth of a second
•
Microsecond: One millionth of a second.
•
Nanosecond: One billionth of a second.
•
Picoseconds: One trillionth of a second.
•
Millions of Instructions per Second (MIPS): The number of instructions the
processor can execute per second – a measure of processor speed.
•
Megaflops: Millions of floating point operations per second – a measure of how many
detailed arithmetic calculations the computer can perform per second.
3.2.4.1
DETERMINING PROCESSOR SPEED
In determining Processor Speed, four elements are considered:
– System Clock
– Bus Width
– Word Size
– Available Memory (will be discussed in Unit 4)
•
System Clock: A circuit that generates electronic impulses at a fixed rate to
synchronise processing activities.
44
– Megahertz (MHz): Millions of electric pulses per second – a measure of a
computer’s speed.
– Gigahertz (GHz): Billions of pulses per second
•
Bus Width
– Input/Output (I/O) bus: A bus (electronic circuit) that moves data into and out
of the processor.
– Data Bus: A bus that moves data between the central processor and memory.
•
Word Size
– Word: The number of bits a computer can process at one time.
Figure 3.2
The two types of BUS
Source: (Senn, 2004).
•
Cache Memory: A form of high-speed memory that acts as a temporary
holding/processing cell.
Other factors include:
• Coprocessors: A special-purpose chip mounted on a processor board; it is designed to
handle common functions quickly and efficiently.
•
Accelerator Boards: An add-in circuit board that increases a computer’s processing
speed.
•
Reduced Instruction Set Computer (RISC)
–
Complex Instruction Set Computing (CISC): A computing instruction set that
moves data to and from main memory so often that it limits the use of
registers.
45
–
Microcode: The instructions that coordinate the execution of the instructions
to move data and from memory.
–
Reduced Instruction Set Computing (RISC): A computing instruction set that
takes data for the execution of an instruction only from registers.
•
Pipelining: A computer starts processing a new instruction as soon as the previous
instruction reaches its next step in the processing cycle.
•
Parallel Processing: Processing in which a computer handles different parts of a
problem by executing instructions simultaneously.
– Sequential Processing: Processing in which the execution of one instruction is
followed by the execution of another.
– Single Instruction/Multiple Data (SIMD) method: A parallel-processing
method that executes the same instruction on many data values
simultaneously.
– Multiple Instruction/Multiple Data (MIMD) method: A parallel-processing
method that connects a number of processors that run different programs or
parts of a program on different sets of data.
•
3.3
Grid and Cloud Computing: A process that harnesses idle time on computers and
then uses them to provide processing for an application that needs more speed and
capability than may be available on a single computer, or even on a supercomputer.
PORTS
•
Port: A connector through which input/output devices can be plugged into the
computer.
•
Expansion Slot: A slot inside a computer that allows a user to add an additional
circuit board.
3.4
UNIVERSAL SERIAL BUS (USB)
•
3.5
Universal Serial Bus (USB): A general purpose port that can connect up to 128
devices, and also hot swappable, meaning that devices can be plugged in or
unplugged without having to shut down or reboot the system.
ADD-IN BOARDS
•
Add-in Boards: A board that can be added to a computer to customise its features and
capabilities.
46
Table 3.3 Types of Add-In Boards for Microcomputers
BOARD FUNCTION
DESCRIPTION
Accelerator Board
Increases speed of Computer
Controller Board
Allows different printers and storage devices to be attached to
computer
Coprocessor Board
Include special chips that speed up the system’s overall processing
capabilities
Display Adaptor Board
Permit the use of computer displays by providing interaction with
the computer board
Fax Modem Board
Enables the computer to send and receive facsimile images, data
and information
Memory expansion
Board
Extents the computer’s memory capacity by adding additional
sockets for memory chips
Network interface
Board
Enable the computer to be connected to a Local Area Network
(LAN)
SCSI adaptor
Provides an interconnection for a variety of peripheral devices,
including scanners, CD ROM Units, and DVD players and
recorders. Also interconnects disk drives and scanners using a
SCSI interface rather than using the more common IDE or USB
interfaces
Sound Board
Contains chips and circuitry that translates data and information
into sound output including music, permits connection of speakers
to computers.
TV-tuner Board
Enable computers to receive television signals
Video Capture Board
Enable the computer to capture full motion colour video and
accompanying sound for processing and storage.
Voice Board
Provide the capability to translate stored data and information into
spoken output.
Source: (Senn, 2004).
3.6
PLUG AND PLAY
•
Plug and Play: The ability to install devices into a computer when the computer itself
makes any necessary internal adjustments.
47
4.0
CONCLUSION
The System Unit is more or less synonymous with the computer because it represents the
processing capability, which is unique to Computers. Generally speaking, a computer system
is recognised by the type and nature of its system unit (SU).
5.0
SUMMARY
In this unit, we learnt that the system unit housed some important components which play a
great role in the purchase of a computer system.
•
The processor - controls operations and performs arithmetic and logical operations.
•
The memory - serves the purpose of storage (holding data and instruction) and also
used to boot the computer system.
•
Expansion Slots-allows external devices to connect and expand a computer
capabilities.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. List the four elements to be considered when determining processor speed?
b. What are the functions of the Central Processing Unit (CPU)?
c. What is the difference between the System Unit and the Central Processing Unit?
d. Define Grid Computing?
7.0
FURTHER READING/REFERENCES
•
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
•
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
48
MODULE 1
UNIT 4:
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
INPUT DEVICES
1.0
Introduction..................................................................................................................38
2.0
Objectives.....................................................................................................................38
3.0
Main Content ...............................................................................................................38
3.1
Interaction with Computers Using Input Devices............................................38
3.1.1 Keyboard..............................................................................................38
3.1.2 Terminal...............................................................................................39
3.1.3 Scanners...............................................................................................40
3.1.4 Optical Character Recognition (OCR) ................................................41
3.1.5 Digitisers..............................................................................................41
3.1.6 Pointing Devices..................................................................................42
3.1.7 Digitising Table....................................................................................45
3.1.8 Digital Camera.....................................................................................46
3.1.9 Digital Video Camcorders....................................................................46
3.1.10 Voice and Sound Input Devices...........................................................47
3.1.11 Bar Code ..............................................................................................47
3.1.12 Wand....................................................................................................48
3.1.13 Multimedia...........................................……………............................48
3.2
The Purpose of the Mouse................................................................................49
4.0
Conclusion....................................................................................................................49
5.0
Summary......................................................................................................................49
6.0
Tutor Marked Assignment...........................................……………............................49
7.0
Further Readings/References.......................................................................................49
49
1.0
INTRODUCTION
In Unit 3, you learnt about the system unit is the computer’s brain. In this unit you will learn
about the input devices which are the eyes and ears of the computer. The computer would be
useless if you could not interact with it, because the machine will not receive instructions for
onward processing.
2.0
OBJECTIVES
At the end of this unit, you should be able to:
3.0
•
Identify the six special key groups on a standard computer keyboard
•
Name the functional keys on a keyboard
•
Describe the purpose of a mouse and the role it plays in computing
•
Identify other input devices apart from the mouse and keyboard
MAIN CONTENT
An Input is the data or information entered into a computer or the process of entering data or
information into the computer for processing, storage and retrieval, or transmission.
3.1
INTERACTION WITH COMPUTERS USING INPUT DEVICES
Input Device is a device by which input is fed into a computer’s central processor.
3.1.1 KEYBOARD
This is the most common computer input device. All keyboards are used to enter data and
text information into a computer, but computer keyboards differ in four ways:
–
Characters: both alphabetic and symbolic keyboards are available depending on the
country to be put into use.
–
Key Arrangement: the arrangement of the keyboard’s keys varies. The QWERTY
keyboard is the most common in English speaking countries. This keyboard uses the
conventional typewriter layout, in which the top row of alphabetic keys begins with
the letters Q, W, E, R, T, and Y (reading from left to right).
–
Special-Purpose Keys: certain keys are designed to assist the user to enter data or
information.
• Numeric Keys: these are found to the right of the alphabetic keys section on a
keyboard, used to key in numeric characters.
50
• Function Key: A key designed to assist the computer’s user to control
processing, e.g. the F1 key used in most software to invoke the help file that
guides user through the use of the application.
–
Detachability: most desktop computers have keyboards that can be detached from the
rest of the computer system. The most popular of this kind are the wireless keyboards
that transmit data to the computer electronically.
Figure 4.1
An example of a computer Keyboard
Source: (O’Leary, 2004).
3.1.2 TERMINAL
A terminal is a combination of keyboard and video screen that accepts input and displays it
on the screen.
–
Dumb Terminals
–
Automated Teller Machines (ATMs)
–
Point-of-sale (POS) Terminals
51
Figure 4.2
A Dumb Terminal.
Source: (Google Images, 2009).
3.1.3 SCANNERS
–
Source Data Automation: A method of data entry in which details enter computers
directly from their written or printed forms without the intermediate step of keying.
Scanning: The process of transforming written or printed data or information into a
digital form that is entered directly into the computer.
Figure 4.3
An example of a Flat-Bed Scanner.
Source: (Google Images, 2009).
52
3.1.4 OPTICAL CHARACTER RECOGNITION (OCR)
OCR is a technology by which devices read information on paper and convert it into
computer-processible form. The following are different forms of OCR:–
Optical Mark Reader: An OCR device that recognises the location of dark marks on a
special form as the form is scanned.
–
Optical Character Reader: An OCR device that recognizes printed information rather
than just dark marks.
–
Magnetic Ink Character Recognition: A form of optical character reading in which
pre-printed information written in magnetic ink is read optically or sensed
magnetically.
–
Optical Code Reader: An OCR device used to read bar codes.
–
Universal Produce Code (UPC): A bar code that identifies a product by a series of
vertical lines of varying widths representing a unique product number.
–
Image Scanning: Examining an image and translating lines, dots, and marks into
digital form.
–
Flatbed Scanner: A large image scanner that works like an office photocopier.
–
Resolution: The clarity of sharpness of an image.
3.1.5 DIGITISERS
Digitiser is an input device that translates measured distances into digital values that the
computer can process.
Figure 4.4
Lenovo Digitiser.
Source: (Google Images, 2009).
53
3.1.6 POINTING DEVICES
They accept pointing gestures and convert them into machine readable input
– Mouse: An input device with a small ball underneath that rotates, causing a
corresponding movement of a pointer on a display screen.
Figure 4.5
A Computer Mice
Source: (O’Leary, 2004).
– Touchpad: An alternative to the mouse that senses the user’s finger movement
and downward pressure, moving the cursor in the corresponding direction on
the display screen.
Figure 4.6
An example of a computer touchpad.
Source: (Google Images, 2009).
54
– Pointing Stick: A device that positions the cursor on the computer screen.
Figure 4.7
A Laptop Pointing Stick.
Source: (Google Images, 2009).
– Light Pen: An input device that uses a light-sensitive cell to draw images and
to select options from a menu of choices displayed on a computer screen.
Figure 4.8
A Computer light pen.
Source: (Google Images, 2009).
55
– Joystick: An input device used to control the actions in computer games or
simulations. The joystick extends vertically from a control box.
Figure 4.9
A black hawk Joystick.
Source: (Google Images, 2009).
– Trackball: An input device that consists of a ball mounted on rollers. As the
user rotates the ball in any direction, the computer senses the movement and
moves the cursor in the corresponding direction.
Figure 4.10 A Trackball.
Source: (Google Images, 2009).
56
– Stylus: A pen like instrument that is used to trace images on paper for
translation into electronic form.
Figure 4.11 A Stylus.
Source: (Google Images, 2009).
3.1.7 DIGITISING TABLE
This is a device by which an image on paper can be translated into electronic form.
Figure 4.12 A Digitising Table.
Source: (Google Images, 2009).
57
3.1.8 DIGITAL CAMERA
A digital camera captures a photographic image as a collection of tightly grouped dots that
can be stored on disk or in memory.
Figure 4.13 Olympus 7.1 Mega Pix Digital Camera.
Source: (Google Images, 2009).
3.1.9 DIGITAL VIDEO CAMCORDERS
It is used to capture the sound and sight of events on videotape, information is recorded as
individual bytes of information. Digital recording thus increases the quality of both audio and
video.
Figure 4.14 Digital Video Camcorders
Source: (Google Images, 2009).
.
58
3.1.10 VOICE AND SOUND INPUT DEVICES
This is an input device that can be attached to a computer to capture the spoken word in
digital form. Used as an assistive device for the disabled.
Figure 4.15 Capturing and Digitising Sounds
Source: (Senn, 2004).
3.1.11 BAR CODE
A bar code is a computer-readable code consisting of bars or lines of varying widths or
lengths.
Figure 4.16 Bar code and Bar code Scanner.
Source: (Google Images, 2009).
59
3.1.12 WAND
A wand is an input device used to read a bar code and input this information directly into a
PC.
Figure 4.17 Wand Devices.
Source: (Google Images, 2009).
3.1.13 MULTIMEDIA
This is a system that contains standard PC features but also has the capability to handle audio,
video, animation, and graphics.
Figure 4.18 A Multimedia Device.
Source: (Google Images, 2009).
60
3.2
THE PURPOSE OF THE MOUSE
The mouse is used to point at the screen (monitor), the process is called pointing. Everything
you do with a mouse is accomplished by combining pointing with other techniques, such as:
– clicking,
– double clicking
– dragging
– right clicking
– scrolling
4.0
CONCLUSION
Input Devices are devices which enable data, information and instructions to be transmitted
into the Computer system. They act as a gateway for receiving input usually in user
understandable form from the outside world and convert it to machine understandable form
which the Computer can understand.
5.0
SUMMARY
In summary you have learnt about:
• The special keys on the keyboard
• Purpose of the mouse
• Other input devices, such as: scanning devices, image capturing devices, digitizing
devices, audio input devices and assistive input devices.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. List three pointing devices
b. Which category of device is the Optical Character Recognition (OCR)?
c. What are the basic functions of a mouse?
d. What category of device is the joystick and what is it used for?
7.0
FURTHER READING/REFERENCES
•
•
•
•
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
61
MODULE 1
UNIT 5:
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
OUTPUT DEVICES
1.0
Introduction..................................................................................................................51
2.0
Objectives.....................................................................................................................51
3.0
Main Content................................................................................................................51
3.1
Output and Information Distribution Devices.............................................51
3.2
Types of Output Devices..............................................................................51
3.2.1 Visual Displays (Monitors) .............................................................52
3.2.2 Data Projector..................................................................................53
3.2.3 Printers.............................................................................................54
3.2.4 Audio Response Unit.......................................................................55
3.2.5 Television........................................................................................56
3.2.6 Plotter..............................................................................................56
3.2.7 Film Recorder.................................................................................57
4.0
Conclusion....................................................................................................................58
5.0
Summary......................................................................................................................58
6.0
Tutor Marked Assignment...........................................................................................58
7.0
Further Readings/References.......................................................................................58
62
1.0
INTRODUCTION
In Unit 4, you read about the input devices, its uses, types and technologies. This unit will
introduce you to the output devices and their uses in business.
2.0
OBJECTIVES
At the end of this unit, you should be able to:
•
Define an Output device.
•
Identify the types of output devices and their properties.
•
State their various functions and uses in business.
3.0
MAIN CONTENT
An output is the results of inputting and processing data and information returned by the
computer, either directly to the person using the system or to secondary storage.
3.1
OUTPUT AND INFORMATION DISTRIBUTION DEVICES
Output devices are devices through which computer transmits information to the outside
world. Output devices work to transform information processed in the computer, which is in
machine form, to human understandable forms e.g. text, pictures etc. With the aid of output
devices information can be viewed, heard, and printed.
3.2
TYPES OF OUTPUT DEVICES
Example of output devices are:
•
Visual Displays (Monitors)
•
Data Projector
•
Printers
•
Audio Response Unit
•
Television
•
Plotter
•
Film Recorder
63
3.2.1 VISUAL DISPLAYS (MONITORS)
A computer’s visual display. It is a computer hardware that resembles a television. It is
capable of displaying text and graphics. A monitor is one type of computer display, defined
by its CRT screen. Other types of displays include flat, laptop computer screens that often use
liquid-crystal displays (LCDs). Other thin, flat-screen monitors that do not employ CRTs are
currently being developed. Visual displays can be distinguished using the following features;
– Size
•
–
Colour
•
RGB Display: A video screen display with the ability to create 256 colours and
several thousand variations on these colours by blending shades of red, green, and
blue.
•
Monochrome Display: A video screen display that shows information using a single
foreground colour on a contrasting background colour (e.g. black on white).
–
Resolution
•
–
Pixels: The dots used to create an image; the higher the number of dots, the better the
resolution of the image.
Bit Mapping: A feature of some monitors that allows each dot on the monitor to be
addressed or controlled individually. Graphics created through bit mapping are sharp
and crisp.
•
–
Character Addressing: The precursor to bit mapping that allowed only full characters
to be sent to and displayed on a VDT.
Graphics Standard
•
–
Monitors come in various sizes, ranging from the small screen built into palmtops and
laptops to the extra-large monitors used for special purpose by engineers and
illustrators who need to examine fine details closely
Graphic Adapter Card: An interface board between a computer and monitor that is
used to determine the monitor’s resolution and use of colour.
Multisync/Multiscan Monitors: Monitors designed to work with a variety of graphics
standards.
64
Figure 5.1
A CRT and LCD Flat Screen Monitor.
Source: (Google Images, 2009).
3.2.2 DATA PROJECTOR
Data Projector: Equipment connected to the computer’s display output port by a data cable
that is used to show the contents of a computer video display on a movie screen.
–
Liquid Crystal Display (LCD) projector: An LCD projector works on the principle of
blocking light rather than emitting it. The brightness of the light (measured in lumens)
determines how easily the images can be viewed in a room with ordinary lighting (as
opposed to a darkened room).
–
Digital Light Processing (DLP) Projector: This projector builds images on screen by
digitally controlling the reflected angle of incident light, converging it with a prism,
and passing the image through a lens on to the screen. It has clear, sharp images and
high contrast text as well as rich colour in projected images.
Figure 5.2
Projectors.
Source: (Google Images, 2009).
65
3.2.3 PRINTERS
–
Hard Copy: The paper output from a printer.
–
Nonimpact Printing: A printing process in which no physical contact occurs between
the paper and the print device; the characters are produced on the paper through a
heat, chemical, or spraying process.
–
•
Laser Printer: A nonimpact printer that uses laser beams to print an entire page
at once.
•
Ink-jet Printer: A printer that sprays tiny steams of ink from holes in the print
mechanism onto the paper in a dot pattern that represents the character or image
to be printed.
•
Thermal Printer: A printer that heats a wax-based coloured ink contained in the
printer ribbon and transfers it to a special paper.
Impact Printing: A printing process in which the paper and the character being
printed come into contact with each other.
•
Line Printer: Prints a full line at one time on continuous-form paper. Because of
their high speed, which ranges up to several thousand lines per minute, line
printers have been used in computer centres that routinely print large volumes of
documents or very long reports.
•
Dot Matrix Printing: Characters and images are formed by wire rods pushed
against a ribbon and paper to create characters that are actually a collection of
small dots.
•
Characters Printer: A printer that prints one character at a time. Its speed is
rated according to the number of characters printed per second.
Figure 5.3.1 Ink-jet Printing Process
Source: (Senn, 2004).
66
Figure 5.3.2 A LaserJet Printer.
Source: (Google Images, 2009).
3.2.4 AUDIO RESPONSE UNIT
Audio Response Unit/Speech Synthesizer: An output device that transforms data or
information into sound.
–
Speakers: - Speakers are connected to computers through Sound cards, so as to listen
to voice outputs.
Figure 5.4
A set of mini Computer speakers.
Source: (Google Images, 2009).
67
3.2.5 TELEVISION
Television, system of sending and receiving pictures and sound by means of electronic
signals transmitted through wires and optical fibres or by electromagnetic radiation.
Television has a variety of applications in society, business, and science. The most common
use of television is as a source of information and entertainment for viewers in their homes.
Security personnel also use televisions to monitor buildings, manufacturing plants, and
numerous public facilities. Public utility employees use television to monitor the condition of
an underground sewer line, using a camera attached to a robot arm or remote-control vehicle.
Doctors can probe the interior of a human body with a microscopic television camera without
having to conduct major surgery on the patient
Figure 5.5
CRT and LCD TV Sets.
Source: (Google Images, 2009).
3.2.6 PLOTTER
Plotter: An output device that draws image information (such as charts, graphs, and
blueprints) stroke by stroke. Computer device for drawing graphs: a computer output device
that draws graphs and other pictorial images on paper, sometimes using attached pens.
Large plotters are used in computer-aided design applications to produce more rapidly the
engineering drawings and architectural plans once prepared by skilled drafts people
68
Figure 5.6
A Plotter.
Source: (Google Images, 2009).
3.2.7 FILM RECORDER
Film Recorder: A Film Recorder is a graphical output device for transforming digital images
on a computer screen into a photographic film.
Figure 5.7
A Film Recorder.
Source: (Google Images, 2009).
69
4.0
CONCLUSION
Output Device is a device that makes the results of processing available outside of the
computer to be used in business decision making. It brings out the information after the data
has been processed.
5.0
SUMMARY
In summary you have learnt that the input and output devices:
•
Play a great role in enhancing business decision taking, through outputting of
information.
•
Are of different types and technology.
•
Transform data in machine form, to human understandable forms e.g. text and
pictures.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. Briefly define an output device.
b. Discuss the use of a data project and list its types.
c. What does RGB stands for in a monitor?
d. Define the following: film recorder, speaker and laser printer.
7.0
FURTHER READING/REFERENCES
•
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
•
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
70
MODULE 1
UNIT 6:
INTRODUCTION TO INFORMATION COMMUNICATION
TECHNOLOGY
STORAGE DEVICES AND MEMORY
1.0
Introduction..................................................................................................................60
2.0
Objectives.....................................................................................................................60
3.0
Main Content ...............................................................................................................60
3.1
Storage .............................................................................................................60
3.1.1 Characteristics......................................................................................60
3.2
Types of Storage...............................................................................................61
3.3
Storage Technologies.......................................................................................61
3.4
Other Magnetic Disk Storage Systems............................................................65
3.5
Memory............................................................................................................66
3.6
The Differences between Storage And Memory.............................................69
4.0
Conclusion...................................................................................................................69
5.0
Summary......................................................................................................................70
6.0
Tutor Marked Assignment...........................................……………….........................70
7.0
Further Readings/References.......................................................................................70
71
1.0
INTRODUCTION
In Unit 5, you read about the output unit or devices that help the computer to deliver its work.
In this unit you will learn about a new concept that enables the inputted data and outputted
information to be archived.
2.0
OBJECTIVES
At the end of this unit, you are expected to:
•
Understand what storage is, types and technology
•
Know the types of memory and their sizes.
•
Identify the differences between storage and memory.
•
Distinguish between primary storage (also called memory) and secondary storage
(also called storage), and between RAM and ROM.
3.0
MAIN CONTENT
Storage in computer is the process of retaining information for future use. A computer can
function with only processing, input and output devices. To be really useful however, a
computer also needs a place to keep program files and related data when they are not in use.
3.1
STORAGE
The purpose of storage is to hold data.
•
3.1.1
Secondary Storage/Auxiliary Storage: A storage medium that is external to the
computer, but that can be read by the computer; a way of storing data and information
outside of the computer itself.
CHARACTERISTICS OF STORAGE
–
Reliable: storage retains its data when the power is turned off.
–
Economical: storage is cheaper than memory.
–
Compact: large volumes of data can be stored at high density.
–
Convenient: storage is easy to use and can transfer data rapidly, though not as fast as
memory.
72
3.2
TYPES OF STORAGE
•
By Read/Write Capability
– Read/Write: A computer application can use storage for both writing and
reading data.
•
By Access Capability
– Sequential Storage: Elements of data are read one right after the other.
– Sequential Access: The contents are accessed in sequence.
– Random Access Storage: The process of retrieving a particular record of
information from any track directly.
– Random Access Device: The self-contained unit that holds and processes the
disk.
3.3
STORAGE TECHNOLOGIES
•
Magnetic Storage
– Magnetic Tape: A magnetic storage medium in which data are stored on large
reels of tape.
– Read/Write Head: A device that records data by magnetically aligning
metallic particles on the medium. The write head records data and the read
head retrieves them.
– Disk Cartridge: The cartridge, a hard disk sealed in a protective package, is
inserted into the disk drive for reading and writing data.
•
Extended Disk Storage Alternatives
– Redundant Arrays of Independent Disks (RAID): A set of small disk drives
that work together as a single unit.
•
Striping: A method of combining multiple physical drives into one
logical storage unit.
•
Fault Tolerance: The capability for a computer application to continue
processing even if a disk drive fails.
•
Disk Mirroring: The most frequently used form of RAID; it uses pairs
of drives within the array and duplicates the entire contents of a disk
on a second disk.
73
•
Optical Storage
– Optical Storage Device: A device that uses a beam of light produced by a
laser to read and write data and information.
Figure 6.1
A WORM Opt ical disc.
Source: (Google Images, 2009).
•
Flexible Disks
– Flexible Disk/Diskette/Floppy Disk: A type of magnetic disk made of flexible
plastic.
Figure 6.2
A 3 ½ and 5½ diameter floppy discs.
Source: (Google Images, 2009).
74
•
Hard Disk
A type of secondary storage that uses nonflexible, non removable magnetic disks
mounted inside the computer to store data or information.
– Hard Drive/Disk Drive: The device that holds and processes the disk.
– Record: A grouping of data items that consists of a set of data or information
that describes an entity’s specific occurrence.
Disk Storage Areas
– Track: The area in which data and information are stored on magnetic tape or
disk.
– Sector: A subdivision of a track on a magnetic disk; used to improve access to
data or information.
– Cylinder: A storage concept that refers to the same track location on each of
the platters.
– Head Crash: The situation that occurs when the read/write heads that
normally float close to a magnetic disk’s surface actually touch the surface.
– Disk Pack: A stack of disks, enclosed in a protective plastic cover that can be
lifted onto or off a disk drive.
– Random Access Storage/Direct Access Storage: The process of retrieving a
particular record of information from any track directly.
Figure 6.3
A Seagate Hard disc
Source: (Google Images, 2009).
75
•
Disk Controller Interfaces
– Hard Disk Controller: A hardware interface that may be built into the hard
drive itself, in the form of an expansion board, or a connection on the system
board.
– Integrated Drive Electronics (IDE): A standard electronic interface used
between the bus or data path on a computer system board and the computer’s
disk storage devices.
– Small Computer System Interface (SCSI): A device created to speed the
transfer of data between hard disks and other peripherals.
– Universal Service Bus (USB): A recent addition to PCs that can connect up to
128 devices, ranging from computer disk storage to a variety of multimedia
devices.
– Fire Wire: One of the fastest peripheral interface standards ever developed.
– Disk Cache: Disk caching allows the system to store information that is
frequently read from a disk in RAM.
STORAGE AREA NETWORK
SAN is a high-speed network or system that allows different kinds of storage devices, such as
tape drives and disk arrays, to be shared by all users through network servers.
Figure 6.4
Storage Area Network
Source: (Senn, 2004).
76
3.4
OTHER MAGNETIC DISK STORAGE SYSTEMS
•
USB Drives: Consisting of flash memory and a USB connection, it can read and write
data when connected to the computer’s USB port.
•
Zip Drive: A removable storage device that uses hard-shelled removable Zip disks,
which can store up to 750 MB of information.
•
SuperDisk: A storage alternative developed by Imation (originally part of 3M Corp.)
that has a capability of 120 MB.
MAGNETIC TAPE
•
Tape for Large Systems and SANs.
•
Tape for PCs.
– Digital Audiotape (DAT): A 4-mm tape that uses a different recording system
(called helical scanning), similar to that found on videotape recorders.
– Advanced Intelligent Tape (AIT): Latest tape alternative that was introduced
in the late 1990s for use with PCs functioning as servers and with midrange
systems.
Figure 6.5
A cassette magnetic tape.
Source: (Google Images, 2009).
OPTICAL STORAGE
•
CD-ROM Disk: Short for “compact disk-read only memory,” an optical storage
medium that permits storage of large amounts of information. CD-ROM disks can
only be written to and cannot be erased.
77
– Standard CD
– Mini-CD
– Business Card CD/Personal Compact CD (PCD): A variant on the miniCD, it holds 20 to 60 MB, depending on the physical size of the CD.
•
CD-ROMs have two formats
– CD-R disks: A disk that allows users to write information to a disk only once
but to read it many times (sometimes known as worm optical storage).
– CD-RW disks: A disk that combines the eraseability and editing options of
magnetic storage devices with the permanence, capacity, and reliability of
optical storage.
– CD Recorder: Also known as a CD writer or CD burner, this equipment is
attached to a PC to create CDs.
•
Digital Video Disk (DVD): The newest generation of optical storage. It appears to
operate the same way and has the same dimensions as a CD-ROM but has a much
larger capacity.
– DVD-RAM: A rewritable DVD form that can be used in PCs.
3.5
MEMORY
•
Primary Storage/Primary Memory/Main Memory/Internal Memory: Storage within
the computer itself. Primary memory holds data only temporarily, as the computer
executes instructions.
Figure 6.6
Primary Memory Allocation
Source: (Senn, 2004).
78
PRIMARY (MAIN) MEMORY
Primary or main memory is always connected to the processor. In a computer it is usually in
the same box as the processor. When you type instructions on the keyboard of your computer,
they are put into the main memory. There are two parts of the main memory:
–
Read Only Memory (ROM) and
–
Random Access Memory (RAM).
MEMORY (RAM AND ROM)
•
Random-access Memory (RAM): Memory that permits data or information to be
written into or read from memory only as long as the computer is turned on. Other
forms of RAM include SRAM (Static RAM), DRAM (Dynamic RAM), SDRAM
(Synchronous Dynamic RAM) & DDR2. It is the memory used to store instructions
and data needed by the Central Processing unit (CPU).
•
Read-only Memory (ROM): A type of storage that offers random access to memory
and can hold data and information after the electric current to the computer has been
turned off.
MEMORY SIZE
•
Byte: A storage location in memory; the amount of memory required to store one
digit, letter, or character.
•
Kilobyte/K-byte/KB/K: One thousand bytes.
•
Megabyte/M-byte/MB/Meg: One million bytes.
•
Gigabyte/G-byte/GB/Gig: One billion bytes.
•
Terabyte/T-byte/TB: One trillion bytes.
•
Address: An identifiable location in memory where data are kept.
79
FLASH MEMORY
•
Flash Memory: Memory that retains it contents even when electricity is turned off.
Figure 6.7
A USB Flash disc.
Source: (Google Images, 2009).
Figure 6.8
Types of Memory Chips
Source: (Senn, 2004).
MEMORY (PCMCIA CARD MEMORY)
PCMCIA Card/PC card: A card designed to expand a computer’s memory.
80
Figure 6.7
A USB Flash disc.
Source: (Google Images, 2009).
MEMORY (BOOTING)
•
Boot: To turn on the computer system and let the built-in self-test run.
•
Cold Boot: The system is turned on and started from an off state. The CPU invokes
the ROM BIOS boot program, which in turn, runs the power-up, self-tests and loads
the operating system from disk storage.
•
Warm Boot: In a restart, the BIOS know the system is already running, data is written
in a specific memory location checked by the BIOS and skips the power-on test.
MEMORY CHIPS
Single In-line Memory Module (SIMM): A multiple-chip memory card inserted as a unit
into a predesignated slot on a computer’s system board.
•
Installed Memory: The amount of memory included by a computer’s manufacturer on
its memory board.
•
Maximum Memory: The most memory that a processor can hold.
3.6
THE DIFFERENCES BETWEEN STORAGE AND MEMORY
Although the functions of storage and memory are similar, they work in different ways.
•
There is more room in storage than in memory, just as there is more space in a file
cabinet than on a table top.
•
Contents are retained in storage when the computer is turned of, whereas the program
or data you put into memory disappear when you shut down the computer
•
Storage is very slow compared to memory, but it is much cheaper than memory.
81
4.0
CONCLUSION
Storage and memory look similar but perform different tasks. Memory is used to load
program files and is volatile, while storage are used to hold data permanently and to be
retrieved for future use.
5.0
SUMMARY
In this unit, we learnt that the:
•
The functions of storage and memory are similar, they work in different ways.
•
The memory - serves the purpose of temporary storage (holding data and instruction)
and also used to boot the computer system.
•
Storage come in different types, sizes, and are made of various technologies.
•
Storage can be used on a local area network- allowing different kinds of storage
devices, such as tape drives and disk arrays, to be shared by all users through network
servers.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What does SAN stands for in storage?
b. What are the other magnetic disk storage systems?
c. Is memory and storage the same? Explain.
d. What does the following means in memory?
–
–
–
–
–
–
7.0
Byte
Kilobyte/K-byte/KB/K.
Megabyte/M-byte/MB/Meg
Gigabyte/G-byte/GB/Gig
Terabyte/T-byte/TB
Address
FURTHER READING/REFERENCES
•
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
82
MODULE 2
UNIT 7
DATABASES AND COMPUTER NETWORKS
DATABASES
1.0
Introduction..................................................................................................................72
2.0
Objectives....................................................................................................................72
3.0
Main Content ………..................................................................................................72
3.1
What Is A Database?......................................................................................72
3.2
Reasons for Using Database..........................................................................74
3.3
Types of Databases........................................................................................75
3.3.1 Flat Databases...........................................……………….................75
3.3.2 Relational Databases.........................................................................77
3.4
Types of Relation in a Relational Database..................................................78
3.5
Developing Database Application................................................................79
3.6
Database Normalisation................................................................................81
4.0
Conclusion...................................................................................................................83
5.0
Summary......................................................................................................................83
6.0
Tutor Marked Assignment............................................................................................83
7.0
Further Readings/References...........................................……………........................83
83
1.0
INTRODUCTION
In module 1, you were introduced to how data is being processed into information using the
basic ICT tools (computer’s hardware and software). In this unit you will be introduced to a
new concept of how you can collect related information and store the Information in a
structured format.
2.0
OBJECTIVES
By the end of this unit you should be able to:
•
Describe the main components of a database.
•
Describe the types of databases.
•
Identify when a business should use a spreadsheet and when it should use a database.
•
Identify the seven-step sequence for developing database applications.
3.0
MAIN CONTENT
A database is a single organized collection of structured data, stored with minimum
duplication of data items so as to provide a consistent controlled pool of data. It is a good
program to use to manage list that are entirely numbers, such as addresses and phone
numbers, inventories and membership rosters.
3.1
WHAT IS A DATABASE?
A database is a collection of data and information describing items of interest to an
organization.
With a database you could sort the data by name or city or postal code or by any individual
item of information recorded. You can create forms to enter or update or just display the data.
You can create reports that show just the data you are interested in, like members who owe
dues.
Some basic components of a database are:
•
Entities and Attributes
– Entity: A person, place, thing, event, or condition about which data and
information are collected.
– Attribute: A category of data or information that describes an entity. Each
attribute is a fact about the entity.
84
•
Data Items and Records
– Data Item: A specific detail of an individual entity that is stored in a database.
•
Data Items and Records
– Record: In a database, a designated field used to distinguish one record from
another.
– Relational Database: A database in which the data are structured in a table
format consisting of rows and columns.
– Relation/File: The table in a database that describes an entity.
– Tuples: The rows of a relation. Also called records.
– Fields: The column of a relation. Also called attributes.
Figure 7.1a The Elements of a Relation
Source: (Senn, 2004).
85
Figure 7.1b Entity Description in a Database
Source: (Senn, 2004).
3.2
REASONS FOR USING DATABASE
The following are reasons for using a database:
•
Enterprise Database: Large multiuser database systems developed and maintained by
IT professionals.
•
Personal Database (PC Database): Typically reside on personal computers and are
designed to support a particular function.
• Storing Data
• Retrieving Data
– Query/Querying: A question to be answered by accessing the data in a
database.
• Editing: Adding, deleting, or changing the data about companies.
• Organizing Data
• Distributing Data and Information
86
3.3
TYPES OF DATABASES
Both spreadsheets and databases can be used to handle the same information, but each is
optimized to handle a different type of data most efficiently. The larger the number of
records, the more important the differences are. Some popular databases include MS Access,
dBase, FoxPro, Paradox, Approach, MySQL, and Oracle.
3.3.1 FLAT DATABASES
A database that consists of a single table. Lightweight database programs such as the
database component in Microsoft Works are sometimes called 'flat-file managers' (or list
managers) because they can only handle single-table databases. More powerful programs,
such as FileMaker Pro, Access, Approach and Paradox, can handle multi-table databases, and
are called relational databases managers, or RDBMSs.
A flat database contains files which contain records which contain fields. The earliest and
simplest databases are flat databases, they are easy to setup and understand. It may require
entering the same information in many records. Examples are text databases and spreadsheets
Figure 7.2
A flat database, files, records, and fields.
Sources: (O’Leary, 2004).
87
•
A text databases
This is a plane text file where the fields are separated by a particular character like a vertical
bar “|” or a comma “,” or a semi-colon “;”. The example bellow put the vertical bar between
each field. The first record shows the names of the fields.
A text database is hard to read in this raw form. A database program can show each record
separately in a more readable display. It is hard to create a report that contains just the parts
you want to see.
Figure 7.3
A Text database
Sources: (Smith, 2009).
•
A Spreadsheet
A spreadsheet can work as a flat database. Each field is in a separate column and each row is
a single record. The example bellow shows how quickly a record gets wider than the screen.
You cannot use two rows for one record.
88
Figure 7.4
A Spreadsheet
Sources: (Smith, 2009).
3.3.2 RELATIONAL DATABASES
A relational database contains tables which are linked together. Each table contains records
which contain fields. Microsoft Access, Oracle and other relational databases are more
advanced and more efficient. This kind of database uses a set of tables which are linked
together. Using a well-designed relational database can greatly reduce the amount of data you
must enter each time you add a record. For large number of records, a relational database can
search through the records faster.
Relational database can be complex to set up, using many tables, but it reduces the
duplication in data entry, records are searched faster, forms are created and reports that
display only the data you want to see. Queries can be created to answer questions that are
hard or impossible to answer in flat databases.
Bellow is an illustration of the tables in a small database that records information about
insurance agents and policy holders. The particular insurance office works with several
different insurance companies. There are seven tables in the database. The lines show which
fields in each table are the same. These link the tables together.
89
Figure 7.5
Relational Database
Sources: (Smith, 2009).
Each agent can be licensed with several different companies and in several different states. In
a flat database you would have to have a record for each agent for every company and state
he is licensed with, repeating the agent info for each record. This is too much typing.
You can design a form so that you can do this all in one spot. This is easier than repeating so
much information for each record as you would do in a flat database. The images below show
the two screens for the agents info form. This form can be used for entering new agents as
well as for displaying the current ones.
90
3.4
TYPES OF RELATION IN A RELATIONAL DATABASE
A relation specifies the association between two or more entities for example Town and
Person. The relation should specify the semantic of the association like: A person lives in a
town.
A relation is symbolized by an oval with its semantic inside the oval. A relation is further
specified by cardinalities that indicate the number of associated instances. For example;
•
A person lives in a minimum of one town and in a maximum of 1 town
•
A town is inhabited by a minimum of one person and a maximum of n (indicating
several)
Figure 7.6
Entity Relationship Diagram.
Source: (DAVID, 2008).
Relationships
Relationship is the association between entities, it could be represented graphically using an
entity relationship data model. Relationships between real-world entities can be quite
complex, involving numerous entities each having multiple relationships with each other. For
example, a family has multiple relationships between multiple people—all at the same time.
In a relational database such as Microsoft Access, however, you consider only relationships
between pairs of tables. These tables can be related in one of three different ways: one-toone, one-to-many or many-to-many.
91
3.5
DEVELOPING DATABASE APPLICATION
Database Application is a computerized database routine for collecting, retrieving, or
manipulating data to meet recurring needs. There are seven step sequence:
•
Study the Problem: Describe the system’s data entry (input) requirements, inquiry
requirements, and output requirements.
•
Determine the Requirements: Determine the problem’s characteristics and how
database creating and processing can assist in solving the problems.
•
Design the Database: Identify entities of interest, determine the data or information
that describes them, and determine which data items will be used to distinguish one
entity from another.
– Index Key/Search Key: A data item used by database management software to
locate a specific record.
•
Create the Database: Name the database; establish the database structure (field
names, types, widths, and decimal positions; field indexation).
– Indexing: A database system’s capability to find fields and records in the
database.
•
Design the Application: Develop data entry, report generation, and query-processing
methods.
– Data Entry: The process of populating a database with data and information.
•
Data Entry Form: Custom-developed video display used to enter and
change data in a database.
– Report Generation
– Query Processing
•
•
Relational Operator: A symbol that tells a database system to make a
comparison to call up the requested data.
Create the Application: Write the programs to perform data-processing tasks.
– Custom Programming: In a database system, the writing of detailed
procedures, using the commands and functions built into the database
management software.
– Application Generation: In a database system, the use of menus and simple
commands to describe the application to a system program that creates the set
of detailed commands.
•
Test the Application: Evaluate the application’s processes and procedures to ensure
they are performing as expected.
92
Table 7.1 Field Types
FIELD TYPE
DESCRIPTION
EXAMPLE
Character or
Alphanumeric
Alphabetic or special characters and numbers (can not Kk9, 2ND
be used in arithmetic processes)
Avenue, Na’omi
Numeric
Any integer or any number with a decimal point or 540, -12, 4.7
minus sign (can be used in arithmetic processes)
Floating Point
Decimal numbers (typically used in applications 128.6
involving frequent multiplication and division)
Logical
One space used to indicate True or False, or Yes or No
Memo
Text data used to explain or annotate other details “Details captured
contained in the record, frequently at length.
by Binta
Abraham During
interview with
Students at
NOUN on 10
August”
Date
Calender date in the format mm/dd/yyyy (Month, Date, 22/15/2009
Year)
Tt, Ff, Yy, Nn
Source: (Senn, 2004).
3.6
DATABASE NORMALISATION
The process of structuring data to minimize duplication and inconsistencies. The process
usually involves breaking down a single table into two or more tables and defining
relationships between those tables. Normalisation is usually done in stages. The first three
levels in normalising a database are:
• First Normal Form (1NF): There should be no repeating groups in a table. For example,
say you have a students table with the following structure:
Student Table (Student_ID, name, date of birth, advisor, advisor's telephone, student,
course ID 1, course description 1, course instructor 1, course ID 2, course description
2,course instructor 2)
The repeating course fields are in conflict with first normal form. To fix the problems created
by such repeating fields, you should place the course information in a separate course table,
and then provide a linking field (most likely Student_ID) between the students table and the
course table.
93
•
Second Normal Form (2NF): No non-key fields may depend on a portion of the primary
key.
For example, say you create a course table with the structure:
Student_ID, course ID, course description, course instructor
You can create a unique primary key by combining Student_ID + course ID (Student_ID is
not unique in itself, as one student may take multiple courses; similarly, course ID is not
unique in itself as many students may take the same course; however, each student will only
be taking a particular course once at any one time, so the combination of Student_ID + course
ID gives us a unique primary key).
Now, in 2NF, no non-key fields (course description, course instructor) may depend on a
portion of the primary key. That, however, is exactly what we have here: the course instructor
and course description are the same for any course, regardless of the student taking the
course.
To fix this and put the database in second normal form, you create a third table, so our
database structure now looks like this (with key fields in italics):
Student table (Student_ID, name, date of birth, advisor, advisor's telephone)
Student courses table (Student_ID, course ID)
Courses table (course ID, course description, course instructor)
•
Third Normal From (3FN): No fields may depend on other non-key fields. In other
words, each field in a record should contain information about the entity that is defined by
the primary key.
In our students table, for example, each field should provide information about the particular
student referred to by the key field, Student_ID. That certainly applies to the student's name
and date of birth. But the advisor's name and telephone doesn't change depending on the
student. So, to put this database in third normal form, we need to place the advisor's
information in a separate table:
Student table (Student_ID, name, date of birth, advisor ID)
Student courses table (Student_ID, course ID)
Courses table (course ID, course description, course instructor)
Advisor table (advisor ID, advisor name, advisor telephone)
94
4.0
CONCLUSION
When you are storing data, caution need to be taken, especially in the database design stage
to avoid duplicates of data. PC database are for limited access and small size database, while
enterprise database are for distributed environment.
5.0
SUMMARY
In this unit, you learnt that:
•
the process of structuring data to minimise duplication and inconsistencies by
breaking down a single table into two or more tables and defining relationships
between those tables is known as normalization.
•
data can be either stored on a single PC or over a distributed network
•
there are procedures followed to develop a database application.
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What is a database?
b. List two reasons for using database.
c. What is Database Normalisation?
d. What are the steps taken to design a Database Application?
7.0
FURTHER READING/REFERENCES
•
DAVID, A. (2008). Data Modeling. Retrieved November 15, 2008 from,
http://ui-n2. loria.fr
•
Elmasri, R., Navathe, S. B. (2004). Fundamentals of Database Systems (4th Edition).
Essex, UK: Pearson Higher Education.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 2009, from
http://www.jegsworks.com.
95
MODULE 2
UNIT 8:
DATABASES AND COMPUTER NETWORKS
DATABASE MANAGEMENT SYSTEM (DBMS).
1.0
Introduction..................................................................................................................85
2.0
Objectives…........................................….....................................................................85
3.0
Main Content ………………………….......................................................................85
3.1
Database Management System (DBMS)……..................................................85
3.2
Objectives of Database Management Systems.................................................86
3.3
Classification of DBMS...................................................................................87
3.4
Special Purpose Databases...............................................................................87
3.5
DBMS Structure...............................................................................................88
3.6
Database Administrator (DBA) .......................................................................89
4.0
Conclusion…........................................…....................................................................89
5.0
Summary…........................................…......................................................................89
6.0
Tutor Marked Assignment...........................................................................................90
7.0
Further Readings/References…........................................….......................................90
96
1.0
INTRODUCTION
In Unit 7, you were introduced to the concept of Information Repository (database). In this
unit you will be introduced to manage in a database using specific software known as the
database management system (DBMS).
2.0
OBJECTIVES
By the end of this unit you should be able to:
3.0
•
Know what a database management system (DBMS)is
•
List and describe five objectives of database management systems.
•
Identify criteria used in classifying a DBMS
•
The different data models of a DBMS.
MAIN CONTENT
Database management system is a program which lets you manage information in databases.
Lotus Approach, Microsoft Access and FileMaker Pro, for example, are all DBMSs, although
the term is often shortened to 'database'. So, the same term is used to apply to the program
you use to organise your data and the actual data structure you create with that program. The
database management system is complex software systems that constructs, expand and
maintains the database. It also controls the interface between the user and the data in the
database.
3.1
DATABASE MANAGEMENT SYSTEM (DBMS)
The DBMS maintains the data in the database by: adding new records, deleting “Unwanted”
record, and amending records.
The DBMS also has the function of providing security for data in a database through:
protecting data against unauthorized access, safeguarding data against corruption and
providing recovery and restart facilities after a hardware or software failure.
The DBMS provides facilities for different types of file processing: process a complete file
(serially and sequentially), process required records (selective, sequential and random), and
retrieve individual records.
97
3.2
OBJECTIVES OF DATABASE MANAGEMENT SYSTEMS
The Objectives of Database Management Systems are:
•
Data Definition Language (DDL): A tool provided in a database management system
that allows users to define the database.
•
Data Manipulation Language (DML): A tool provided in a database management
system that allows users to store, retrieve, and edit data in the database.
•
Integrating Databases: database management systems allow the merger of separate
files, created at varying times or by different people. The data needed to solve a
particular problem reside in several databases, problem solvers must be able to
integrate databases. Integration is often done to process an inquiry or to create a
report.
•
Reducing Redundancy: redundancy is the duplication between databases. When files
are developed independently, some data may be repeated in the databases, and
unfortunately, these multiple copies sometimes become inconsistent.
•
Sharing Information: information can be stored in a database once and then retrieved
any number of times by any authorized user of the database.
•
Maintaining Integrity: a database that is both secure and reliable is said to have
integrity. Information can be accessed on by authorized users.
•
Enabling Database Evolution: databases are dynamic, they are constantly changing.
Databases change in two way:
Content – the data items in current record, new records are added, and existing
records are deleted.
Structure – the data items that make up a record can change the logical structure of a
database, either because fields are added or deleted, because data items’
characteristics change, or because the way the database is stored physically changes.
Table 8.1 Popular PC Database Management Systems
SOFTWARE
MANUFACTURER
VERSIONS AVAILABLE
Access
Microsoft
Windows and Macintosh
FileMaker Pro
Apple
Windows and Macintosh
Visual FoxPro
Microsoft
Windows and Macintosh
Interbase
Borland
Windows and Linux
Source: (Senn, 2004).
98
3.3
CLASSIFICATION OF DBMS
Several criteria are normally used to classify DBMSs.
•
•
The first is the data model on which the DBMS is based. The main data model used
in many current commercial DBMSs is the relational data model. The basic
relational data model represents a database as a collection of tables, where each table
can be stored as a separate file
The second criterion used to classify the DBMSs is the number of users supported
by the system.
– Single-user systems support only one user at a time and are mostly used with
personal computer (PC).
– Multi-user systems, which include the majority of DBMSs, support multiple
users concurrently.
•
A third criterion is the number of sites over which the database is distributed.
– A DBMS is centralized if the data is stored at a single computer site and can
support multiple users, but the DBMS and database themselves reside totally
at a single computer site.
– A distributed DBMS (DDBMS) can have the actual database and DBMS
software distributed over many sites, connected by a computer network.
•
3.4
A forth criterion is the cost of the DBMS. Most DBMS are expensive but there are a
few free ones like MySQL.
SPECIAL PURPOSE DATABASES
We can also classify a DBMS on the basis of the types of access path and other purpose
options for storing files.
•
General-purpose Database System: A database maintained with powerful database
management software that can be applied to just about any PC database.
•
Special-purpose Database: Predesigned for a specific use.
•
Directory: A listing of information by category.
•
Commercial and Government Topical Databases
– Economic Database: Capture details related to the state of the Nigerian
economy (other nations have comparable databases).
– Statistical Database: Include the measurement data to measure the level of
statistical activity and a means of comparing areas of activity.
99
– Financial Database: Focus on areas of monetary and investment activity,
including stock market trading, issuance of mortgages, real-estate transactions,
corporate finance, and venture-capital investment activities.
– Literary Database: Pertain to books, monographs, or reports, or to articles
appearing in newspapers and magazines. Alternatively, a literary database may
contain the actual publications themselves or links to the publications.
•
Personal Information Manager (PIM)/Contact Manager: Contains
preprogrammed features enabling users to manage data helpful in their personal
activities.
– Contacts
– Calendar
– To-Do list
–
3.5
Memos and Notes
DBMS STRUCTURE
DBMS programs are designed to work with specific data structures or data models. These
models define rules and standards for all the data in the database. Five principal data models
are:
•
Hierarchical Database: uses nodes to link and structure fields and records; entries
may be one parent node with several child nodes in a one-to-many relation ship.
•
Network Database: this is like the hierarchical except the child node may have more
than one parent in many-to-many- relationships.
•
Relational Database: data is stored in tables (relations); related tables have common
data items (key field).
•
Multidimensional Database: extend two dimensional relational tables to three or
more dimensions sometime called hyper cube.
Advantages include:
•
–
Conceptualisation – database provides an intuitive model for complex
data and relationships.
–
Processing Speed – analyzing and querying is faster.
Object Oriented: store data, instructions and unstructured data. Data organized using
objects, classes, entities, attributes, and methods.
Objects – contains both data and instructions to manipulate data.
Classes – are similar to objects grouped together
100
Entities – are a person, place, thing or event.
Attributes – similar to fields, are descriptions of entities.
Methods – describe how data is to be manipulated.
3.6
DATABASE ADMINISTRATOR (DBA)
This is a person who acts as a special manager managing the database usually a staff in the
organisation. She/he must have a sound knowledge of the structure of the database and the
DBMS. The DBA is responsible for ensuring that the data in the Database meets the
information needs of the organization and provides facilities for retrieving data and structuring
reports. To perform most of the functions the DBA will have to liase with the managers, System
Analyst (SA) and programmers who develop the system. The security and integrity of data in the
database is his/her responsibilities, and the preparation of a periodic appraisal of the data to ensure its
completeness, accuracy, and to reduce duplicates.
The DBA is also responsible for preparing manuals for the users of the system describing the
facilities the database offers and their uses and designing the data dictionary.
4.0
CONCLUSION
When you are storing data, caution need to be taken, especially in the database design stage
to avoid duplicates of data. PC database are for limited access and small size database, while
enterprise database are for distributed environment.
5.0
SUMMARY
In this unit, you learnt that:
•
the data and information can be stored using specified Software package like
Database Management System (DBMS)
•
data can be either stored on a single PC or over a distributed network
•
DBMS programs are designed to work with specific data structures or data models.
Five principal data models are:
– Hierarchical Database
– Network Database
– Relational Database
–
Multidimensional Database
–
Object Oriented
101
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What is a DBMS?
b. What are the advantages of using a Multidimensional Database?
c. Who is a DBA?
d. What is the difference between a Database and DMS?
7.0
FURTHER READING/REFERENCES
•
Elmasri, R., Navathe, S. B. (2004). Fundamentals of Database Systems (4th Edition).
Essex, UK: Pearson Higher Education.
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 15, 2009, from
http://www.jegsworks.com.
102
MODULE 2
DATABASES AND COMPUTER NETWORKS
UNIT 9:
DATABASE QUERIES
1.0
Introduction..................................................................................................................92
2.0
Objectives...........................................…………………..............................................92
3.0
Main content.................................................................................................................92
3.1
Query Language Features.................................................................................94
3.2
Structured Query Language (SQL) .................................................................94
3.2.1 Tables...................................................................................................94
3.2.2 Select Statements…..............................................................................96
3.2.3 Insert Statement…................................................................................97
3.2.4 Update Statement….............................................................................97
3.2.5 Delete Statement...................................................................................97
3.3
Other Commands Used With the SQL Statements……………………..........97
3.3.1 Join Operations.....................................................................................97
4.0
Conclusion………………………………....................................................................99
5.0
Summary………………………………......................................................................99
6.0
Tutor Marked Assignment...........................................…………………….................99
7.0
Further Readings/References.......................................................................................99
103
1.0
INTRODUCTION
In Unit 7, you learnt of a software called the database management system (DBMS) used in
managing data in a relational database. In this unit, you will discover that in recent years
there has been a major increase in the use of relational databases. An easy way of
manipulating the record at a high level was devised using the query. A query is used to filter
records from a database to show just the ones that meet certain criteria or to arrange them in a
particular order.
2.0
OBJECTIVES
By the end of this unit students are expected to;
3.0
•
define a query
•
How to construct a query to filter records
•
The most common query language (SQL)
•
The Join Operation
MAIN CONTENT
A query is a view of your data showing information from one or more tables. For instance,
using the sample database we used in the previous Unit 7 when describing normalisation, you
could query the Students database asking "Show me the first and last names of the students
who take both history and geography and have Alice Hernandez as their advisor" Such a
query displays information from the Students table (firstname, lastname), Courses table
(course description) and Advisor table (advisor name), using the keys (Student_ID, course
ID, advisor ID) to find matching information.
The query below brings together the fields from the agent info tables that are needed for
mailing labels.
104
Figure 9.1
Query Design View Window
Sources: (Smith, 2009).
The SQL code for this query looks a lot different from the design view above. No wonder a
drag-and-drop method was created.
Figure 9.2
Query Code View Window.
Sources: (Smith, 2009).
105
3.1
QUERY LANGUAGE FEATURES
A query language normally comprises a Data Descriptive Language (DDL) and a Data
Manipulative Language (DML). There are two types of queries:
•
Query By Example (QBE) and
•
Structural Query Language (SQL).
For our purpose we shall look at only the SQL. Queries languages have two basic modes of
operation:
•
Terminal Monitor Mode
The user is able to use query language at a terminal, in the same way a command
language interpreter is used. Ad-hoc queries are formulated to obtain data form
databases.
•
Embedded Query Language
The query language statements are included within the code of programs written in
some other programming language, eg. C or Oracle, and effectively because part of
the program, hence the term “embedded query language”.
3.2
STRUCTURED QUERY LANGUAGE (SQL)
Structured Query Language (pronounced sequel in the US; ess-queue-ell elsewhere). A
computer language designed to organise and simplify the process of getting information out
of a database in a usable form, and also used to reorganise data within databases. SQL is most
often used on larger databases on minicomputers, mainframes and corporate servers.
This is an international standard for database query languages and has been adopted by many
computer manufacturers and database product suppliers, e.g. IBM, INGRES, ORACLE,
SYBASE, and INFORMIX.
3.2.1 TABLES
Data in a relational database are stored in tables sometimes called “relations”. A row in a
table corresponds to a single record in a file. Another name for row in a table is “tuple”.
106
Table 9.1 A table called “STUDENT”
Student_ID
Name
Address
date of birth
Boarding
Fees
NOUN/SC/98/01
BINTA ABAKA
KK9 ABIDJAN STR.
22 DEC 1962
800
NOUN/SC/98/02
DULEN KPENETESE
63 ABA RD P/H
15 MAY
1975
1000
NOUN/SC/98/03
UGOMA IFEANYI
3 POLICE STATION RD
22 JAN 1970
300
NOUN/SC/98/04
ADEMOLA RUFA’I
61B BISHOP OLUWOLE STR
22 JUN 1965
450
Source: (French, 2004).
Each row should be uniquely identifiable by a suitable key. The key may either be a simple
key consisting of the value in one column or a composite key consisting of multiple columns.
The example of the table above of the “Student_ID” field is a simple key.
To create a table similar like the one above using SQL statement we use the following syntax;
Create
table student
(
Student_ID
char (13)
not null unique,
Name
char (20)
not null,
Address
char (40)
not null,
date of birth
date,
Boarding Fees
smallint (13)
)
The layout above has been chosen for readability, with the definition of each column in the
table set out on a separate line in the order in which it is to appear in the table.
The explanations of the above statements are as follows;
“Student_ID char (13) not null unique”, states that the first column is to be called
“Student_ID”, it can be up to 13 characters long, it must not be empty “null” and its value
must be unique.
“date of birth”, states that the fourth column is to be called “date of birth”, and its value must
be a date.
107
3.2.2 SELECT STATEMENTS
Every select statement yields a table of values as output and Sometimes there’s only one row
in the table, depending on how you use the command.
select
from
where
group
having
order
into
columns and/or expressions
tables
conditions on the rows
by group rows together
conditions on the groups
by order the rows
temp save results of query in a temporary table
This is used to retrieve values form a table. The following statement retrieves rows from the
table “Student” displaying just the three columns “Student_ID”, “Name” and “Boarding
Fees”. The expression after the word “where” defines what values in a row must have for the
row to be selected.
Select
Student_ID, Name, Boarding Fees
From
Student
Where
Boarding Fees > 400
And
Boarding Fees <1000
Another short syntax is:
Select * from Table where Boarding Fees > 400 and Boarding Fees <1000
This “*” implies ‘everything’ or ‘all records’.
In the above statements the values are Boarding Fees between 400 and 1000 will produces
the table bellow;
Table 9.2 Result of the SELECT Statement
Student_ID
Name
Boarding Fees
NOUN/SC/98/01 BINTA ABAKA
800
NOUN/SC/98/04 ADEMOLA RUFA’I
450
Source: (French, 2004).
108
3.2.3 INSERT STATEMENT
Insert statement is used to add a record into a table, in performing the operation care is taking
not to insert a null value. It has the following syntax;
Insert into Table (Field 1, Field 2, …) Values (‘Value 1’, ‘Value 2’, …)
For example:
Insert into Student (Student_ID, Name, Boarding Fees) Value (‘NOUN/SC/98/01’, ‘BINTA
ABAKA’, ‘800’)
3.2.4 UPDATE STATEMENT
The update statement is used to modify or change values in one or more rows within a table.
It has the following syntax;
Update
Table Set
comput ation where condition
Update
Student
Set
Boarding Fess = Boarding Fess + 250
where
Student_ID = ‘NOUN/SC/98/01’
3.2.5 DELETE STATEMENT
The delete statement is used to remove one or more rows from a table. It has the following
syntax;
Delete From Table Where condition
Delete from Student where Student_ID = ‘NOUN/SC/98/01’
The table means the name of the table in the database such as “Student”, while the condition
states the parameters to consider during execution of the command such as “Student_ID =
‘NOUN/SC/98/01’”.
3.3
OTHER COMMANDS USED WITH THE SQL STATEMENTS
3.3.1 JOIN OPERATIONS
It is possible to retrieve cross referenced data from a number of tables by using the
relationships between the tables. For example;
Select Table.Field 1, Table2.Field 3, … from Table T, Table R where T.Field 1= R.Field
2
109
select
S.Student_ID, S.Name, R.Course_Description, C.CrdUnit
from
Student S, Registration R, Course C
where
R.Student_ID = S.Student_ID
and
R.Course_ID = C.Course_ID
and
CrdUnit = ‘3’
Looking closely to the select statement syntax above, you will notice some abbreviations for
table names like “Student S”, which implies that “S” may be used as a shorthand to represent
the table “Student”. The use of the dot notation after the table name :Student” is used to
specify fields that represents the records in the table. For example “S.Name” means the
Name column in the Student table.
The first join in the query matches the Student_ID in the Registration table with the
Student_ID in the Student table, as shown bellow;
R.Student_ID = S.Student_ID
The second join in the query matches the Course_ID in the Registration table with the
Course_ID in the Course table, as shown bellow;
R.Course_ID = C.Course_ID
Table 9.3 Result of the JOIN Operation
Student_ID
Name
Course_Description
CrdUnit
NOUN/SC/98/01 BINTA ABAKA
Database Organisation
3
NOUN/SC/98/01 BINTA ABAKA
Information System
3
NOUN/SC/98/04 ADEMOLA RUFA’I
Research Methods
3
NOUN/SC/98/04 ADEMOLA RUFA’I
Operation Research
3
Source: (French, 2004).
110
4.0
CONCLUSION
Structured Query Language (SQL), in computer science is a database sublanguage used in
querying, updating, and managing relational databases. It has the ability to manipulate data
from several tables in a single statement as in the JOIN example.
5.0
SUMMARY
In this unit you learnt about:
•
an effective tool called Queries, used to look at just part of the data in a database.
•
Data can be reorder or filter using the Structural Query Language (SQL).
•
SQL is an international standard for database query languages
6.0
TUTOR MARKED ASSIGNMENT
a. What is the mode of operation of a Query language?
b. What does the acronym SQL means? List its statement type
c. What are the two types of queries you know?
d. List the two types of query windows.
7.0
FURTHER READINGS/REFERENCES
•
Elmasri, R., Navathe, S. B. (2004). Fundamentals of Database Systems (4th Edition).
Essex, UK: Pearson Higher Education.
•
French, C. S. (2004). Data Processing and Information Technology, (10th Edition).
London, UK: Thompson Learning.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 15, 2009, from
http://www.jegsworks.com.
111
MODULE 2
UNIT 10:
DATABASES AND COMPUTER NETWORKS
ENTERPRISE DATABASES AND DATA WAREHOUSES
1.0
Introduction................................................................................................................101
2.0
Objectives...................................................................................................................101
3.0
Main Content.............................................................................................................101
3.1
Enterprise Database Structures.......................................................................102
3.2
Client/Server Comput ing................................................................................104
3.3
Databases on The Internet..............................................................................106
3.4
Distributed Databases.....................................................................................106
3.5
Data Warehouses and OLAP..........................................................................108
3.6
People.............................................................................................................109
3.7
Procedures......................................................................................................109
4.0
Conclusion..................................................................................................................110
5.0
Summary....................................................................................................................110
6.0
Tutor Marked Assignment..........................................................................................110
7.0
Further Readings/References.....................................................................................110
112
1.0
INTRODUCTION
In the previous units (7, 8 & 9), you read how data and information are stored using
specialized application software (DBMS) and manipulated using the SQL tool. You will now
learn to identify the reasons organizations choose to share databases.
2.0
OBJECTIVES
By the end of this unit you should be able to:
•
Explain the difference between relational and object-oriented databases and their uses
in business.
•
Describe the differences between schemas, views, and indexes.
•
Differentiate between shared and distributed databases.
•
Discuss database administration procedures and concurrency procedures and explain
why these are an essential part of a shared database system.
3.0
MAIN CONTENT
THE PRINCIPLES OF DATA SHARING
•
Database: A collection of data and information describing items of interest to an
organization.
•
Entity: A person, place, thing, event or condition about which data and information
are collected.
•
Enterprise Database: A collection of data designed to be shared by many users
within an organization.
Figure 10.1 Relationship of DBMS to other Programs in Computer memory.
Source: (Senn, 2004).
113
3.1
ENTERPRISE DATABASE STRUCTURES
Enterprise Data Model/Entity Relationship: A graphical representation of the items (the
entities) of interest about which data is captured and stored in the database.
Figure 10.2
Entity Relationship Model Showing Relations Between Customers and
Orders.
Source: (Senn, 2004).
•
Schema: The structure of a database.
•
Schema for Relational Database
– Relational Database: A database in which the data are structured in a table
format consisting of rows and columns.
Figure 10.3 Schema for Customer-Order Relationship
Source: (Senn, 2004).
114
•
Schema for Object-Oriented Database
– Object-oriented Database: A database that stores data and information about
objects.
– Object: A component that contains data about itself and how it is to be
processed.
– Action/Method: An instruction that tells a database how to process an object
to produce specific information.
Figure 10.4
Classes in an Object Oriented Database Featuring Customer and Order
Objects.
Source: (Senn, 2004).
Views
•
View: A subset of one or more databases, created either by extracting copies of
records from a database or by merging copies of records from multiple databases.
Indexes
•
Index: A data file that contains identifying information about each record and its
location in storage.
•
Record Key: In a database, a designated field used to distinguish one record from
another.
115
Figure 10.5 Using an Index to Retrieve Data
Source: (Senn, 2004).
3.2
CLIENT/SERVER COMPUTING
•
File Server: A computer containing files that are available to all users interconnected
on a local area network.
•
Client/Server Computing: A type of computing in which all data and information
retrieval requests and responses pass over a network. Much of the processing is
performed on the server and the results of the processing are transmitted to the client.
Figure 10.6 Data and Information retrieval Using file Server Computing
Source: (Senn, 2004).
116
Figure 10.7 Multilevel Client/Server Architecture.
Source: (Senn, 2004).
•
Client: In client-server computing, a desktop workstation.
•
Server: A computer that hosts a network and provides the resources that are shared on
the network.
Figure 10.8 Data and Information Retrieval Using Client Server Computing
Source: (Senn, 2004).
117
3.3
DATABASES ON THE INTERNET
•
Web-based Integration: Makes data from enterprise databases available to users
connecting through the Internet (including enterprise intranets and extranets).
Figure 10.9 Web-Enabled Database Processing
Source: (Senn, 2004).
3.4
DISTRIBUTED DATABASES
•
Shared Database: A database shared among many users and applications.
•
Distributed Database: A database that resides in more than one system in a
distributed network. Each component of the database can be retrieved from any node
in the network.
Partitioning and Replication
•
Partitioning: A method of database distribution in which different portions of the
database reside at different nodes in the network.
•
Replication: A method of database distribution in which one database contains data
that are included in another database.
Distribution Strategies
•
Geographic Distribution Strategy: A database distribution strategy in which the
database is located in a region where the data and information are used most
frequently.
118
•
Functional Distribution Strategy: A database distribution strategy in which the
database is distributed according to business functions.
Designed a Distributed Database
•
Database Directory: The component of a shared database that keeps track of data and
information.
•
Other Design Factors: distributed database designers are faced with six factors
beside s the ease of use.
-
Storage Costs: designers must carefully monitor the volume of data in a
distributed database to avoid cost accrued from data duplication..
-
Processing Costs: designers must ensure that database is distributed to only those
who will use it to reduce the cost of processing data.
-
Communication Costs: the cost of distributing data must be justifiable to user
access.
-
Retrieval and Processing: the designer must put into consideration the response
time of access certain information in a database. Since most data will be accessed
from remote locations.
-
Reliability : designers must safeguard both the existence of and access to
important database.
-
Frequency of Updates and Queries: updates to frequently accessed database and
the queries used to access them must be put into consideration during design
process.
Figure 10.10 Functional Distribution of a Database
Source: (Senn, 2004).
119
3.5
DATA WAREHOUSES AND OLAP
•
Online Analytical Processing (OLAP): Database processing that selectively extracts
data from different points of view.
•
Data Warehouse: A large data store, designed from inquiries, that combines details of
both current and historical operations, usually drawn from a number of sources.
•
Data Mining: Uses software designed to detect information hidden in the data.
•
Data Marts: Processed to focus on a specific area of activities or isolated scientific or
commercial processes.
Table : 10.1 Comparison of Enterprise Database and Data Warehouses
ENTERPRISE DATABASE
DATA WAREHOUSE
Subject
Focus
Data are stored with a function or
process orientation
Data are subject oriented, reflecting multiple views of
functions and processes
Temporal
Focus
Data are recorded as current
transactions or to reflect current
events.
Data reflects an historical orientation spanning several
periods of time
Volatile
Updates to data are routine and
may be frequent
Data does not change (i.e., details are read-only).
However, additional dat may be added to the warehouse,
reflecting additional time periods or areas of interest.
Source: (Senn, 2004).
Figure 10.11 Data warehouses and Data Marts Support Analysis and Decision Making
Source: (Senn, 2004).
120
3.6
PEOPLE
The IT professional responsible for managing all the activities and procedures related to an
organization’s database are Database Administrator (DBA) and the Systems Programmer.
3.7
PROCEDURES
A procedure is a step-by-step process or set of instructions for accomplishing a specific
results. Database Administration Procedures are the procedures associated with managing a
database. Some of these procedures are:
–
Database Planning: this includes being aware of and understanding business needs
and user requirements of a database.
–
Database Design: designers must define the records and objects-including the
schema, data names and length that makes up the database.
–
Database Creation: database design is only a framework, but keying in data and
saving on a storage device makes it functional
–
Database Maintenance: database maintenance pertains to the changes made to the
structure and organization of the database. This is caused as a result of an increase in
users’ needs and demand.
–
Analysis of Usage: managing a database means monitoring how and when it is used,
to suggest restructuring to meet new user request.
–
Creation and Monitoring of Security Procedures: developing, implementing, and
monitoring security procedures are important parts of database administration.
Concurrency Procedures
This is the concept of checkmating the type of sharing access to a database resource.
•
Concurrent Data Sharing: A database procedure that allows several users to access
the database simultaneously.
•
Nonconcurrent Data Sharing: A database procedure that allows individuals to access
a database only when no other person or application is processing the data.
•
Record Locking: A concurrency procedure that prohibits another user from accessing
or altering a record that is in use.
•
File Locking: Used in systems that store unstructured information and have file-leve l
sharing.
•
Deadlock: A situation in which each user of a database is waiting for the others to
unlock a record.
121
4.0
CONCLUSION
In a distributed database data can be accessed either centrally from one location or over a
distributed network. The benefit of client/server comput ing is Data and information can be
retrieved easily.
5.0
SUMMARY
In this unit you learnt that:
•
Data Warehouse - combines details of both current and historical database
operations
•
OLAP - view data from different point
•
The IT professional responsible for an organization’s database are Database
Administrator (DBA) and the Systems Programmer
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What are the Concurrency Procedures?
b. List the functions of a DBMS
c. Identify the two most common distribution strategies used for database systems.
Explain
d. What items must be taken into account when designing a distributed database system?
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
122
MODULE 2
UNIT 11
DATABASES AND COMPUTER NETWORKS
COMPUTER NETWORKS
1.0
Introduction................................................................................................................112
2.0
Objectives...................................................................................................................112
3.0
Main Content ……….................................................................................................112
3.1
Types of Network Connection.......................................................................112
3.2
Basic Components of a Network...................................................................113
3.2.1 Network Software…..............................................….........................113
3.2.2 Application Software..........................................................................113
3.2.3 Network Hardware.............................................................................113
3.3
Standards for Networks..................................................................................120
3.4
Networking Checklist.....................................................................................121
4.0
Conclusion..................................................................................................................121
5.0
Summary....................................................................................................................122
6.0
Tutor Marked Assignment..........................................................................................122
7.0
Further Readings/References.....................................................................................122
123
1.0
INTRODUCTION
In Module 1, you read about a computer system, its basic components and how it is used to
process data. In this unit we will discuss how computers can be connected together to share
resources and process data.
2.0
OBJECTIVES
By the end of this unit, you should be able to:
•
Identify the basic components of a network and their uses
•
Types of Networking Connection
•
Basic networking checklist
3.0
MAIN CONTENT
Computer Networking refers to the techniques, physical connections, and programs used to
interlink two or more computers together. This is fundamentally to enable the networked
computers share resources such as hard discs, modems, printers.
3.1
TYPES OF NETWORK CONNECTION
There are two basic types of network connections:
•
Physical connections and
•
Logical or virtual connections
Physical connections that let computers directly transmit and receive signals. Physical
connections are defined by the medium used to carry the signal, the geometric arrangement of
the computers (topology), and the method used to share information.
Logical, or virtual, connections that allow computer applications, such as e-mail programs
and the browsers used to explore the World Wide Web, to exchange information. Logical
connections are created by network protocols and allow data sharing between applications on
different types of computers, such as a personal computer (PC) running the Microsoft
Corporation Windows operating system, in a network. Some logical connections use clientserver application software and are primarily for file and printer sharing. The Transmission
Control Protocol/Internet Protocol (TCP/IP) suite is the set of logical connections used by the
Internet, the worldwide consortium of computer networks.
124
3.2
BASIC COMPONENTS OF A NETWORK
A classical computer network has three essential components or segments. They are as
follows:
•
Network Software.
•
Application Software, &
•
Network Hardware
3.2.1 NETWORK SOFTWARE
This also, consists of computer programs that establish protocols, or rules for computers to
talk to one another. These protocols are carried out by sending, and receiving formatted
instructions of data called packets. Protocols make reasonable connections between network
applications, direct the movement of packets through the physical network, and reduce the
chances of clashes between packets sent at the same time.
3.2.2 APPLICATION SOFTWARE
This consist of computer programs that interface with network users and permit the sharing of
information such as files, graphics, videos, and other resources like printers and disks. The
types of application software are called client-server and peer-to-peer.
Client/Server Application: - Client computers send requests for information or requests to
use resources to other computers in a network, called Servers. Network and web servers
control data and applications commonly. Often, as a network grows and more computers are
added, one computer will act as a server. A server is a central storage point for files or
application programs shared on the network.
An example involves a database that can be accessed via a network. The database is stored on
a network server, along with a portion of the database management system (DBMS). The
DBMS allows users to work with the database. The user’s computer (which can be called the
node, workstation, or client) stores and runs the client portion of the DBMS.
Peer-to-peer: - In a peer-to-peer network, (sometimes called workgroup) you don’t need to
have a dedicated server in your network, because all nodes on the network have equal
relationship to all others. Therefore, computers send messages and requests directly to other
computers of their social class on the network without a Server linkage.
3.2.3 NETWORK HARDWARE
This consists of the computers, nodes and the physical components such as: cables,
connectors and network adapter (Network Interface Card, modem, wireless cards, e.t.c.) that
interconnect them together. Whereas the cables and connectors serve as a pathway for the
smooth flow of electrical signals in-between devices, the network adapter makes it possible
for different computers, with different speeds, voltages and codes to work together, following
a set of rules, or a standard known as a Protocol.
125
Figure 11.1 Basic Components of a Network
Source: (Cisco Networking Essentials, 2009).
A.
NETWORKING DEVICES
i.
Network Interface Cards
Network interface cards (NICs), or adapters, are usually installed inside a computer’s case.
With portable and notebook computers, the NIC is usually in the credit card sized PC card
(PCMCIA) format, which is installed in a slot. Ethernet NICs support only Ethernet
connections, while 10/100NICs can work with either Ethernet or higher-performance Fast
Ethernet connections. In addition, you will need to ensure that your NICs will support the
type of cabling you will use and these are twisted-pair (also called 10BaseT), coaxial (also
called 10Base2), or a mixture of both.
Figure 11.2 Network Interface Cards.
Source: (Google Images, 2009).
126
ii.
Hubs
Hubs, or repeaters, are simple devices that interconnect groups of users. Hubs forward any
data packets they receive over one port from one workstation including e-mail, word
processing documents, spreadsheets, graphics, or print requests to all of their remaining ports.
All users connected to a single hub or stack of connected hubs are in the same “segment,”
sharing the hub’s bandwidth or data-carrying capacity. As more users are added to a segment,
they compete for a finite amount of bandwidth devoted to that segment.
Figure 11.3 Hub.
Source: (Google Images, 2009).
iii.
Switches
Switches are smarter than hubs and offer more bandwidth. A switch forwards data packets
only to the appropriate port for the intended recipient, based on information in each packet’s
header. To insulate the transmission from the other ports, the switch establishes a temporary
connection between the source and destination then terminates the connection when the
conversation is done. As such, a switch can support multiple “conversations” and move much
more traffic through the network than a hub. A single eight-port Ethernet hub provides a total
of 10 megabits per second (Mbps) of data-carrying capacity shared among all users on the
hub. A “full-duplex,” eight-port Ethernet switch can support eight 10-Mbps conversations at
once, for a total data-carrying capacity of 160 Mbps. “Full-duplex” refers to simultaneous
two-way communications, such as telephone communication. With half-duplex
communications, data can move across the cable or transmission medium in just one direction
at a time.
127
Figure 11.4 Switch.
Source: (Google Images, 2009).
iv.
Routers
Routers use a more complete packet “address” to determine which router or workstation
should receive each packet. Based on a network roadmap called a “routing table,” routers can
help ensure that packets are traveling the most efficient paths to their destinations. If a link
between two routers goes down, the sending router can determine an alternate route to keep
traffic moving. Routers also provide links between networks that speak different languages
or, in computer speak networks that use different “protocols.” Examples include IP (Internet
Protocol), the IPX® (Internet Packet Exchange Protocol), and AppleTalk. Routers not only
connect networks in a single location or set of buildings, but they provide interfaces or
“sockets” for connecting to wide-area network (WAN) services. These WAN services, which
are offered by telecommunications companies to connect geographically dispersed networks,
are explained in more detail in the next topic
Figure 11.5 Linksys and Cisco Routers.
Source: (Google Images, 2009).
128
v.
Modems
Modems are used for “dialup” communications; in other words, they dial up a network
connection when needed, and when the transmission is completed, the connection is disabled.
They work with ordinary telephone lines. When you want to send data across telephone lines,
the modem takes the information from digital format and converts it (or modulates it) into an
analog signal. The receiving modem converts the analog signal back into digital form (or
demodulates it) to be read by your computer. This modulating and demodulating gives the
modem its name.
Figure 11.6 A Modem
Source: (Google Images, 2009).
vi.
Bridges
As the network becomes crowded with users or traffic, bridges can be used to break them into
multiple segments. Switches are basically multiple bridges in a single device. Bridges help to
reduce congestion by keeping traffic from traveling onto the network “backbone” (the spine
that connects various segments or “sub networks”). If a user sends a message to someone in
his own segment, it stays within the local segment. Only those packets intended for users on
other segments are passed onto the backbone.
129
Figure 11.7 A Bridge.
Source: (Google Images, 2009).
vii.
Uninterruptible Power Supplies
Uninterruptible power supplies (UPS) are not essential to networks but are highly
recommended. They use constantly recharging batteries to prevent momentary power outages
from shutting down your network servers or clients. Most of them also provide protection
against potentially damaging voltage spikes and surges.
Figure 11.8 A UPS
Source: (Google Images, 2009).
130
viii. Wiring and Cable
Networks use three primary types of wiring (also referred to as “media”):
• Twisted-pair:- the industry standard in new installations. This wire comes in several
“standards.” Unshielded twisted pair (UTP) Category 3 wire (also called 10BaseT) is
often used for your phone lines, and UTP Category 5 (also called 10Base2) wire are
the current networking standards.
• Coaxial:- resembles round cable TV wiring.
•
Fiber-optic:- usually reserved for connections between “backbone” devices in larger
networks, though in some very demanding environments, highly fault resistant fiber
optic cable is used to connect desktop workstations to the network and to link adjacent
buildings. Fiber-optic cable is the most reliable wiring but also the most expensive.
Figure 11.9 The three primary types of Networking cables
Source: (Cisco Networking Essentials, 2009).
B.
Network Management
Network management software allows you to monitor traffic flows, configure new
equipment, and troubleshoot network problems. “Managed” hubs and switches have the
ability to tell network management software “console” how much data they are handling,
sound alarms when problems occur, and record traffic volumes over time to help you
understand when users are placing the heaviest demands on the network throughout the day.
While not essential for very small networks, network management becomes increasingly
important as the network grows. Without it, keeping traffic flowing smoothly throughout the
network, adding or moving users, and troubleshooting problems can be difficult.
C.
Security
Your network is bound to carry at least some information you want to protect from certain
users—students’ grades and attendance records, for example. For this reason, you’ll want to
consider some form of network security. Security solutions come in three basic forms: user
131
authentication and authorization, audits, and firewalls. Authentication designates who can
access the network, and authorization governs what they can see when they’re connected.
Audits enable you to track user activity to help spot unauthorized activity before it becomes a
full-fledged security breach.
D.
Firewalls protect your internal network from invasion through the Internet or other
external sources. Firewalls can restrict access to certain users and control which users can use
which applications when dialing in from outside.
Figure 11.10 A Symbol of a Firewal
Source: (Cisco Networking Essentials, 2009).
3.3
STANDARDS FOR NETWORKS
Communication between interconnected computer systems is a complex activity which takes
place at a number of different levels. At the lowest level there is the physical transmission of
signals and at the highest level there may be communication of messages in everyday
languages.
In an attempt to form a basis for standardizing such interconnections the International
Standard Organisation (ISO) has devised a standard based upon seven distinct levels or
layers of communication. The Open Systems Interconnectivity (OSI) model has seven
layers from the lowest to the highest as follows;
•
The physical control layer is the level of electrical connections, signal transmission
and data in raw form.
132
•
The data link layer is the level at which data is transmitted in small units using
suitable protocols to control and correct transmission. The units of data are “frames”,
that is, asynchronously transmitted characters (i.e. individually at will) or
synchronously transmitted bocks of characters (i.e. fixed intervals at a fixed rate).
•
The network layer is the level which provides control among adjacent sending and
receiving points in a network. The sending and receiving points which are able to
switch transmission are nodes in the network called IMPs.
•
The transport layer is the level which provides an end-to-end service between host
computers. It deals with addressing, error controls and regulated data transfer.
•
The session layer is the level which handles the establishment of connections
between host and the management of the dialogue. Messages created at this level are
addressed by the transport layer and split into packets at the network layer.
•
The presentation layer is the level which handles the standard forms for presenting
data, e.g. the layouts used for VDU displays.
•
The presentation layer is the level which the user has control over in determining
what data is to be transmitted and how it is to be sent or received.
3.4
NETWORKING CHECKLIST
Every network includes:
• at least two computers
•
a network interface on each computer , that is the device that lets the computer talk to
the network. It is usually called a network interface card [NIC] or adapter
•
a connection medium: this is usually a wire or cable, but wireless communication
between networked computers and peripherals is also possible.
•
Network operating system software: such as Microsoft Windows 95 or Windows NT,
Novell NetWare, AppleShare, Linux or Unix.
•
a hub or a switch to act as a connection point between the computers and a router to
connect different networks together.
133
4.0
CONCLUSION
For an ease of communication among computer users, computers need to be conjoined on a
network. A network combines the capabilities of a Computer and other network devices to
share or distribute resources to end users.
5.0
SUMMARY
We learnt in this unit that classical computer network has three essential components or
segments. They’re as follows:
• Network Software.
• Application Software, &
• Network Hardware
6.0
TUTOR MARKED ASSIGNMENT
a.
b.
c.
d.
7.0
What are the Advantages of Using Networks?
What does ISO means? How many layers are there in the OSI?
List the two types of network connection you know.
Why do you join computers and other devices to form a network?
FURTHER READINGS/REFERENCES
•
Cisco Networking Essentials. (2009). Retrieved August 12, 2009, from
http://www.cisco.com/edu
•
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
•
Google Images. (n.d). Retrieved August 2009, from http://www.google.com/images.
134
MODULE 2
UNIT 12
DATABASES AND COMPUTER NETWORKS
NETWORKING TECHNOLOGIES
1.0
Introduction................................................................................................................124
2.0
Objectives...................................................................................................................124
3.0
Main Content…………….........................................................................................124
3.1
A Local-Area Networks (LAN) .....................................................................124
3.2
Wide-Area Networks......................................................................................127
3.3
Wireless Networks.........................................................................................127
3.4
Network Topology.........................................................................................129
3.5
Basic Advantages of Using Networks............................................................131
4.0
Conclusion..................................................................................................................131
5.0
Summary………………………………....................................................................132
6.0
Tutor Marked Assignment..........................................................................................132
7.0
Further Readings/References.....................................................................................132
135
1.0
INTRODUCTION
In Unit 11, you read about the basic devices used in setting up a network. In this unit we will
discuss how these devices can be combined with computers and geometrical be arranged into
two basic technologies local area network (LAN) and wide area network (WAN).
2.0
OBJECTIVES
By the end of this unit, you should be able to:
•
Identify the two network technologies (LAN and WAN)
•
Know what are Network Topologies
•
The concept of wireless networks in LAN and WAN
3.0
MAIN CONTENT
There are basically two types of computer networks namely:
•
Local Area Networks (LAN), and
•
Wide Area Networks (WAN).
Other types of networks co-exist due to the combination of the LAN or WAN networks.
Depending upon the size, computer networks are further classified Metropolitan Area
Networks (MAN), Campus Area Networks (CAN) and Personal Area Networks (PAN). The
topology (topology is the way the computer networks and network resources are connected)
of the networking can be classified as Bus Network, Ring Network and Star Network.
The networking hardware basically consists of wiring, network cards and a hub. Computer
network cards are required so that one computer can understand what the other computer is
“talking”. Network cards have a unique MAC address to identify computers on a computer
network. Hubs connect all the computers in the network. Hubs can also be used to connect to
other hubs to increase the size of the computer network. Two computers can be connected
using Ethernet cards or phone lines or power lines for communication.
(Networks will be treated in details in the next Unit)
3.1
A LOCAL-AREA NETWORKS (LAN)
A Local-Area Networks (LAN) is a network contained in a building or on a single campus.
The first LANs installed are usually basic networking services to support this printer-sharing
requirement. Now a printer anywhere in the local area can be authorized for shared use. The
physical medium to accomplish this connection is the LAN cabling. Each workstation is
connected to a cable that routes the transmission either directly to the next workstation on the
LAN or to a hub point that routes the transmission to the appropriate destination. There are
three primary LAN technologies in use: the Ethernet, Token Ring and High-Speed LAN
Technologies
136
Figure 12.1 A Local Area Network
Source: (Computer Networks, 2009).
Figure 12.2 A Local Area Network in an Advertising Department
Source: (Senn, 2004).
137
Ethernet and Fast Ethernet
Ethernet has been around since the late 1970s and remains the leading network technology
for local-area networks. Ethernet is based on carrier sense multiple access with collision
detection (CSMA/CD). An Ethernet workstation can send data packets only when no other
packets are traveling on the network, that is, when the network is “quiet.” Otherwise, it waits
to transmit, just as a person might wait for another to speak during conversation.
If multiple stations sense an opening and start sending at the same time, a “collision” occurs.
Then, each station waits a random amount of time and tries to send its packet again. After 16
consecutive failed attempts, the original application that sent the packet has to start again. As
more people try to use the network, the number of collisions, errors, and subsequent
retransmits grows quickly, causing a snowball effect. Collisions are normal occurrences, but
too many can start to cause the network to slow down.
Figure 12.3 An Ethernet Network Technology
Source: (Cisco Networking Essentials, 2009).
Token Ring
Token Ring is a “token-passing” technology and an alternative to Ethernet’s collisiondetection method. A token travels through the network, which must be set up in a closed ring,
and stops at each workstation to ask whether it has anything to send. If not, the token
continues to the next point on the network. If there is data to send, the sending station
converts the token frame into a data frame and places it into the ring. The frame continues
around the ring, sets repeated by all stations, but the destination station also copies the frame
into memory. When the frame comes around to the sending station, it strips the data frame
from the ring and releases a new token. Token Ring networks operate at either 4 or 16 Mbps,
138
but with the low cost, ease of use, and easy migration to higher performance in Ethernet
networks. Token Ring is rarely used for new network installations.
High-Speed LAN Technologies
Today’s growing fast-changing networks are like growing communities; the traffic they
create tends to cause congestion and delays. To alleviate these problems, you can install
higher-speed
LAN technologies in your network that move traffic more quickly and offer greater datacarrying capacity than Ethernet.
3.2
WIDE-AREA NETWORKS
Local Area Networks accommodate local users; people within a building or on a campus.
Wide Area Networks connect users and Local Area Networks spread between various sites,
whether in the same city, across the country, or around the world. “Remote access” refers to a
simple connection, usually dialed up over telephone lines as needed, between an individual
user or very small branch office and a central network.
In general, Local Area Networks speeds are much greater than Wide Area Networks and
remote access speeds. For example, a single shared-Ethernet connection runs at 10 Mbps
(mega means “million”). Today’s fastest analog modem runs at 56 kilobits per second (Kbps)
(kilo means “thousand”)—less than one percent of the speed of an Ethernet link.
3.3
WIRELESS NETWORKS
As the number of computers in an office or a home increases, so do the number of cables, so
wireless networking is a viable solution. In wireless networking radio transceivers or infrared
signals are used to communicate between computers and devices. Examples of wireless
networking include Wi-Fi and Bluetooth technology, though there may be security issues
involved in wireless networking. However there definitely is a stronger preference towards
wireless networking nowadays among consumers.
Computer networks have added a new dimension to the 21st century. Today the cyber world
is much faster and wider than the real world. This has all been made possible due to computer
networks. Computer networks have revolutionized business, communication, travel, research,
defense, society and almost all human endeavors. The evolution of computer networks has
helped the technological revolution take a big leap forward.
139
Figure 12.4 A PCMCIA Adaptor used for Wireless networking.
Source: (Computer Networks, 2009).
Wireless networks have become incredibly popular - so much so that virtually all new laptop
computers have wireless network cards included as part of a set of standard features. As a
matter of fact, customers will offer salespeople a strange, blank look if wireless networking is
not included as one of the standard features. People love the convenience of being able to
boot up the laptop and surf the net wherever they may be.
Wireless networks have become so popular and affordable that many people are now opting
to include this convenience in their homes also, then there are a few things that you will need
to understand about how wireless networks work.
Most wireless networking technology available for home use operates on what is called
802.11g technology. What this means is that the data sent over the network is transmitted at
2.4 GHz at a speed of 54 megabits. For non-technical people, that means the data is moving
pretty fast. Newer technology is currently in the works for wireless networks (802.11n), but it
is still in the beta, or testing, phase.
Wireless networks operate by using either modulating radio waves or pulsing infrared light.
They include a router that is hardwired to your Internet connection and transmits data via
these radio or light waves. Your computer receives the information via either an internal or
external wireless adapter, which acts as a receiver.
3.4
NETWORK TOPOLOGY
A network topology is the geometric arrangement or layout of computers in a network. The
following types of layouts are common:
•
Point-To-Point Network Topology
140
•
•
•
•
a.
Bus Network Topology
Star Network Topology
Ring Network Topology, and
Tree Network Topology.
Point-To-Point Network Topology
Point-to-point topology is the simplest, consisting of two connected computers.
Figure 12.5 A Point-To-Point Network Topology
Source: (Computer Networks, 2009).
b.
Bus Network Topology
The bus topology is composed of a single link connected to many computers. All computers
on this common connection receive all signals transmitted by any attached computer.
Figure 12.6 A Bus Network Topology
Source: (Computer Networks, 2009).
141
c.
Star Network Topology
A star topology connects many computers to a common hub computer. This hub can be
inactive, repeating any input to all computers similar to the bus topology, or it can be active,
selectively switching inputs to specific destination computers.
Figure 12.7 A Star Network Topology
Source: (Computer Networks, 2009).
d.
Ring Network Topology
The ring topology uses multiple links to form a circle of computers. Each link carries
information in one direction. Information moves around the ring in sequence from its source
to its destination.
Figure 12.8 A Ring Network Topology
Source: (Computer Networks, 2009).
142
e. Tree Network Topology
A Tree topology combines characteristics of bus and star topologies. It consists of groups
of star-configured workstations connected to a bus backbone cable. Tree topologies allow
for the expansion of an existing network, and enables institutions to configure networks to
meet their needs.
Figure 12.9 A Tree Network Topology
Source: (Computer Networks, 2009).
3.5
•
•
•
•
•
•
4.0
BASIC ADVANTAGES OF USING NETWORKS
There are many possible advantages of using networks. The basic ones are:
The sharing of resources (e.g computers and staff) and information
The provision of local facilities without the loss of central control
The even distribution of work, processing loads, e.t.c.
Shared risk and mutual support.
Improved and more economic communication facilities in general, e.g. including
voice communications.
CONCLUSION
A network topology is the geometric arrangement or layout of computers in a network that
form the two basic networking technologies (LAN and WAN). The wireless network is not a
separate technology but it used to extend the capabilities of the local area network and wide
area network to reduce or eliminate cabling.
143
5.0
SUMMARY
We learnt in this unit that:
• Local Area Networks speeds are much greater than Wide Area Networks
• There are other types of WAN – (MAN, PAN and CAN)
• A wireless network can be added to either a LAN or a WAN to reduce cabling
• Examples of wireless networking include Wi-Fi and Bluetooth technology
6.0
TUTOR MARKED ASSIGNMENT
a.
b.
c.
d.
7.0
Identify the types of Network Technology?
What is Network Topology?
Which type of wide area network is faster than the local area network?
Define high speed LAN.
FURTHER READINGS/REFERENCES
•
•
Cisco Networking Essentials. (2009). Retrieved August 12, 2009, from
http://www.cisco.com/edu
Cohn, Z., Lefolii, S. (1998). An Illustrated Dictionary of Information Technology.
Lewes, UK: Godfrey Cave Associates Ltd.
•
Computer Networks. (2009). Retrieved August 12, 2009, from
http://www.businesslifehome.com/?computer+network
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
144
MODULE 3
UNIT 13
DISTRIBUTED NETWORKS AND THE INTERNET
COMMUNICATIONS NETWORKS
1.0
Introduction................................................................................................................133
2.0
Objectives...................................................................................................................133
3.0
Main Content.............................................................................................................133
3.1
Principles of Communications Networks…...................................................133
3.2
Role of Communications Networks...............................................................133
3.3
Network Service Applications.......................................................................134
3.4
Network Channels..........................................................................................135
3.5
Communication Channels For WANS, MAN and LANS.............................136
3.6
Physical Network Transport Technology.......................................................141
4.0
Conclusion..................................................................................................................144
5.0
Summary....................................................................................................................144
6.0
Tutor Marked Assignment..........................................................................................144
7.0
Further Readings/References….................................................................................145
145
1.0
INTRODUCTION
Unit 12 introduced you to computer networks. This unit will expand the computer networks
to communication networks by adding communication channels.
2.0
OBJECTIVES
By the end of this unit you should be able to:
•
State the principles of communication networks.
•
Identify the various types of network service applications
•
State the various network channels with examples.
•
Identify the five transport technologies that are in widespread use in physical channel
networks.
3.0
MAIN CONTENT
A communication network is a set of locations, or nodes, consisting of hardware, programs,
and information that are linked together as a system that transmit and receives data and
information.
3.1
PRINCIPLES OF COMMUNICATIONS NETWORKS
•
Communication: The sending and receiving of data and information over a
communications network.
•
Multiuser System: A communications system in which more than one user share
hardware, programs, information, people, and procedures.
3.2
ROLE OF COMMUNICATIONS NETWORKS
•
Communications Network: A set of locations, or nodes, consisting of hardware,
programs, and information linked together as a system that transmits and receives data
and information.
•
Node: A communication station within a network.
146
3.3
NETWORK SERVICE APPLICATIONS
Network Services are the applications available on a communications network.
•
Electronic Mail: sometime called e-mail are designed to overcome the
communication barrier created by time and distance over a phone. E-mail is a service
that transports text messages from a sender to one or more receivers.
– Electronic Mailbox: An area of space on magnetic disk in a server or host
computer that is allocated for storing an individual’s e-mail.
Figure 13.1 E-mail Network and Mailboxes
Source: (Senn, 2004).
•
Voice Mail: A system that captures, stores, and transmits spoken messages using an
ordinary telephone connected to a computer network.
– PPTs (post, telephone, and telegraph companies): A general term for
telephone companies outside the United States.
– Unified Messaging Systems: Offers users the ability to manage several
communications media, including telephone, fax, e-mail (including those from
the Web), and voice mail through a central message manager.
147
Figure 13.1 How Voice Mail Works
Source: (Senn, 2004).
•
Videoconferencing: A type of conferencing in which video cameras and microphones
capture the sight and sound of participants for transmission over a network.
– Webcasting: Uses the reach of the Internet to link people from anywhere in
the world into a conference.
•
Work Group Conferencing: A type of conferencing that uses a software package
called groupware to interconnect participants’ computers at their various locations.
Participants interact through a microcomputer directly linked to a server and their
comments are broadcast to all others taking part in the conference.
•
Electronic Bulletin Board: A network service application that allows messages and
announcements to be posted and read. It is accessed by dialing a telephone number
and interconnecting with the bulletin board through a modem.
•
Electronic Funds Transfer (EFT): The movement of money over a network.
148
Figure13.3 ATM Networks Link Regional, National, and International Banks.
Source: (Senn, 2004).
•
Electronic Data Interchange (EDI): A form of electronic communication that allows
trading partners to exchange business transaction data in structured formats that can
be processed by application software.
•
Videotex: A two-way, interactive, text-only service operating on mainframe
computers that combines a video screen with easy-to-follow instructions.
3.4
NETWORK CHANNELS
Communications Channel/Communications Medium is the physical or cableless media that
link the different components of a network.
•
Physical Channels:
– Twisted Pair: A physical communications channel that uses strands of copper
wire twisted together in pairs to form a telephone wire.
– Coaxial Cable/Co-ax: A physical communications channel that uses one or
more central wire conductors surrounded by an insulator and encased in either
a wire mesh or metal sheathing.
– Coaxial Cable/Co-ax:
149
•
Baseband Cable: Carries a single communication or message at very
high megabit speeds, is often used in local area networks.
•
Broadband Cable: Carries multiple signals – data, voice, and video –
simultaneously; each signal can be a different speed.
– Fiber-optic Cable: A physical communications channel that uses light and
glass fibers.
•
Wireless Channels
Wireless channels transmit data using radio signals sent through air or space rather than over
wire or optical cables.
– Microwave: A cableless medium that uses high-frequency radio signals to
send data or information through the air.
Figure 13.4 A Microwave Station
Source: (Smith, 2009).
– Satellite: A cableless medium in which communications are beamed from a
microwave station to a communications satellite to orbit above the earth and
relayed to other earth stations.
•
Low-earth-orbit satellite (LEO): Because they circle Earth at a
distance far closer than other satellites, LEO satellite systems offer
significant advantages: they do not have the comparatively long
propagation delays, do not require use of bulky, expensive, directional
antennas, less expensive to produce and to launch into orbit. However,
greater numbers are needed to provide coverage for a geographic
because they do orbit closer to Earth.
•
Very Small Aperture Terminal (VSAT): A satellite earth station with
an antenna diameter of under one meter.
150
Figure 13.5 A Very Small Aperture Terminal (VSAT).
Source: (Smith, 2009).
– Infrared: A cableless medium that transmits data and information in coded
form by means of an infrared light beamed from one transceiver to another.
•
Transceiver: A combination transmitter and receiver that transmits and
receives data and information.
– Radio Waves
•
3.5
Radio Wave Transmission/Radio Frequency (RF) Transmission: A
cableless medium that uses frequencies rented from public radio
networks to transmit data and information.
COMMUNICATION CHANNELS FOR WANS, MAN AND LANS
•
Public Access Networks: A network maintained by common carriers for use by the
general public.
– Switched Network/Circuit Switched: The complete set of public access
networks, so named because the telephone company operates and maintains
the switching centers that make it possible to transmit data and information.
– Packet Switching: A network communication method in which messages are
divided into packets. Each packet is then transmitted individually and can even
follow different routes to its destination.
– Packet: A piece or section of a transmitted message that contains both data
and address information enabling the network to deliver the packet to its
intended destination.
151
•
Private Network: A network made up for leased (dedicated) communications lines.
– Leased Line/Dedicated Line: A communications line reserved from a carrier
by a company for its exclusive use.
– Value-added Network (VAN): A public data communications network that
provides basic transmission facilities plus enhancements (e.g. temporary data
storage and error detection).
Connecting to the Channel
The devices used as channels to connect to networks are:
•
Modem: A device that connects a computer to a communications medium and
translates the data or information from the computer into a form that can be
transmitted over the channel. Used in WANs.
•
Multiplexer: A device that converts data from digital to analog form and vice versa in
order to allow a single communications channel to carry simultaneous data
transmissions from the many terminals that are sharing the channel.
•
Network Interface Card (NIC): A circuit board used in LANs to transmit digital data
or information.
Figure 13.6 Converting Digital Signal to Analog Signal using a Modem.
Source: (Senn, 2004).
152
Interconnecting Networks
•
Bridge/Router: A device that interconnects compatible LANs.
•
Gateway: A device that connects two otherwise incompatible networks, network
nodes, or devices.
Extending Networks
•
Microwave/RF Radios
•
Switch
•
Hub
3.6
PHYSICAL NETWORK TRANSPORT TECHNOLOGY
Five Types of Transport Technology
•
Frame Relay: A way of sending data over a wide area network in which data are
divided into frames (i.e., packets) with each containing an address that the switched
network uses to determine its destination.
•
Asynchronous Transfer Mode (ATM): A data transmission method using switched
networks in which a message containing data, voice, or video is divided into fixed
length cells.
Figure 13.7 Frame Relay Network.
Source: (Senn, 2004).
153
Figure 13.8 Asynchronous Transfer Mode (ATM):
Source: (Senn, 2004).
•
Digital Subscriber Line (DSL): Offers high-speed data access over the single pair of
the ordinary copper lines used with basic voice-grade telephone service.
– Asymmetric Digital Subscriber Line (ADSL): The most commonly used form
of high speed digital subscriber line (DSL) Internet access characterized by
higher receiving (upstream) transmission rates compared to sending
(downstream) transmissions.
– Very High Speed DSL (VDSL): Provides transport of data over copper
twisted pair lines at even higher speeds, ranging from 13 mbps to 55 mbps.
154
Figure 13.9 A digital subscriber line provides high-speed data transmission over ordinary
copper telephone lines.
Source: (Senn, 2004).
•
Integrated Services Digital Network (ISDN): A next generation telephone system
integrating voice and data onto one line and capable of transporting digital data over
analog lines.
•
Switched Multimegabit Data Services (SMDS): A high-speed, packet-switched
transport technology that can operate over copper or fiber channels.
Figure 13.9 Integrated Services Digital Network.
Source: (Senn, 2004).
155
Figure 13.10 Switched Multimegabit Data Service.
Source: (Senn, 2004).
4.0
CONCLUSION
A Communications Channel/Medium is used to physically or wireless link the different
component of a communication networks for the benefit of sharing various network service
applications (e-mail, e-conference, e-transfer).
5.0
SUMMARY
In this unit you learnt that a communication network is made up of:
6.0
•
Interconnecting networks - using a router, bridge and gateway.
•
Extended networks - using Microwave/RF radio, switch and hub.
•
Physical Channels: Twisted Pair, Co-ax and Fiber-optic Cable.
•
Wireless Channels: Microwave, Satellite, Radio Frequency (RF) Transmission.
TUTOR MARKED ASSIGNMENT (TMA)
a. What is a communication network?
b. List three network service applications you know.
c. What do you understand by the term network channels?
d. List the five Types of Transport Technology you know
156
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 15, 2009, from
http://www.jegsworks.com.
157
MODULE 3
UNIT 14
DISTRIBUTED NETWORKS AND THE INTERNET
ENTERPRISE AND WIRELESS COMMUNICATIONS NETWORKS
1.0
Introduction................................................................................................................147
2.0
Objectives..................................................................................................................147
3.0
Main Content.............................................................................................................147
3.1
Wireless Communications Networks.............................................................147
3.2
Network Operating Systems...........................................................................150
3.3
Enterprise Architectures................................................................................150
4.0
Conclusion………………………………..................................................................153
5.0
Summary....................................................................................................................153
6.0
Tutor Marked Assignment..........................................................................................153
7.0
Further Readings/References….................................................................................153
158
1.0
INTRODUCTION
Unit 13 introduced you to communication networks. In this unit you will learn more about the
wireless communication networks and the enterprise (Organizations).
2.0
OBJECTIVES
By the end of this unit you should be able to:
•
Describe the four forms of wireless communications.
•
Explain the role of a network operating system.
•
Discuss the activities involved in network administration.
•
Explain the three types of enterprise architectures and the advantages offered by each.
3.0
MAIN CONTENT
3.1
WIRELESS COMMUNICATIONS NETWORKS
Wireless communication has gained a lot of interest for a wide range of ICT applications. The
four wireless forms of interest are:
–
Cellular Communication Service
–
Wireless LAN (WLAN)
–
Bluetooth Personal Area Network/Personal Area Network
–
Wireless Data Networks
A
CELLULAR COMMUNICATION SERVICE
•
Cellular Communications Service: A wireless technology that transmits radio
messages between a mobile device (such as mobile telephone, PDA, or wireless
laptop) and a cell site.
•
Cellular Radio System
– Mobile Telecommunications Switching Office (MTSO): The switch used in a
cellular (mobile) telephone system that links the cell tower to a traditional
telephone switch in the public switched telephone network (PSTN).
159
Figure 14.1 A Cellular Radio System
Source: (Senn, 2004).
•
Analog and Digital Cellular Service
– Time Division Multiple Access (TDMA): A digital cellular transmission
technology that divides a radio frequency into time slots and then allocates
slots to an individual device’s conversation or message, thereby distinguishing
it from other transmissions.
– Code Division Multiple Access (CDMA): A digital cellular transmission
technology that encodes each device’s conversation or message with a unique
identification code to distinguish it from other transmissions.
•
Next Generation Cellular Service
– Generalized Packet Radio Service (GPRS): GPRS (or 2.5G) features higher
speed transmission rates than preceding telecom generations and uses packet
switching rather than circuit switching, to transmit messages.
– Third-generation Service (3G): Uses packet switching and transmits at higher
bandwidths that provide faster downloads of information – rates ranging from
384 Kbs to 2 Mbs, depending on the location of the user
– Global Positioning System (GPS): A satellite navigation system and a
worldwide navigation system that uses information received from orbiting
satellites
160
B
WIRELESS LAN (WLAN
Local area networks that transmit data using radio frequencies instead of cables.
– Components
•
Access Point: A device that converts wired LAN signals into radio
frequency.
•
802.11 Wireless Ethernet
– Wireless LAN Security
C
•
Wired Equivalent Privacy (WEP): A system of security protection that
is a standard for encrypting data (converting the data into a protective
code) over an 802.11 b wireless network.
•
Service Set Identity (SSID): An encrypted code keyed into the LAN
devices, so that only devices with similar code can access the network
resources.
BLUETOOTH PERSONAL AREA NETWORK/PERSONAL AREA
NETWORK
A wireless technology for communicating between devices that enable short-range radio links
(30 feet or 10 meters) between devices, such as between a PC and a laptop, or a PDA and a
printer.
D
WIRELESS DATA NETWORKS
•
Wireless Data Networks (WDNs): Networks that use cellular communications
services to support mobile users seeking to interconnect with networks using wireless
laptops and PDAs.
•
Virtual Private Network (VPN): A network constructed of public channels to connect
client computers to server, incorporating encryption and other security mechanisms to
ensure that only authorized users can gain access and that the data cannot be
intercepted
161
Figure 14.2 A Virtual Private Network Architecture
Source: (Senn, 2004).
3.2
NETWORK OPERATING SYSTEMS
Network Operating System (NOS): A software program that runs in conjunction with the
computer’s operating system and applications programs and manages the network.
•
Protocol and Communications Control
– Protocol: The rules and conventions guiding data communications, embedded
as coded instructions in the network software.
•
Network Administration/Network Management: The management of a network,
consisting of those procedures and services that keep the network running properly.
The ICT professional responsible for this job is called a Network Administrator.
3.3
ENTERPRISE ARCHITECTURES
Architecture: The structure of a communications network, which determines how the various
components of the network are structured, how they interact, and when cooperation between
the system’s components is needed.
Centralized Architecture
•
Centralized Architecture: A communications architecture in which a computer at a
central site hosts all of the network’s hardware and software, performs all of the
processing, and manages the network.
162
•
Host-based Computing: Centralized computing.
•
Teleprocessing: The processing capability made possible by connecting desktop
computers to a remote computer through telephone lines.
•
Front-end Computer: In a centralized system, a minicomputer loaded with specific
programs to handle all incoming and outgoing communications traffic.
Figure 14.3 A Centralized Architecture
Source: (Senn, 2004).
Distributed Architecture
•
Distributed Architecture: A communications architecture in which the computers
reside at different locations and are interconnected by a communications network.
•
Distributed Processing: Processing in which an application runs on one or more
locations of the network simultaneously.
•
Distributed Database: A database that resides in more than one system in a
distributed network. Each component of the database can be retrieved from any node
in the network.
163
Figure 14.4 A Distributed Architecture with Distributed Processing
Source: (Senn, 2004).
Combining Architectures
•
Hybrid Network: A communications architecture that combines centralized and
distributed architectures to take advantage of the strengths of both.
•
Virtual Company: A company that joins with another company operationally, but not
physically, to design and manufacture a product.
Figure 11.14
Figure
Figure 14.5 Hybrid Architecture
Source: (Senn, 2004).
164
4.0
CONCLUSION
Wireless communication networks are mostly used to implement enterprise networks,
because it is easier and faster to connect branch offices at different cities over a wide distance
to share resources.
5.0
SUMMARY
In this unit you learnt about:
•
•
the four types of wireless communication networks
–
Cellular Communication Service
–
Wireless LAN (WLAN)
–
Bluetooth Personal Area Network/Personal Area Network
–
Wireless Data Networks
the three types of Enterprise Architectures
–
Centralized Architecture
–
Distributed Architecture
–
Combining Architectures (Hybrid Network: combines centralized and distributed
architectures )
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. What is security in WLAN
b. List the four types of wireless communication networks
c. Who is a Network Administrator?
d. How many types of Enterprise Architectures do you know?
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
165
MODULE 3
UNIT 15
DISTRIBUTED NETWORKS AND THE INTERNET
ESSENTIALS OF THE INTERNET
1.0
Introduction................................................................................................................155
2.0
Objectives...................................................................................................................155
3.0
Main Content..............................................................................................................155
3.1
The Internet........................................….......................................................155
3.01 Basic Concepts......................................................................................155
3.2
The Origins of the Internet.............................................................................156
3.3
Computers on the Internet..............................................................................156
3.4
Capabilities of the Internet….........................................................................157
3.5
The Internet Community................................................................................159
3.6
Organisational Internet: Intranets and Extranets…........................................161
4.0
Conclusion..................................................................................................................162
5.0
Summary....................................................................................................................162
6.0
Tutor Marked Assignment............................................………………......................162
7.0
Further Readings/References.....................................................................................162
166
1.0
INTRODUCTION
In Unit 13 and 14, you learnt about enterprise and personal communication networks. In this
unit you would use these networks to implement the Internet. The internet is a giant highway
that connects you to millions other people and organizations located throughout the world. It
is considered to be the most important technology of the 21st century.
2.0
OBJECTIVES
•
•
•
•
Discuss the origin and uses of the Internet
Describe the three types of capabilities of the Internet.
Identify the principal communication and retrieval capabilities of the Internet.
Know the difference between Intranets, Extranets and Internet.
3.0
MAIN CONTENT
A network is a communication system connecting two or more computers. Networks connect
people as close as the next office and as far away as halfway around the world. The largest
network in the world is the Internet. The internet is a huge computer network available to
nearly everyone with a microcomputer and a means to connect to it.
3.1
INTERNET
The internet is often referred to as the information Superhighway; it is like a highway that
connects you to millions of other people and organizations. Unlike typical high ways that
move people and things from one place to another, the internet moves your ideas and
information. Rather the moving through geographic space, you move through cyberspace-the
space of electronic movement of ideas and information.
3.01 BASIC CONCEPTS
a.
Connectivity
Connectivity is the capability of your microcomputer to share information with other
computers. Data and information can be sent over telephone lines or cable and through air.
This means that, your microcomputer can be connected to other computers, to the internet,
and too many computerized data banks and other sources of information worldwide.
The most dramatic change in connectivity in the past decade has been the widespread use of
mobile and wireless communication devices. It was used in the past for telephone
communications, these devices are widely used to connect people and computers located
almost anywhere in the world.
b.
Wireless Revolution.
The telephone, mobile and wireless communication systems are the beginning of wireless
revolution, a revolution that is expected to dramatically affect the way we communicate and
use computer technology. Connectivity and the wireless revolution are significant
167
developments, for they expand the uses of the microcomputer several fold. Central to the
concept of connectivity is the network or computer network.
3.2
THE ORIGINS OF THE INTERNET
The Internet, or the Net, was launched in 1969 when the United States funded a project that
developed a national computer network called Advanced Research Agency Network
(ARPANET). The Internet is a large network that connects smaller networks all over the
globe together.
3.3
COMPUTERS ON THE INTERNET
•
Client Computer: The computer that accesses the information stored on a server
computer.
•
Server Computer: The computer that contains data and information that can be
accessed by a client computer.
•
Client-server Computing: A type of computing in which all data and information
retrieval requests and responses pass over a network. Much of the processing is
performed on the server and the results of the processing are transmitted to the client.
•
Surf or Surfing: Moving among a number of networks that are linked together, or
inter-networked.
Figure 15.1 Structure of the Internet
Source: (Senn, 2004).
168
Figure 15.2 Client / Server Comput ing
Source: (Senn, 2004).
3.4
CAPABILITIES OF THE INTERNET
The Internet is used by billion of users in different countries in the world to perform the
following activities;
a. Communicate
b. Retrieve
c. Research on the Web
d. Shopping or Cybermalls
a.
Communications Capabilities
•
E-mail or Electronic Mail: A service that transports text messages from a sender to
one or more receivers via computer.
•
Mailing Lists: Each mailing list has subscribers who receive messages as part of an
ongoing discussion of the list’s topic.
– Moderated: A mailing list in which the messages are first screened by an
individual to determine their suitability given the purpose of the list.
•
Newsgroups: Worldwide discussion areas where notices can be posted for anyone to
view.
– Usenet or User’s Network: A system of worldwide discussion groups, not an
actual physical network.
– Netiquette: A list of simple newsgroup guidelines that keep people from
making mistakes.
169
•
Chat Session or Internet Relay Chat (IRC): A live interactive discussion in which
parties on the network exchange ideas and observation electronically.
– Portal: A gateway or hub site, such as Yahoo!, that provides chat rooms.
•
Instant Messages: A combination of real-time chat and e-mail by which short text
messages are rapidly exchanged over the Internet, with messages appearing on
recipient’s display screen immediately upon arrival.
•
Internet Telephony or Voice Over the Internet or Voice over IP: Real-time voice
conversations transmitted between computers on the Internet.
•
Telnet: A network capability that permits remote sign-on to any computer on the
Internet from the computer an individual is using at that time.
b.
Retrieval Capabilities
•
FTP (File Transfer Protocol): Used for transferring files containing documents or
software between computers on the Internet.
•
Web Directory: A listing of Web sites and their URLs, categorized by topic.
– Keyword: A string of letters or words that indicates the subject to be searched.
•
Search Engines: Software programs that look through the Web to locate sites
matching a keyword entered by the user. They provide two different search
approaches: Keyword and Directory search. Examples include Yahoo, Google, Alta
Vista, Ask, My Search, and others.
• Metasearch Engines: The metasearch engine receives the results, eliminates
duplicates, orders the hits, and then provides edited list to you. Metacrawler is
an example of metasearch engine.
•
•
Specialised Search Engines: This focused on subject specific Web sites
(www.invisibleweb.net), they save time by narrowing the search. When
researching for information on production or engineering. You could begin
with a general search engine like Google or go directly to howstuffworks.com.
Portal: A gateway or hub on the Internet from which other sites can be visited.
– Vertical Portal or Vortal: A Web site that specializes in providing
information related to a particular industry such as automobiles, healthcare, or
investments.
– Horizontal Portal: Provides services and links to Web sites of interest to a
wide variety of users.
•
Webcasting: The prearranged delivery, or push, of information of interest to a user’s
desktop automatically.
170
– Pull: To get something from a Web site by clicking on a link or entering a
URL.
– Push: The capability of a Web site for automatic Internet delivery of
information, including software updates, to a user’s desktop.
– Channel: A Web site designed to push information to a user’s desktop.
•
Streaming: An on-demand retrieval and playing of audio, video, or other media that
can occur while the downloading is occurring.
c.
Research on the Web
The Web being an invaluable research tool for materials to write thesis, has three basic
procedures: locating information, evaluating the information and citing references.
• Locating information: with all the numerous information available on the
Web, it is very difficult for you to locate the right material you are looking for.
Discussion groups (www.liszt.com) that can link you to experts are being
overlooked.
–
Evaluating the information: locating information is not all because not everything
you find on the Web is useful, nearly anyone can publish anything. Care is to be taken
when considering the quality of information by considering a few common sense
questions, like, who put the information there and what are the sources. For example
if the site is maintained by a university, college, or government agency, the
information is likely to be more reliable than information from an unknown
individual.
– Citing references: Plagiarism is the illegal copying of someone else’s words or ideas.
You can use someone’s words or ideas without committing plagiarism by simply
acknowledging or citing the source.
Author Name, day month year, <sources>
Binta Musa, 22 December 2008,http://www.billytuks.com
This citation acknowledges information created by Binta Musa (author) that was
obtained on December 22, 2008, from http://www.billytuks.com Web site <source>.
If the authors name is unknown the title of the Web page would replace the author’s
name.
d.
•
Shopping or Cybermalls
Electronic Commerce/e-commerce: Conducting commercial activities on the
Internet. (Will be discussed in details in unit 17)
3.5
THE INTERNET COMMUNITY
The way you connect a phone to a telephone system that is how you connect a computer to
the Internet. The computer becomes an extension of a giant network of computers with
branches all over the world that allow the use of a browser program to the Web.
171
a.
Internet Users – you, organizations, schools, hospitals, e.t.c
b.
Providers - The providers or host computers provide a path or connection for
individuals to access the Internet. The National Open University of Nigeria (NOUN)
most likely provides free internet access to staff and students either through their local
area network or a dial-up or telephone connection. They provide connection to the
users through the following technologies including dial-up, DSL, cable, and wireless
modems.
The follow are Companies that act as providers in different capacities:
•
Service Providers or Internet Service Providers (ISPs): A company that sells
communications services that enable users to access the Internet.
– National services providers: through standard telephone connections users can
access the internet from almost anywhere within the country for a standard fee
without incurring long distance telephone charges. They are Nigerian
Telecommunication (NITEL), American Online (AOL) and GSM companies.
– Regional services providers: they also use telephone lines known and also
fixed wireless system, but the coverage is not as wide as the national service
providers. They cover several states. If the user accesses the internet from
outside the regional area they incur long distance connection charges in
addition to the service’s standard fees. Intercellular, Multilinks, Starcoms,
Visafone, e.t.c
– Wireless services providers: they do not use telephone lines but rather use
microwave radio, Vsat and other satellite technologies. They provide
connections for computers with wireless modems and a wide array of wireless
devices. They include MicroAccess ltd, Linkserve, Propercom, IntelSat, Direct
on Pc, GSM Companies, e.t.c.
•
Application Service Providers (ASPs): Companies that develop, install, and operate
(or host) an information technology application on the Internet for the user, charging a
recurring fee for doing so.
•
Content Providers: Individuals or companies that furnish the information available on
the Internet.
– Content: Information distributed over the Internet.
•
Infrastructure Providers
– Network Infrastructure Providers: Companies, such as telephone, cellular
telephone, cable TV, and satellite transmission companies, that operate the
network of communication channels that carry data and information to and
from user and content locations.
172
– Component Infrastructure Providers: Companies that supply the computer
hardware and software that makes it possible to use, operate, or store and
retrieve content from the Internet.
•
Internet Support Agencies
– Internet Corp. for Assigned Names and Numbers (ICANN): The nonprofit
corporation that was formed to assume responsibility for the IP address space
allocation, protocol parameter assignment, domain name system management,
and root server system management.
– Internet Engineering Task Force (IETF): A large international community
of network designers, operators, vendors, and researchers concerned with the
evolution of Internet architecture and the smooth operation of the Internet.
3.6
ORGANISATIONAL INTERNET: INTRANETS AND EXTRANETS
Computer networks in organisations have evolved over time. Most large organisations have a
complex and wide range of different network configurations, operating systems, and
strategies. Integrating or connecting all of these has been very challenging task. One way is to
apply Internet technologies to support communication within and between organisations
using intranets and extranets.
Intranets
An intranet is a private network within an organisation that resembles the Internet. Like the
public Internet, intranets use browsers, Web sites, and Web pages. Intranets typically provide
e-mail, mailing list, newsgroup, and FTP services accessible only to those within the
organisation.
Organisations use intranets to provide information to their employees. Typical applications
include electronic telephone directories, e-mail addr esses, employee benefit information,
internal job openings, and much more. Employees find surfing their organizational intranets
to be easy and as intuitive as surfing the Internet.
Extranets
An extranet is a private network that connects more than one organisation. Many
organisations use Internet technologies to allow suppliers and others limited access to their
networks. The purpose is to increase efficiency and reduce costs. For example, General
motors have thousands of suppliers for the parts that go into an automobile. By having access
to the production schedules, suppliers can schedule and deliver parts as they are needed at the
General motors assembly plant. General motors can be assured of having adequate parts
without maintaining large inventories.
173
4.0
CONCLUSION
The internet is the actual physical network. It is made up of wires, cables, and satellites.
Being connected to this network is often described as being Online. The Internet connects to
over 100 million computers and resources worldwide. The internet has changed the world
into a global village.
5.0
SUMMARY
You learnt in this unit that:
• The Internet is the world’s largest network.
• the internet is made up of a community of end-users and providers.
• the Internet is used to Communicate, Retrieve, Research and E-Commerce
6.0
TUTOR MARKED ASSIGNMENT (TMA)
a. Identify the main functions of the Internet.
b. When was the Internet launched and by who?
c. What is the difference between e-mail, instant message, and chat session?
d. What is the difference between Intranets, Extranets and Internet?
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
174
MODULE 3
UNIT 16
DISTRIBUTED NETWORKS AND THE INTERNET
WORLD WIDE WEB
1.0
Introduction................................................................................................................164
2.0
Objectives...................................................................................................................164
3.0
Main Content..............................................................................................................164
3.1
The Origins of the Web..................................................................................164
3.2
Internet Addresses..........................................................................................164
3.2.1 Domain Name System.......................................................................165
3.2.2 Addresses On Host Computers...........................................................166
3.3
E-Mail or Electronic Mail..............................................................................167
3.4
Browsing the World Wide Web.....................................................................168
3.5
Web Utilities...................................................................................................171
4.0
Conclusion.................................................................................................................171
5.0
Summary....................................................................................................................172
6.0
Tutor Marked Assignment.........................................................................................172
7.0
Further Readings/References.....................................................................................172
175
1.0
INTRODUCTION
In the Unit 15, you learnt about the Internet changing the world into a global village. In this
unit you will learn how to use the Web; a multimedia interface to resources available on the
internet
2.0
OBJECTIVES
•
•
Discuss the origin Web.
Summarize how the Internet knows the location of a particular user.
•
Explain the purpose of hyperlinks and their role on the Web.
•
Describe the characteristics of browser software and relate them to the types of
information that can be included in a home page.
3.0
MAIN CONTENT
The web, also known as the World Wide Web or WWW or W3, provides a multimedia
interface to the numerous resources available on the internet. The web provides an easy to
use, exciting, multimedia interface to connect to the internet and to access the resources
available in cyberspace. It has become an everyday tool for all of us to use.
3.1
THE ORIGINS OF THE WEB
The Web also known as the WWW and the World Wide Web was introduced in 1992 at the
Center for European Nuclear Research (CERN) in Switzerland. Prior to the Web, the internet
was all text (no graphics, animations, sound, or video). The Web made it easy to include
these elements.
3.2
INTERNET ADDRESSES
Figure 16.1
[email protected]
Figure 16.1 Internet Address
Source: (Senn, 2004).
176
3.2.1 DOMAIN NAME SYSTEM
Domain Name System (DNS): Computers have numeric addresses consisting of strings of
numbers known as their Internet protocol (or IP) address.
•
Domain Name: The familiar, easy-to-remember names for computers on the Internet
that correlate to assigned IP addresses.
•
Registry: A regional organization that allocates Internet addresses to requestors in that
region.
•
Registrars: Organizations delegated to accept and process Internet address
applications and submit approval applications to the regional registrar.
•
Root Servers: One of 13 special computers distributed around the world that maintain
the Internet addresses for all global and country registries.
Figure 16.2 Basic DNS Registry Structure
Source: (Senn, 2004).
177
Figure 16.3 Internet Domain Names
Source: (Senn, 2004).
3.2.2 ADDRESSES ON HOST COMPUTERS
•
E-mail Addresses
•
World Wide Web Addresses
– Uniform Resource Locator (URL): A document’s address on the WWW.
•
FTP Addresses
178
•
World Wide Web (WWW) or the Web: The set of interconnected electronic
documents, or Web pages, that are linked together over the Internet.
– Web Pages: Interconnected electronic documents.
– Hyperlinks: Words and/or symbols highlighted by blinking, color, or
underline that connect one document to another related document on the Web.
Figure 16.4 Hyperlink Structure
Source: (Senn, 2004).
3.3
E-MAIL OR ELECTRONIC MAIL
This is the transmission of electronic messages over the Internet. People all over the world
can now send e-mail containing text, graphics, pictures and different types of file
attachments. You need the following to send and receive e-mail; e-mail account, access to the
Internet, and an e-mail program. The most widely use e-mail programs are Outlook Express
and Microsoft office outlook, others are located on the company’s Web site like yahoo,
google, hotmail,e.t.c. A typical e-mail message has three basic elements: header, message and
signature.
The Header appears first and include the following information:
• Addresses: addresses of the person sending, receiving, and, optionally anyone who is
to receive copies. E-mail addresses have basically three main parts: the user’s name,
the domain name and the domain code. For example [email protected], the
user’s name is dr_ahmed . The server providing services for Dr Ahmed is noun. The
domain code indicates that the provider is an educational institution in Nigeria.
• Subject: A one line statement used to present the topic of the message. It also appears
when a person checks his/her mail box.
• Attachment: these are documents, photos or worksheets attached and send together
with the typed text in a mail. The file name usually appears on the attachment line if a
message contains an attachment.
179
The Message: this is the short note written in text format and usually straight to the point.
The Signature: the signature line provides additional information about the sender: name,
address, and telephone number.
The draw back to this technology is the presence of Spam (unwanted and unsolicited mails)
and Computer Viruses (destructive programs attached to Spam).
Figure 16.5 Showing sample E-mail.
Source: (O’Leary, 2004).
3.4
BROWSING THE WORLD WIDE WEB
Browsers are programs that provide access to Web resources. This software connects you to
remote computers, open and transfers files, display text and images, and provides in one tool
an uncomplicated interface to the Internet and Web documents. Some basic browsing terms
include;
180
•
Surf: this is the process of exploring the Web, by easily moving form one Web site to
another using browser like Netscape Navigator, Microsoft Internet Explorer, Mozilla
and Opera.
•
Uniform Resource Locators (URLs): for browsers to connect to resources, the
location or addresses of the resources must be specified. These addresses are called
URLs. The first part presents the protocols (http://) used to connect to the resources
while the second part presents the domain name (noun). The last part of the domain
name following the dot (.) is the domain code (edu, ng).
The URL http:// www.noun.edu. ng connects your computer to a computer that
provides information about the National Open University of Nigeria, which is an
educational institution located in Nigeria.
•
Protocol (http://): these are rules for exchanging data between computers. The
Protocol (http://) are the most widely used Web protocol.
•
Domain Name and Domain Code: the domain name is the name of the server where
the resource is located on the URL. Many URLs have additional parts specifying
directory paths, file names, and pointers. The domain code identifies the type of
organization. For example;
.com commercial organization
.edu educational institution
.ng
Nigeria(.jp-Japan, .uk-United kingdom, .zo-South Africa, .gh- Ghana)
.org Organisation
.gov government of a nation
•
Hyperlinks or Links: when the browser connects to the Internet it opens up the Web
page specified in the browser settings containing information about the site.
Hyperlinks are the references that connect to other documents containing related
information like text files, graphic images, audio, and video clips on a Web page.
•
Web Server: this is the computer that stores and shares document to nearby computer
systems around the world. When a link is established with the Web Server the
document is automatically displayed on your screen.
•
Applets: are links to special programs on a Web page, they are written in Java
programming Language. Java applets are widely used to add interest and activities to
a Web site by presenting animations, displaying graphics, providing interactive
games, and much more.
181
One Home Page, Many Links
•
Home Page: The first page of a Web site, which identifies the site and provides
information about the contents of electronic documents that are part of the site.
Creating Web Pages Using HTML
•
Hypertext Markup Language (HTML): A set of commands that specifies the
position, size, and color of text, the location of graphic information, and the
incorporation of sound and video. HTML commands also identify the words or
images that will serve as hyperlinks to other documents.
Browser Software
•
Web Browser: Client computer program designed to locate and display information
on the World Wide Web.
•
Graphical Browser: A type of browser used with the Web that displays both text and
images within a page.
•
–
Title Bar
–
Menu Bar
–
Net Site
–
Toolbar
–
In-line Image
–
Hyperlinks
–
Status Bar
–
Activity Indicator
–
Scroll Bars
Navigating the Web
–
Using Search Engines
–
Directories
182
3.5
WEB UTILITIES
These are specialized utility programs that make using the internet and the Web easier and
safer, some of these utilities are internet services for connecting and sharing resources over
the Internet. Others are browser programs that either become part of your browser or are
executed from your browser.
• Telnet
Telnet is an Internet standard that helps you connect to another computer remotely on the
Internet and use that computer as if you were a terminal in the next room. You do that
using the computer’s IP address, for example Telnet 192.168.1.30, then you enter the
computer’s security code (Username and Password).
• FTP
FTP is an acronym for File Transfer Protocol which is an Internet standard for
transferring files. Downloading is the process of receiving a file from another computer
while Uploading is the process of sending a file to another computer.
• Plug-ins
Plug-ins are automatically located and operated as part of a browser. Many Web sites
require specific plug-ins to fully express their content. Some plug-ins are included in
many of today’s browsers while others must be installed.
– Quick time player from Apple-for playing audio and video files
– Windows Media player from Microsoft-for playing audio and video files and
much more as discussed earlier.
– Cosmos form Silicon Graphics-for displaying three dimensional graphics.
– Adobe Reader from Adobe-for viewing and printing a variety of standard
forms and other documents saved in a special format called PDF.
• Filters
Filters are used by parents or organizations to block certain sites and to monitor use of the
Internet and the Web. Filters are special programs used to generate reports detailing the
total time spent on the Internet and the time spent on individual Web sites, chat groups,
and news group. There are basically three well known filters: Cyberpatrol, Cybersitter,
and NetNanny.
4.0
CONCLUSION
Understanding how to efficiently and effectively use the internet to browse the web,
communicate with others, and locate information are indispensable ICT competencies.
183
5.0
SUMMARY
You learnt in this unit that:
• The web also known as the World Wide Web (WWW) provides a multimedia
interface to recourses available on the internet.
• Web sites are group of related pages and Web portals are designed to encourage you
to visit them each time you are on the Web, to act as your home base, and to use as a
gateway to their resources.
• Web utilities are specialized utility programs that make using the internet and the
Web easier and safer
•
6.0
Browsers are programs designed to locate and display information on the World Wide
Web by displaying both text and images within the page.
TUTOR MARKED ASSIGNMENT (TMA)
a. When was the WWW launched and where?
b. Explain the elements of a URL and the purpose of each.
c. What do you understand by the terms downloading and uploading?
d. What are the three basic elements of an e-mail message?
7.0
FURTHER READING/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
184
MODULE 3
UNIT 17
DISTRIBUTED NETWORKS AND THE INTERNET
ELECTRONIC COMMERCE AND ELECTRONIC BUSINESS
1.0
Introduction................................................................................................................174
2.0
Objectives...................................................................................................................174
3.0
Main Content…………………………......................................................................174
3.1
Players in the Game.......................................................................................174
3.2
Types of E-Commerce…................................................................................174
3.3
Benefits of E-Commerce................................................................................176
3.4
Mode of Payment in E-Commerce.................................................................176
4.0
Conclusion….........................................…................................................................177
5.0
Summary….........................................…...................................................................177
6.0
Tutor Marked Assignment..........................................................................................177
7.0
Further Readings/References….................................................................................177
185
1.0
INTRODUCTION
In Unit 16, you learnt that the Internet came with a lot of opportunities, especially its ease of
access and use. Understanding how the Internet and the Web work to provide a foundation
for e-commerce is an enormous potential. In this unit you will learn how to trade over the
Internet through Electronic Commerce.
2.0
OBJECTIVES
After you have read this unit, you should be able to know:
• Concept of E-Commerce
• The advantages and disadvantages of E-commerce
• Types of E-commerce
3.0
MAIN CONTENT
Electronic commerce, also known as e-commerce is the buying and selling of goods over the
Internet. Shopping on the Internet is growing rapidly because E-commerce provides
incentives for both buyers and sellers.
3.1
PLAYERS IN THE GAME
There are two major parties in the e-commerce business world. They are:
– Buyers
– Sellers.
Buyer
From the buyer’s perspective, goods and services can be purchased at any time of the day or
night. Traditional commerce, also known as bricks and mortar business, is typically limited to
standard business hours when the seller is open. Buyers don’t have to travel physically to the
seller’s location. Busy parents don’t have to arrange for a nanny or baby sitter in order to visit
the market or go for shopping.
Seller
From the sellers perspective the cost associated with renting a shop is eliminated. For
example a supermarket can operate on the Web without a physical store or employing a lot of
sales staff. Traditional stores maintain an inventory of goods in their stores and periodically
replenish this inventory from warehouses. With e-commerce, there is no in-store inventory
and products are shipped directly from warehouse.
3.2
TYPES OF E-COMMERCE
There are three basic types of electronic commerce: business-to-consumer (B2C), consumerto-consumer (C2C), business-to-business (B2B).
A.
Business-to-consumer (B2C)
B2C e-commerce is the fastest growing type of e-commerce. It is used by large corporation,
small corporations and start-up corporations. This involves the sale of a product or service to
the general public or end-users. Most times this arrangement eliminates the middleman by
186
allowing the manufacturers to sell directly to customers. Existing retailers use B2C ecommerce to create a presence on the Web as a means of reaching out to customers. Because
extensive investments are not required to create traditional retail outlets and to maintain large
marketing and sales staff, e-commerce allows start-up companies to compete with larger
established firms.
The three most widely used B2C applications are online banking, financial trading, and
shopping.
– Online banking: this is known as e-banking, a standard feature for banking
institution. Customers are able to go online with a standard browser to perform many
banking operations. These online operations include accessing account information,
balancing check books, transferring funds, paying bills, re-charging mobile phones,
and applying for loans. Using these electronic services is safer than using Automated
Teller Machine (ATM).
– Financial trading: this is referred to as online stock trading or e-trading. it allows
investors to research, buy, and sell stocks and bonds over the Internet. The greatest
advantage of using e-trading compared to a traditional broker is cost. Traditional
brokers provide advice based on their research. E-trading sites typically provide
research on individual stocks that many e-traders use to make their trading decisions.
– Shopping: this is referred to as e-retailing or e-tailing, it includes the buying and
selling of wide range of consumer goods over the Internet. The greatest e-retailing
success have been in books, travel, music, and health industries. Web storefronts are
virtual stores that allow shoppers to visit, inspect merchandise, and make purchases
on the Web. A new program called Web storefront creation packages or commerce
servers has recently evolved to help business create virtual stores, that allow visitors
to register, browse, place products into virtual shopping charts, and trade through a
safe communication.
B.
Consumer-to-consumer (C2C)
This trading involves individuals selling to individuals, and takes the form of an electronic
classified advert or an auction (Web Auction). Goods are describe and interested buyers
contact sellers to negotiate prices, and buyers and sellers never meet face-to-face. Sellers post
descript ion of products at a Web site and buyers submit bids electronically. There are two
basic types of Web auction sites.
– Auction house sites: they sell a wide range of merchandise directly to bidders. The
auction house owners present merchandise that is typically from a company’s surplus
stock. They are usually considered safe to shop.
– Person-to-person auction sites: they operate more like flea markets. The owner of the
site provides a forum for numerous buyers and sellers to gather. While the owners
facilitate the building process, they are not involved in completing transactions or in
verifying the authenticity of the goods sold. As with purchases at a flea market,
buyers and sellers need to be cautious.
187
C. Business-to-business (B2B)
B2B involves the sale of a service or product from one business to another. This is typically a
manufacturer’s supplier relationship. For example, a furniture manufacturer requiring raw
materials such as wood, paint, and varnish. In B2B e-commerce manufacturers place an order
electronically with suppliers and many times payment is made electronically. The most
popular B2B e-commerce is for automobile parts, electronics including computers and health
care.
3.3
•
BENEFITS OF E-COMMERCE
Geographic Reach: geographical distance does not create a barrier to reaching and
serving customers electronically or for interacting with suppliers.
•
Speed: near instant exchange of information means the interaction between buyer and
seller takes place at rapid speed.
•
Productivity: individuals are more productive when they can do more work in a
segment of time. Spending less time getting information means more time available
for its use, therein producing greater efficiency.
•
Information Sharing: virtually any form of information- text, graphics, audio, video
or animation- can be transmitted to recipients location on the network.
•
New Features: new features can be added to product and services offered over
communications network, including personalized, automatic notification of activities
and instant delivery.
•
Lower Costs: the cost of business is reduced when companies and individuals can be
reached quickly and without respect to geographical distance, while improved
efficiencies results form electronic information exchange.
•
Competitive Advantage: those companies that develop and implement an effective
electronic commerce strategy have business advantages over others in their industry
that can not over similar products, services, or operating capability.
3.4
MODE OF PAYMENT IN E-COMMERCE
The single greatest challenge for e-commerce is the development of fast, secure, and reliable
payment method for purchased goods. The three basic payment options are check, credit card,
and electronic cash.
• Check: these are the most traditional and perhaps the safest. Unfortunately, check
purchases require the longest time to complete. After selecting an item, the buyer
sends a check through the mail. Upon receipt of the check, the seller verifies that the
check is good. If it is good, then the purchased item is sent out.
• Credit card: with credit cards purchases are faster and more convenient than check
purchases. Credit card fraud however is a major concern for both buyers and sellers.
Criminals known as carders specialize in stealing, trading, and using stolen credit
cards over the Internet.
188
•
Electronic cash: this also refers to e-cash or cybercash or digital cash, is the internet
equivalent to traditional cash. Buyers purchase e-cash from a third party (a bank that
specializes in electronic currency) by transferring funds from their banks. Buyers
purchase goods using e-cash while sellers convert the e-cash to traditional currency
through the third party. Although not as convenient as credit card purchases, e-cash is
more secure. A list of e-cash providers are: Ecash www.ecash.com, EmoneyMail
www.emoneymail.com, Internet Cash www.internetcash.com, and PayPal
www.paypal.com.
4.0
CONCLUSION
We should note that while there are numerous advantages to e-commerce, there are
disadvantages as well, and just like any other type of commerce, e-commerce involves two
parties: businesses and consumers.
Some of these disadvantages include the inability to provide immediate delivery to goods, the
inability to sample goods before purchasing, and the issues relating to security of online
payment.
5.0
SUMMARY
In this unit we learnt that:
• There are three types of e-commerce namely: business-to-consumer (B2C), consumerto-consumer (C2C), business-to-business (B2B).
• With e-commerce, there is no in-store inventory and products are shipped directly
from warehouse.
• Electronic Commerce (e-commerce)is the use of communication networks, including
the public Internet, to conduct commercial transactions between businesses or with
consumers.
6.0
a.
b.
c.
d.
7.0
TUTOR MARKED ASSIGNMENT
What are the three types of e-commerce?
What are the three basic payments for electronic payments?
What is the greatest challenge for e-commerce development?
Among the three types of e-commerce, which is the fastest growing business?
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
189
MODULE 3
UNIT 18
DISTRIBUTED NETWORKS AND THE INTERNET
LAUNCHING INFORMATION TECHNOLOGY APPLICATIONS
PROJECTS
1.0
Introduction................................................................................................................179
2.0
Objectives...................................................................................................................179
3.0
Main Content .............................................................................................................179
3.1
3.01
Information Technology Applications...............................................179
3.02
Characteristics of Personal and Enterprise System............................179
3.03
Impact of ICT Applications...............................................................180
Enterprise Systems Project.............................................................................180
3.1.1 Project Proposal.................................................................................180
3.2
Information and Communication Technology Department.......................................181
3.3
System Analyst...........................................................................................................183
3.4
Systems Analysis and Design.....................................................................................184
4.0
Conclusion..................................................................................................................189
5.0
Summary…................................................................................................................189
6.0
Tutor Marked Assignment………………….............................................................189
7.0
Further Readings/References….................................................................................190
190
1.0
INTRODUCTION
In Unit 13 and 14 you learnt about the personal and enterprise communication networks. In
this unit you will learn about the origin of IT applications in business and understand why
they have become so prominent.
2.0
OBJECTIVES
After you have read this unit, you should be able to know:
•
•
•
•
The Characteristics of ICT Applications Project
The Key player in ICT Projects
The ICT Department
Information System Analysis and Design
3.0
MAIN CONTENT
3.01 INFORMATION TECHNOLOGY APPLICATIONS
There are basically two categories of IT applications, they are:
• Single-user System/Personal System: An IT system used by only one person. A
system that stands alone and is not interconnected with other companies or shared by
other people.
• Enterprise System: Usually involves the same types of components as a personal
system, plus server or mainframe, database, and network. It is generally a shared
system.
3.02
CHARACTERISTICS OF PERSONAL AND ENTERPRISE SYSTEM
Table 18.1
Characteristics of Personal and Enterprise System
S/No.
Characteristics
Personal System Enterprise System
X
X
1
Designed for Hands-On Usage
2
3
Hands-on System: A system in which a
user enters data and information, directs
processing, and determines the types of
output to be generated.
Used to Improve Personal Performance
Tailored to Personal Preferences and
Performance
X
X
X
X
4
Designed for Shared Use
X
5
Designed for Sharing Data Resources
X
6
Designed to Connect a Variety of Users
X
X
7
Designed for Larger Size and Scope
Source: (Senn, 2004).
191
3.03
•
IMPACT OF IT APPLICATIONS
Improved Productivity
– Productivity: The relationship between the results of an activity (output) and
the resources used to create those results (inputs).
Table 18.2
Showing relationship between an activity and resources in Productivity
Inputs
Outputs
Hours of work required to complete a task Length of time to complete report and
number of projects produced
Equipment Investment
Number of contracts negotiated
Total Project budget
Amount of profit per complete contract
Source: (Senn, 2004).
– Personal Productivity Software: Software packages that permit activities to
be completed more quickly, allow more activities to be completed in a
particular period of time, or allow a task to be completed with fewer resources.
•
Greater Effectiveness
– Effectiveness: The extent to which desirable results are achieved.
•
Increased Creativity and Innovation
3.1
ENTERPRISE SYSTEMS PROJECT
These are projects designed for organizations to promote efficient and safe use of data across
the networks within their organizations.
• Systems Development: The process of examining a business situation, designing a
system solution to improve that situation, and acquiring the human, financial, and
information technology resources needed to develop and implement the solut ion.
• Project Management: The process of planning, organizing, integrating, and
overseeing the development of an IT application to ensure that the project’s objectives
are achieved and the system is implemented according to expectations(as will be
discussed in details in the next module, Unit 20.)
3.1.1 PROJECT PROPOSAL
•
Project Proposal: A proposal for a systems project prepared by users or systems
analysts and submitted to a steering committee for approval.
•
Steering Committee Review
– Steering Committee: A group of people from various functional areas of a
business that determines whether a systems development project proposal is
desirable and should be pursued.
192
3.2
INFORMATION AND COMMUNICATION TECHNOLOGY DEPARTMENT
In the design of our organizational chart, the Chief Executive Officer (CEO) is the overall
highest ranking staff of the organization. The Chief Information Officer (CIO) is also the
highest ranking information officer and he reports to the CEO. Information services are
placed at the same level of importance as the traditional business functions (e.g., Finance,
human Resources, Sales and Marketing, Production and so on). The rest of information
services are organized according to the following functions or centers:
a. System development: Most system analyst and programmers work for the systems
development group in the information services group or department of a business.
Alternatively systems analyst (under different titles) works for IT consulting firms,
outsourcers, and application software vendors.
The Center for Excellence is a group of experts who establish and enforces methods,
tools, techniques, and quality for all system development projects. Experienced
analyst, system designer, system builders staff the center. They provide consulting
and mentoring services for all projects.
b. Data administrator: this center manages the data and information resources in the
organization. This includes the database that are (will be) used by system developers
to support application. Data administrators usually employ several system analysts
known as data analyst who analyses database requirements and design and construct
the corresponding databases.
c. Telecommunications: this center design, constructs, and manages the computer
networks that have become essential to most businesses. The network analyst does the
network design.
d. End-user computing: this center supports the growing base of personal computers
and local area networks in the end-user community. It provides system support;
installation services, training, and help-desk services.
e. Computer Operations: this center runs all of the shared computers including
mainframes, minicomputers, and non-departmental services. This unit rarely employs
system analyst.
193
Chief Executive Officer Other Corporate Chief Information Officer Director, Computer Operations Director, Departmental Computing Director, Systems Development Director, Data Director, Telecommunications Corporate Administrator Webmasters Manager, Computer Operations Departmental Analyst Project Database Managers Administrator Network Engineers Senior Data Network Analysts Analyst Administrator End User Trainee Analyst / Database Designers Network Technician Shift Supervisor Manager, End User Computing Capacity Analyst Programmers Computer Operators End User Consultant Manager, Development Centre Manager, Centre of Excellence Development Consultant Figure 18.1
THE ORGANISATIONAL CHART OF AN INFORMATION AND
COMMUNICATION TECHNOLOGY (ICT) DEPARTMENT.
Source: (Whitten, 2001).
194
Local Area Network Administrator 3.3
SYSTEM ANALYST
The System Analyst is the key player in most IT application projects, because the System
Analyst follows the steps described in the system life cycle (as will be explained in the next
topic). Analyst plan and design new systems or reorganize a company’s computer resources
to best utilize them. Analyst follow the systems development life cycle through all steps:
preliminary investigation, analysis, design, development, implementation, and maintenance.
• Professional Skills
– Problem Solving
– Outcome Thinking
– Creativity
– Meeting Skills
– Communication Skills
The System Analyst is the IT professional responsible for working with users to determine a
system’s requirements and for describing the features needed in the system. Systems Analyst
position usually requires a bachelors degree in computer science and technical experience in
the following fields listed bellow because he or she will have to interact with experts dur ing
the project processes.
– System Design: the technical work of designing the system and its software.
– Programming/Analysis: determining system requirements and developing and
implementing the systems.
– Web Development: additional capabilities that enable him or her to use
expertise in creating IT applications that will involve the Internet or company
intranets and extranets, Web browsers, and the display of information using
browsers.
– Computer Security: techniques developed to safeguard information and
information systems stored on computers.
– Software Engineering: the writing of instructions for a computer to use to
manipulate data, such as a word-processing program or a video game.
– Database Administration: any collection of data organized for storage in a
computer memory and designed for easy access by authorized users.
– Computer Hardware Engineering: the study of the equipments involved in
the function of a computer.
– Networking: is a system used to link two or more computers. Network users
are able to share files, printers, and other resources; send electronic messages;
and run programs on other computers. 195
3.4
SYSTEMS ANALYSIS AND DESIGN
A system is a collection of activities and elements organized to accomplish a goal. System
analysts are computer professionals that typically conduct system analysis and design.
System analysis and design is a phased problem solving procedure that make up the system
life cycle. The Systems Development Life Cycle (SDLC) is a six-phased set of activities that
brings about a new IT application.
The phases are:
• Problem Recognition/Preliminary Investigation: indentifies problems or needs.
• System Analysis/Requirements Determination: studies present system and specify new
requirements.
• Systems Design: design new or alternate system to meet new requirements.
• System Development and Construction: acquiring, developing and testing needed
hardware and software.
• Systems Implementation: installing new system and training people.
• System Maintenance/Evaluation and Continuing Evolution: periodically evaluating
and updating system as needed.
Phase 1. Preliminary Investigation Phase 2. Phase 5. System Analysis Systems Maintenance System Life Cycle Phase 5. Phase 3. Systems Implementation System Design Phase 4. Systems Development Figure 18.2
System Life Cycle.
Source: (O’Leary, 2004)
196
Phase 1:
Problem Recognition/Preliminary Investigation
The preliminary investigation determines the need for a new IT application project. It is
typically requested by an end-user or a manager. Three task of this phase are defining the
problem, suggesting alternative systems, and preparing a report.
• Defining the Problem: the current Information system is examined to determine who
needs what information, when the information is needed and why. If the existing
information system is large, then a system analyst conducts the survey. Otherwise the
end-user conducts the survey.
•
Suggesting Alternative Systems: some possible alternative systems are suggested.
Based on interviews and observations made in defining the problem, alternative
information systems are identified.
•
Preparing a short report: to document and communicated the findings of Phase ,
preliminary investigation, a short report, alternative information systems are
identified.
Note that the merits and feasibility of a project proposal are determined in this phase.
• Three types of feasibility
– Operational
– Financial/Economic
– Technical
Problem Phase 1. Alternatives Analysis Preliminary Investigation Report Figure 18.3
Preliminary Investigation
Source: (O’Leary, 2004)
Phase 2:
System Analysis/Requirements Determination
In system analysis data is collected about the current system. The focus is on determining the
requirements for a new system, three task of this phase are gathering data, analyzing data, and
documenting the analysis.
197
•
Gathering data: data is gathered by observations, interviews, questionnaires, and
looking at documents. One helpful document is the organizational chat, which shows
a company’s function and level of management.
•
Analyzing the Data: there are several tools for the analysis of data, including
checklist, top-down analysis, grid chats, decision tables, and system flow chats.
•
Documenting system Analysis: to document and communicate the findings and
phase 2, a systems analysis report is prepared for higher management.
Gather Phase 2. Analyse Design System Analysis Report Figure 18.4
System Analysis
Source: (O’Leary, 2004)
Phase 3:
Systems Design
In the system design phase, a new or alternative information system is designed. This phase
consists of three tasks:
• Designing Alternative Systems: alternative information systems are designed. Each
alternative are evaluated for:
– Economic feasibility: cost versus benefit: time for system to pay for itself.
– Technical feasibility: had ware and software reliability.
– Operational feasibility: System work within organisation
•
–
–
–
–
•
Selecting the best system: There are four questions considered when selecting the
best system
Will the system fit into an overall system?
Will the system be f flexible enough to be modified as needed in the future?
Will it be secured against unauthorized used?
Will the system benefits exceed its costs?
Writing the system Report: To document and communicate the findings of Phase, a
system design report is prepared for higher management.
198
Alternatives Development Phase 3. Best Systems Design Report Figure 18.5
System Design
Source: (O’Leary, 2004)
Phase 4:
System Development and Construction
In the systems development phase, software and hardware are acquired and tested.
• Acquiring Software: two ways to acquire software are:
– Purchase: buy off the shelf packaged software to be modified if necessary.
– Custom designed: create programs following programming steps.
• Acquiring Hardware: is very critical and involves consideration for future company
growth, existing networks, communication capabilities, and training.
• Testing the New System: using sample data, the new system is tested. This step can
take several months for a complex system.
Software Phase 4 Hardware Implementation Systems Development Test Figure 18.6
System Development
Source: (O’Leary, 2004)
199
Phase 5:
Systems Implementation
This is the process of changing to the new system and training people.
• Types of Conversion
Four ways to convert a system are:
– Direct approach: abandoning the old and starting up the new system; can be very
risky and not recommended.
– Parallel Approach: operating the old and the new side by side until the new one
proves it worth; low risk but expensive.
– Pilot Approach: trying out the new system in only one part of an organization.
Compare to parallel, pilot is riskier and less expensive.
– Phased Approach: implementing the new system gradually; low risk but expensive.
•
Training: a software trainer may be used to train end-users in the new system.
Conversion Type Maintenance Phase 5 Systems Implementation Train Figure 18.7
System Implementation
Source: (O’Leary, 2004)
Phase 6:
System Maintenance/Evaluation and Continuing Evolution
This is the final phase. It consist of several audit followed by periodic evaluation.
• System Audit: once the system is operational, the systems analyst performs a system
audit by comparing the new system to its original design specifications. If the system
does not meet these specifications, some further redesign of the system may be
required.
•
Periodic Evaluation: the new system is periodically evaluated to ensure that it is
operating efficiently. If it is not, some redesign may be required.
200
System Audit Investigation Phase 6 Systems Maintenance Periodic Evaluation Figure 18.8
System Maintenance
Source: (O’Leary, 2004)
Note:
Due to time pressures, it is not always feasible to follow every phase of the traditional system
life cycle. Other alternatives that can be used will be found in the referenced books, which
require less time and cost less.
4.0
CONCLUSION
In conclusion, the ICT projects need careful planning before being launched. This is essential
because if it is not properly analysed and designed, the application project will not meet the
end-user’s requirements.
5.0
SUMMARY
In this unit you learnt about:
• the distinguishing characteristics of an IT application
• the benefits of IT applications to users and enterprise
• the six phases of the systems development life cycle
6.0
TUTOR MARKED ASSIGNMENT
a. What are ICT applications?
b. What are enterprise systems projects?
c. Who is the most valuable player in ICT application projects and what are his
competent skills?
d. What is feasibility and whose responsibility is it in the IT department?
201
7.0
•
FURTHER READINGS/REFERENCES
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
Paul F., James M. and Peter H. (2004), System Development Life Cycle Models and
Methodology: System Analysis and Database development. New Jersey, US:
Pearson Prentice Hall.
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
•
Whitten, L. W., Bentley, L. D., Dittman, K. C. (2001). System Analysis and Design
Methods (5th Edition). New York, US: McGraw-Hill.
202
MODULE 4
UNIT 19
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
CREATING ENTERPRISE APPLICATIONS
1.0
Introduction................................................................................................................192
2.0
Objectives...................................................................................................................192
3.0
Main Content..............................................................................................................192
3.1
Developing Open Shared Systems.................................................................192
3.1.1 Development Alternatives..................................................................192
3.1.2 Open Systems for Sharing…..............................................................192
3.1.3 Shifting Development.........................................................................192
3.1.4 Building IT with Components…........................................................193
3.2
System Analyst’s Tools and Techniques........................................................193
3.2.1 Data Collection Techniques…...........................................................193
3.2.2 Data Processing Tools........................................................................194
3.3
Computed-Aided Systems Engineering (CASE) …......................................196
3.4
Unified Modeling Language (UML) ….........................................................197
4.0
Conclusion..................................................................................................................199
5.0
Summary….............................................…...............................................................199
6.0
Tutor Marked Assignment.........................................................................................200
7.0
Further Readings/References….................................................................................200
203
1.0
INTRODUCTION
The Unit 18, you learnt about the origin of IT projects in business and how they are launched.
This unit will introduce you to how the projects are manage and accessed within the
enterprise level and the tools the system analyst use in developing an open shared system.
2.0
OBJECTIVES
After you have read this unit, you should be able to:
• Identify the characteristics of shared systems.
• Describe the tools and techniques available to system analysts for collecting data and
developing IT applications.
• Summarize the purpose and characteristics of unified modeling language (UML).
• Identify the use of a CASE tool
3.0
MAIN CONTENT
3.1
DEVELOPING OPEN SHARED SYSTEMS
In an enterprise system, two or more users share computers, communication technology, and
applications. The introduction of an enterprise system into an oeganisation affects everyone
who interacts with the application or receives information generated by the system. For this
reason enterprise systems are not developed by individual staff members, but rather by the
organizations information group known as the Management Information System (MIS)
department.
3.1.1 DEVELOPMENT ALTERNATIVES
The information technology group can take any of the three approaches to developing an
application:
• Build the application itself.
• Purchase a prewritten application.
• Contract out the application development.
3.1.2 OPEN SYSTEMS FOR SHARING
•
•
Open System: A software system that runs on different computer and
communications hardware.
Interoperability: The perfect exchange of data and information in all forms (data,
text, sound, and image, including animation) between the individual components of an
application (hardware, software, and network).
3.1.3 SHIFTING DEVELOPMENT
•
•
•
Craft Approach
Assembly Approach
Object: A component that contains data about itself and how it is to be processed.
204
3.1.4 BUILDING IT WITH COMPONENTS
Figure 19.1 Object Design Tools and Option tool.
Source: (Senn, 2004).
3.2
SYSTEM ANALYST’S TOOLS AND TECHNIQUES
3.2.1 DATA COLLECTION TECHNIQUES
This is the process of collecting data relating to business transactions for processing by any
appropriate means. This could be performed through the following methods:
•
Interviews
– Structured Interview: An interview in which the questions are prepared in
advance and each interviewee is asked the same set of questions.
– Unstructured Interview: An interview in which the questions may be prepared
in advance, but follow-up questions vary, depending on the interviewees’
background and answer.
205
•
Questionnaire: A sheet of questions used to collect facts and opinions from a group
of people.
•
Document Examination/Record Inspection: The review of company documents
about a system or opportunity under investigation.
•
Observation: The process of watching an activity takes place to collect information
about that activity.
•
Sampling: The process of collecting data and information at prescribed intervals.
3.2.2 DATA PROCESSING TOOLS
•
System Flowcharts: A graphical description of a business process or procedure using
standard symbols to show decision logic.
Figure 19.2 Symbols used in system Flowcharts.
Source: (Senn, 2004).
•
Dataflow Diagram (DFD): A chart showing the movement of data through a system.
– DFD Levels
• Leveling: The process of exploding processes in a dataflow diagram to
show more detail.
206
Figure 19.3 Symbols used in Dataflow Diagrams.
Source: (Senn, 2004).
Figure 19.4 Dataflow Diagram for Order and Invoice Handling at a Mail-Order Company.
Source: (Senn, 2004).
•
Data Dictionary/Repository: A catalog that lists and describes all the types of data
flowing through a system. Composed of data elements and a data structure.
•
Data Element: The component of a data dictionary that includes data names, alternate
names, and length allowances.
207
•
3.3
Data Structure: The set of data elements used together and the name that collectively
identifies the set.
COMPUTED-AIDED SYSTEMS ENGINEERING (CASE)
Computed-Aided Systems Engineering/Computer-Aided Software Engineering (CASE)is a set
of tools used in systems development to improve the consistency and quality of the system
while automating many of the most tedious and time-consuming systems tasks.
–
–
–
–
–
Charting and Diagramming Tools
Centralized Information Repository
Interface Generators
Code Generators
Project Management Tools
Figure 19.5 CASE Tools Diagrams.
Source: (Senn, 2004).
•
Front-End CASE Tool: A CASE tool that automates the early (front-end) activities
in systems development.
•
Back-End CASE Tool: A CASE tool that automates the later (back-end) activities in
systems development.
•
Integrated CASE (I-CASE) Tool: A CASE tool that spans activities throughout the
entire systems development life cycle.
208
Figure 19.6 Types of CASE Tools.
Source: (Senn, 2004).
3.4
•
UNIFIED MODELING LANGUAGE (UML)
Unified Modeling Language (UML) is a standard method/technique for visualizing,
describing, and documenting the details of an IT application. It is being used more
extensively in industries to assist in systems analysis.
•
Actor: Anyone or anything that will interact with the application.
•
Activity Diagram: Shows the flow of control in an application.
Figure 19.7 Actors in Mail Order Use CASE.
Source: (Senn, 2004).
•
Use Case Diagram: Provides context for the system, illustrating the actors, the use
cases, and the flow or interaction between use cases and actors.
– Use Case: Identifies the sequence of activities performed for an actor.
•
Use Case Description: Describes the use case in ordinary language, including its
identifying name and actors.
209
Figure 19.8 Use CASE Description.
Source: (Senn, 2004).
•
Class Diagram: Describes an object class, including the class name, attributes, and
methods.
•
Other UML Diagrams
– Sequence Diagram
– State Transition Diagram
– Component Diagram
210
Figure 19.9 Class Descriptions for Customer and Order Objects.
Source: (Senn, 2004).
4.0
CONCLUSION
When creating an enterprise application, it is the responsibilities of the System Analyst to use
the required tools and techniques to make the software system to perform on different
computer and communications hardware.
5.0
SUMMARY
In this unit we learnt that the System Analyst use the following tools and techniques to make
an IT application accessible to end users in an organistaion.
•
Techniques
–
•
Interviews, Questionnaire, Document Examination/Record Inspection,
Observation, Sampling and Dataflow Diagram (DFD)
Tools
–
Computed-Aided Systems Engineering/Computer-Aided Software Engineering
(CASE)
–
Unified Modelling Language (UML)
211
6.0
TUTOR MARKED ASSIGNMENT
a. In a DFD chart what does the arrow stand for?
b. What are the data collection techniques the System Analyst use.
c. State the two basic tools the System analyst used when creating an ICT project.
d. What are the two types of interview conducted by a System Analyst during analysis?
7.0
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
212
MODULE 4
UNIT 20
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
PROJECT MANAGEMENT
1.0
Introduction................................................................................................................202
2.0
Objectives ..................................................................................................................202
3.0
Main Content..............................................................................................................202
3.1
Managing A Project.......................................................................................203
3.1.1 Stages of A Project and How To Complete Them………………...203
4.0
Conclusion..................................................................................................................206
5.0
Summary....................................................................................................................206
6.0
Tutor Marked Assignments........................................................................................207
7.0
Further Readings/References….................................................................................207
213
1.0
INTRODUCTION
In Unit 19 you learnt about the tools used to make an ICT application available for end-users
for easy sharing of resources. This unit will introduce you to the process involved in
managing an IT project, from starting to completion.
2.0
OBJECTIVES
After this unit, you should be able to:
• Break a complex project into manageable sub-projects
• Assign responsibility/ownership of project components
• Set reasonable milestone's for the completion of major tasks
• Develop and complete a project plan
3.0
MAIN CONTENT
Project management is the art of matching a project's goals, tasks, and resources to
accomplish a goal. To accomplish a goal one need limited time, money, and resources
(human and machinery). One can think of a project as a process that involves inputs and
outputs. Successful projects require doing the right things, with the right tools, and in the
right way.
INPUTS •
Goals •
Team Staff •
.N •
Time •
Equipment OUTPUTS PROJECTS Figure 20.1 Simple Project Management System.
Source: (MITOPENCOURSEWARE, 2008)
214
•
Deliverables 3.1
MANAGING A PROJECT
3.1.1 STAGES OF A PROJECT AND HOW TO COMPLETE THEM
Stage 1: Defining the goals of the project:
Starting a project with the correct goal(s), make it easy to accomplish the goal(s). This must
be a team activity to ensure that everyone is given the opportunity to contribute and "buy-in"
to what is going to happen. At the end of this stage, every team member should have an
understanding of what must be accomplished.
This part of the project should end with a document that lists the goals with a short statement
providing some detail about the success rate and a vital few requirements that define the
goal(s) to be accomplished. It also prevents teams from performing unnecessary iteration and
improvement on a goal(s) which has been sufficiently accomplished.
Stage 2: Define project tasks/activities:
Each goal or sub-set of goals should be matched to the tasks required to accomplish them.
This is best done by listing the goals on the left side of a sheet of paper, then writing the tasks
to their right. The group should agree that the specify task will accomplish the goals as per
required in the definitions for success the team laid out in the previous stage.
Stage 3: Determine and verify resource requirements:
Resources are those things which are needed to accomplish the project goals. Resources may
include, but are not limited to:
–
–
–
–
–
–
People
Time
Money
Space
Computers
Software, e.t.c.
The most important component of determining resource requirements is to be realistic. One
of the most common mistakes project managers make is to underestimate the amount and
type of resources required. This leads to projects that run over budget and fall behind
schedule. DO NOT attempt to do any of the following:
–
–
–
Squeeze a project into a shorter time frame to please your boss
Cut corners to minimize resource requirements
Plan on a best-case basis, i.e. "If everything goes correctly, we will finish on time."
215
Determine what you need to get the job done correctly, on time, and on budget. It is not a bad
idea to build in a safety margin here. This is often referred to as "padding". For instance, one
might multiply the estimated time to complete a task/project by say 20% to allow for
additional time to deal with unexpected occurrences. The amount of padding usually depends
on the certainty one has as to how effectively the resources can be used. One should keep
padding to a minimum.
Once the requirements have been set, it is important to verify that the team will have access
to them.
Stage 4: Identify risks and develop mitigation (backup) plans:
Projects always involve a finite amount of uncertainty (risk) that may lead to problems and
surprises during the project. Dealing with surprises requires more time, energy, and money
than originally planned. Risk management can help reduce the likelihood and affects of risks.
Risk management is important as it helps the team accomplish the project with as little
trouble as possible.
As a professional scientist, engineer, or project manager, you will be required to help get the
job done. Excuses (whether real or imaginary) generally do not buy any sympathy. For
instance, in the event of a surprise problem which causes project delays, it is all to easy to
deflect responsibility with victim phrases such as, "I did my part, but the other guy did not."
or "We had an unexpected problem which caused us to fall behind schedule." Managers,
professors, CEOs typically do not look favorably on people who invoke victim phrases. As a
result, people who fall back on these types of phrases, even if they are true, typically do not
go far in this world. You must learn how to deal with surprises and adversity, not be pushed
around by them.
By becoming a member of a team, each member dedicates themselves to the success of the
TEAM. If you are waiting on a team member to accomplish a task and they are behind, it is
your responsibility to help them in any way you can. If you cannot help them, you must make
sure they get the help to accomplish their task. The victim phrase does not absolve you of any
responsibility, rather it makes you look like you are not a team player.
Risk management can be a complex process, for our purposes. You may want to pay special
attention to risks that are so great, that they could "kill" the whole project. A member of the
group should be responsible for monitoring this risk throughout the project.
Stage 5: Develop a schedule
A schedule is the arrangement of tasks, people responsible for these tasks, and a timeline for
a project. Pert charts and Gant charts are examples of useful tools used in scheduling
activities. They allow the team to look at the architecture (structure) of the project and easily
216
identify responsibilities. The charts can serve as a document that people use in their planning
as a visualization tool to see how tasks depend on each other.
The basic format of a gant chart consists of a listing of tasks on the left hand side, followed
by the start date, number of days to complete, and a finish date. Each task should be assigned
one or more owners. To the right of the text listing is a graphical representation of the task
duration in the context of the project time line.
After the chart is made, look for conflicts of resources. For instance, make sure that team
members are not assigned too many tasks during a given time period. For instance, in the
schedule bellow, Lisa appears to be busier than her team mates on July 2nd and 3rd. Also make
sure that different tasks which require the same machines or rooms are not scheduled for use
at the same time. Make the changes and obtain agreement from the group that this is the
schedule that is to be followed. It might be wise to review the risks dur ing this time and
adjust parts of the schedule if it would help.
Figure 20.2: Gant Chart
Source: (MITOPENCOURSEWARE, 2008)
Microsoft project is also a project management tool. Project Management usually follow the
system development life cycle (SDLC) phases as discussed earlier in unit 18.
Stage 6: Execute the schedule
Every team member should know what they have to do and should have the right resources to
get the job done. They should know what the risks are and have back up plans in case of
trouble. During this stage, the project manager is responsible for coordinating, though group
members should communicate among themselves as required. If a group member feels he is
going to go over time or budget, it is their responsibility to bring it up to the group as soon as
possible. This way, resources can temporarily be shifted to help keep the team member on
schedule.
217
Each group member should document their activities. This is important as human memory is
shaky at best and it is likely that each team member will be required to recall details of their
activity. There is nothing more frustrating to a manager than to hear an employee say, "I can't
remember what I did." If one can't remember, how can the team trust that what they did was
correct? Documentation is the responsibility of the team members and will often be a saving
grace for them.
It is likely that surprises and conflicts may occur during the course of the project. It is
important to remember that it is the team's responsibility to make the project happen. If there
are problems, the team should help figure them out. If there are conflicts, the team should act
together to resolve them. This can be facilitated by regular meetings (daily, weekly, monthly,
whatever is practical) of the team. At the meetings the team should review the schedule and
the status (complete or not complete) of the project goals. Once the goals are accomplished,
the project is complete.
Stage 7: Finish the project and assessing performance
After the goals have been achieved, it is good practice to evaluate the performance of the
project team. This is where a good deal of learning and experience is gained. It will help
prevent similar problems in future projects.
4.0
CONCLUSION
Project Management provides the basic skills and knowledge needed to effectively manage a
group project through project scheduling, understanding and handling risk. Project
management can be managed by either an IT staff or a Specialist with management skills or
by Software (Microsoft project).
5.0
SUMMARY
In this unit, you learnt that:
•
Project management is a team work
•
Responsibilities should be shared among team members
•
Project Managers are designed to schedule, plan, and control project resources.
•
Pert charts and Gant charts are tools used in scheduling activities
•
Having a vision, setting a goal and working towards achieving it reduces missing
target.
218
6.0
TUTOR MARKED ASSIGNMENTS
a. In the project management steps outline which is the most important? And why?
b. Why do you need a backup plan(s) in project management?
c. What do you consider to be the basic inputs in a project?
d. What are the don’t(s) in planning a project?
7.0
FURTHER READINGS/REFERENCES
•
Massachusetts Institute of Technology, MITOPENCOURSEWARE. (2008).
Retrieved August, 2009, from http://
ocw.mit.edu/courses/electrical-engineering-and-computer-science/
•
Smith, J. (2009). Jan’s Web Work and Experiments. Retrieved August 15, 2009,
from http://www.jegsworks.com.
•
Retrieved August 8, 2009, from http://www.webopedia.org
•
Retrieved August 8, 2009, from whttp://www.wikipedia.org
219
MODULE 4
UNIT 21
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
WEB BASED APPLICATION
1.0
Introduction................................................................................................................209
2.0
Objectives...................................................................................................................209
3.0
Main Content ….........................................................................................................209
3.1
How Web-Based Application Work...............................................................209
3.2
Procedures of Using Web-Based Application................................................210
3.3
Forces behind Web-Enabled Systems…........................................................211
3.3.1 Extensible Markup Language (XML) …...........................................211
3.3.2 Web Services…..................................................................................213
4.0
Conclusion….............................................….............................................................216
5.0
Summary….............................................…...............................................................216
6.0
Tutor Marked Assignment….............................................….....................................216
7.0
Further Readings/References….................................................................................216
220
1.0
INTRODUCTION
In Unit 16, you learnt about the WWW, in unit 19 you were introduced to how applications
are made open to users at the enterprise level. This unit will introduce you to how to an
emerging trend, however, it is to free users from owning and storing applications by using
Web-based applications.
2.0
OBJECTIVES
By the end of this unit, you should be able to:
•
•
•
•
3.0
Distinguish between the purposes of XML in Web-enabled applications.
Identify the six advantages of XML.
Explain the potential benefit of Web services to enterprises IT applications.
Identify how Web based application work
MAIN CONTENT
APPLICATION SERVICE PROVIDER (ASPS)
Special web sites, called Application Service Providers (ASPs), allow access to their
application programs. To use one of these Web-based applications, you would connect to the
ASP, copy the application program to your computer system’s memory, and then run the
application. Most ASPs provide access to a wide range of application programs and charge a
fee for their services
3.1
Step 1:
HOW WEB-BASED APPLICATION WORK
Connect
The user connects to a Web-site known as application service provider (ASPs). While some
ASPs are free, most charge a fee to access and to use their applications. These applications
may be general purpose application such as Microsoft Office applications or specialized
applications such as Web authoring programs. The user then requests a specific application to
use.
221
Step 2:
Download
The Application Service Provider (ASP) downloads or sends a copy of all or part of the
requested application to the user. This copy is stored unto the user’s hard disk drive and is
ready to be run. The copy will remain their either for a specific period of time or until the
user runs and then exits the program.
Step 3:
Run
The user runs the application form his hard disk drive. For example a user might download
Microsoft Word document and use it to create a document.
Step 4:
Save and Exit
When the user has completed work with the application, the created files can be saved on the
user’s computer system and/or at the ASP. The user then exits the application program.
Step 5:
Remove Application
Once the user has exited the program, the program is automatically erased from his/her hard
disk and is not available to be run again. If the user wants to run the program again he/she
must start again with step 1.
3.2
PROCEDURES OF USING WEB-BASED APPLICATION
Registration: several ASP sites exist on the Web and some of their services are free. One of
the best known site is WebOS. Their only requirement is that you register for their services.
Accessing Applications: each time you connect to the WebOS site and log in, your Webbased desktop will appear. It will display numerous icons that can be used to access Webbased applications. These include notes, personal information manager, calendar, and a
variety of games.
Web-Based Desktop: the Web-based desktop looks and operates like the traditional windows
desktop. It consist of a variety of icons that are used to load and run applications.
222
3.3
FORCES BEHIND WEB-ENABLED SYSTEMS
Web-enablement: The tendency of systems developers to incorporate features of the Internet
in enterprise systems.
•
Widespread Use of Browsers
– New computers shipped with Web browsers
– Large installed base of browser users
– Browsers appearing on other IT devices
•
•
Flexibility
– Plug-ins: Software programs that extend the capabilities of your Internet
browser, giving it added features.
Universal front-end application
•
Legacy System
– Legacy System: Refers to the many mainframe, midrange, client/server or PC
applications that are used to manage business functions.
•
Interconnected Enterprises
–
Interoperability: The perfect exchange of data and information in all forms (data,
text, sound, and image, including animation) between the individual components of an
application (hardware, software, and network).
Heterogeneous Applications: May be written in different programming languages,
run on different types of computers, and use varying communications networks and
transmission methods.
–
3.3.1 EXTENSIBLE MARKUP LANGUAGE (XML)
Developers can design their own customized markup languages for describing data.
•
Structure of XML
223
Figure 21.1 Sample XML code for Airline flight Reservation.
Source: (Senn, 2004).
•
–
–
–
–
–
–
•
XML Advantages
Web-based
Extensible
Computer and software platform independent
Facilitates end-to-end application integration
A public, license-free standard
Has widespread vendor support
Document Type Definition (DTD): Defines the vocabulary (or standard) to
make the data easily understandable and useable.
Figure 21.2 Sample Document Type Definition (DTD).
Source: (Senn, 2004).
224
•
Presentation Using XML Style Sheets
– XML Style sheet Language (XSL): Created by developers or publishers of
XML data to manage the display and presentation of information in a
document.
•
Processing XML
Figure 21.3 Processing of XML Components.
Source: (Senn, 2004).
Figure 21.4 XML interface for Web-enabled Legacy System.
Source: (Senn, 2004).
225
3.3.2 WEB SERVICES
Web Services are Modular Internet applications that perform a very specific function or task.
•
Simplified Object Access Protocol (SOAP): The protocol used by an application to
invoke a Web service located on another computer.
Figure 21.5 Interplay between Web Services Participants.
Source: (Senn, 2004).
•
Web Services Description Language (WSDL): Describes the capabilities offered by a
specific Web service as well as the protocols and formats the service uses.
Figure 21.5 Web Services Description Language (WSDL).
Source: (Senn, 2004).
226
•
Universal Description, Discovery, and Integration (UDDI): A worldwide directory
for registering, finding, and using Web services.
– Yellow Pages: Describe the services offered by UDDI.
– Green Pages: Describe how an application can use the Web Services.
Figure 21.7 Universal Description, Discovery, and Integration (UDDI).
Source: (Senn, 2004).
Table 21.1
Technologies of Web Services and Principles
S/No.
Technology
1
Extensible Markup Language
2
3
4
Acronym
XML
Simple object access protocol
SOAP
(sometimes known as services
oriented Architectural Protocol)
Universal Discover,
UDDI
Description and Integration
Web Service Description
Language
WSDI
Source: (Senn, 2004.
227
Function
XML is a set of rules for creating tags
that describe the layout and content of
Web data.
Protocol for invoking remote Web
services objects using XML
XML-based public directory services that
provides information about available
Web services
Protocol that describe the capabilities of a
Web service object
4.0
CONCLUSION
Some suggest that Web-based applications may replace traditional application software
sometime in the future. They point out that Web-based applications offer advantages beyond
universal access to software and to data. One advantage is that user may no longer need to
upgr ade software on their hard disk when a new version becomes available. One challenge of
the Web-based applications relates to privacy and security of personal data stored as an ASP.
5.0
SUMMARY
In this unit you learnt that:
•
•
•
•
6.0
The concepts of Internet and WWW brought a lot of opportunities, where you can
exchange documents and now use applications on the fly.
Web based applications provide and ease to the high cost of maintaining software and
the ICT department of most organizations.
One challenge relates to privacy and security of personal data stored as an ASP.
To use the Web application you need to- Register, Access the application and the
Web-Based Desktop
TUTOR MARKED ASSIGNMENT
a. What is the different between Web based application and personal/enterprise
applications?
b. What are Heterogeneous Applications?
c. What are the basic Technologies of Web Services and their Principles?
d. What are the Advantages of XML?
7.0
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
228
MODULE 4
UNIT 22
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
INFORMATION SYSTEMS IN THE ENTERPRISE
1.0
Introduction................................................................................................................218
2.0
Objectives...................................................................................................................218
3.0
Main Content…………………..................................................................................218
3.1
Enterprise Information Systems.....................................................................218
3.1.1 The Transaction-Processing Sequence and TPS
Output and Reports............................................................................218
3.1.2 Management Information System (MIS) ..........................................219
3.1.3 Decision Support System (DSS) .......................................................220
3.1.4 Group Support System (GSS) ...........................................................220
3.1.5 Executive Support System..................................................................221
3.1.6 Expert Support System.......................................................................221
3.2
IT for Manufacturing, Automation and Control.............................................222
3.3
Enterprise Resource Planning System...........................................................223
3.4
Strategic Role of ICT.....................................................................................224
3.4.1 Competitive Strategy..........................................................................225
3.4.2 Value Chain........................................................................................227
3.5
Creating A Strategic Role For Information Systems......................................227
4.0
Conclusion..................................................................................................................228
5.0
Summary....................................................................................................................228
6.0
Tutor Marked Assignment.........................................................................................228
7.0
Further Readings/References.....................................................................................228
229
1.0
INTRODUCTION
In module 1: you learnt about how data is being processed, module 2: how data is housed,
and module 3: how data is distributed. This unit will introduce you to the flow of data in a
business organization to achieve an optimum goal.
2.0
OBJECTIVES
After you have read this unit, you should be able to know:
•
•
•
•
3.0
The types of Information System and their Characteristics
The Generic Competitive Strategies in Business
The strategic role of an IT
What is Enterprise Resource Planning System
MAIN CONTENT
Information System: A system in which data and information flow from one person or
department to another.
3.1
ENTERPRISE INFORMATION SYSTEMS
•
Enterprise Information System/Business Information System: Used to refer to the
family of IT applications that underlies the activities of running and managing a
business.
•
Transaction-Processing System (TPS): A shared business information system that
uses a combination of information communication technology and manual procedures
to process data and information and to manage transactions.
3.1.1 THE TRANSACTION-PROCESSING SEQUENCE AND TPS OUTPUT AND
REPORTS
– Action Document: A document designed to trigger a specific action or to
signify that a transaction has taken place.
– Detail Report/Transaction Log: A report describing each processed
transaction.
– Summary Report: A report that shows the overall results of processing for a
period of time or for a batch of transactions and includes a grand total for all
listed transactions and the average transaction amount.
– Exception Report: A report that lists unusual, erroneous, or unacceptable
transactions or results.
– Updated Master Data: An adjustment of all records in a system in response to
a processed transaction.
230
Characteristics of TPS
–
–
–
–
–
Processes high volume of similar business transactions
Supports multiple users in routine, everyday transactions
Use relatively simple procedures to control processing and to ensure accuracy
Produces documents and reports
Updates files and databases
Figure 22.1 The Transaction-Processing Sequence and TPS Output.
Source: (Senn, 2004).
3.1.2 MANAGEMENT INFORMATION SYSTEM (MIS)
Management Report System/Management Information System (MIS) a business information
system designed to produce the information needed for successful management of a
structured problem, process, department, or business.
Characteristics (MIS)
–
Uses data captured and stored as a result of transaction processing
–
Reports data and information rather than details of transaction processing
–
Assist managers in situations, evaluating conditions, and determining what
actions need to be taken.
–
Supports recurring decisions
–
Provides information prespecified reports formats, either in print or on-screen.
231
3.1.3 DECISION SUPPORT SYSTEM (DSS): a business information system designed to
assist in decision making where the decision process is relatively unstructured and only part
of the information needed is structured in advance.
Characteristics DSS
–
Assist people who make decisions where information requirements are not
known in advance.
–
Support problem solving and decision making where the situation is only
partly structured
–
Provides information needed to define and solve the problem
–
Works both with files and database, as well as with people working online
with the system.
–
Provides information in a format determined by the recipient at the time of
need.
3.1.4 GROUP SUPPORT SYSTEM (GSS): a business information system that permits
people to process and interpret information as a group, even if they are not working face-toface.
Characteristics GSS
–
Supports situations that are not fully structured
–
Assists in analyzing the problem under consideration
–
Is used by groups or team rather than individuals
–
Emphasizes communication and generation of ideas and information
–
Permits communication among team members at different locations, who
participate through communication networks
–
Involves a facilitator who keeps the group focused on the problem at hand and
draws ideas out of group members
–
Generates a database of the group’s questions, comments, and ideas rather
than a traditional report.
232
Figure 22.2 Group Support System (GSS).
Source: (Senn, 2004).
3.1.5 EXECUTIVE SUPPORT SYSTEM
Executive Support System (ESS)/Executive Information System (EIS) is an interactive
business information system designed to support executives that is capable of presenting
summary information on company and industry activities.
Characteristics ESS
– Offers quick, concise updates of business performance
– Permits scanning of data and information on both internal activities and the
external business environment
– Highlights significant data and information in summary form
– Allows the user to access data supporting the summary information
3.1.6 EXPERT SUPPORT SYSTEM
• Expert Support System/Expert System: A business information system that uses
business rules, regulations, and databases to evaluate a situation or determine an
appropriate course of action.
•
Rule Base/Knowledge Base: A database of rules in an expert system.
Characteristics Expert System
– Diagnoses problems and may recommend a cause of action
– Computes data an d applies the expertise of a human specialist to a situation
233
– Has a limited scope of application
– Relies on rule base
– Processes data entered by people interacting with the system as well as details
retrieved from other information systems.
Figure 22.3
Expert System Embedded in Order Entry Portion of an Auto Manufacturing
System.
Source: (Senn, 2004).
3.2
•
IT FOR MANUFACTURING, AUTOMATION AND CONTROL
Computer-Integrated Manufacturing (CIM): A manufacturing system that uses
computers to link automated processes in a factory to reduce design time, increase
machine utilization, shorten the manufacturing cycle, cut inventories, and increase
product quality.
•
Manufacturing Cell: A group of machines working together in computer-integrated
manufacturing.
•
Material Requirements Planning (MRP): A system that tracks the quantity of each
part needed to manufacture a product; essentially, an important component of MRP II.
•
Manufacturing Resource Planning (MRP III): An advanced MRP system that ties
together all the parts of an organization into the company’s production activities.
234
Figure 22.4 The Components of Manufacturing Resource Planning.
Source: (Senn, 2004).
•
Computer-Aided Design (CAD): A system that uses a powerful computer graphics
workstation to enable product designers and engineers to draw design specifications
on a display screen.
•
Computer-Aided Manufacturing (CAM) Systems: A system that relies on IT to
automate and manage the manufacturing process directly.
•
Flexible Manufacturing: A manufacturing system that automatically sets up
machines for the next job, thus reducing setup time and making smaller job runs
feasible.
•
Concurrent Engineering: A design and manufacturing method in which team
members work across their departmental functions to evaluate the activities of many
departments and manage the product development process.
•
Robot: A computer-controlled device that can physically manipulate its surroundings.
•
Computer Vision System: A system that uses computer sensors to detect shapes,
images, and varying levels of detail.
3.3
•
ENTERPRISE RESOURCE PLANNING SYSTEM
Enterprise Resource Planning (ERP) System: Large scope, unified application
programs that integrates many transaction processing and information systems
application features.
235
Figure 22.5 Enterprise Resource Planning System Integrates Functions.
Source: (Senn, 2004).
Figure 22.6 Modular Structure of SAP’s R/3 ERP Software.
Source: (Senn, 2004).
3.4
•
STRATEGIC ROLE OF ICT
Strategic Information System: Information technology application that changes the
way a firm competes, providing a capability so valuable that it enables the firm to
gain a substantial competitive advantage against its competitors.
236
•
Competitive Advantage: Occur when an enterprise has the ability to outperform rivals
on a primary performance goal – often profitability – or some other dimension.
3.4.1 COMPETITIVE STRATEGY
The means by which a firm seeks to gain an advantage over its competitors.
•
Low-Cost Leadership: Offers an enterprise great flexibility in dealing with any
suppliers that raise their prices to the firm, as well as buyers seeking to drive down the
pr ices they pay.
•
Product Differentiation
– Differentiation: A product that is perceived by customers as having unique
features in comparison to competitive items.
•
Focus on a Market Niche
– Market Niche: A focal point for a product or service; it is a subset of the
entire industry or segment of the market.
Figure 22.7 Three Generic Competitive Strategies.
Source: (Senn, 2004)
237
Table 22.1
Generic Competitive Strategies in Business
STRATEGY
Low cost leadership
Product differentiation
Focus on a market niche
DESCRIPTION
• Out perform other firms in the industry by providing products
or services at a lower cost than competitors while sustaining
or exceeding quality and services levels they provide
• Provides competitive advantage when dealing with suppliers
and buyers, and when offering substitute products or services
• Provides a product or services that is generally recognized as
distinct from competitors.
• Results in brand loyalty and avoids the necessity to take a
low-priced position; also effective in competing against
substitutes.
• Identify and compete in a market segment in which
competitive advantage may be gained by concentrating on a
specific buyer group, product line, or geographical area.
• Provides advantage of better service to customers, often at
lower costs, while producing better customer loyalty.
Source: (Senn, 2004).
Competitive Forces
Figure 22.8 The five Forces Influencing the Advantage a Firm can Gain.
Source: (Senn, 2004).
238
3.4.2 VALUE CHAIN
• Value Chain: A set of activities that is relevant to understanding the bases of cost and
potential sources of differentiation of a firm.
•
Primary Value-Chain Activities: The basic business processes fundamental to any
industry.
– Inbound Logistics
– Operations
– Outbound Logistics
– Marketing and Sales
– Service
•
Support Value-Chain Activities: Those activities that occur to facilitate the primary
activities.
– Procurement
– Technology Development
– Human Resource Management
– Firm Infrastructure
Figure 22.9 The Value Chain.
Source: (Senn, 2004).
3.5
CREATING A STRATEGIC ROLE FOR INFORMATION SYSTEMS
To determine whether information technology can be developed to serve a strategic role, ask
the following five questions:
– Change the basis of competition?
– Build barriers to new entrants?
– Build in switching costs to customers?
– Strengthen a firm’s power in dealing with suppliers?
– Generate or serve as new products?
239
4.0
CONCLUSION
Managing a business Information System require providing technical resources and
generating the information that the business need to run effectively and efficiently. This is
achieved by making data and information to flow in an organization through functional areas
and between management levels.
5.0
SUMMARY
In this unit, you learnt that:
•
•
•
•
•
6.0
Shared business information system uses a combination of information
communication technology and manual procedures to process data and information
and to manage transactions.
Business information system can permits people to process and interpret information
as a group.
Business information system uses business rules, regulations, and databases to
evaluate a situation or determine an appropriate course of action.
Business information systems establish set of activities that are relevant to
understanding the bases of cost and potential sources of differentiation of a firm.
Business information system is a firm that seeks to gain an advantage over its
competitors.
TUTOR MARKED ASSIGNMENT
a. What are the characteristics of the management information systems?
b. What are the technologies used in the manufacturing industry?
c. Define value chain.
d. What are the questions asked when creating a strategic role for an IS.
7.0
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
240
MODULE 4
UNIT 23
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
ISSUES IN INFORMATION TECHNOLOGY
1.0
Introduction………...…….........................................................................................230
2.0
Objectives...................................................................................................................230
3.0
Main Content..............................................................................................................230
3.1
Security.........................................................…..............................................230
3.1.1 Types of Security Breach...................................................................230
3.1.2 Results of Security Breach.................................................................231
3.1.3 Sources of Security Breach................................................................231
3.1.4 Security Measures..............................................................................232
3.2
Reliability................................................……………...................................236
3.2.1 Ensuring It Service Reliability...........................................................236
3.3
Ethics..............................................................................................................236
3.3.1 Ethics and ICT Usage In Business………………............................236
3.3.2 An Ethics Challenge...........................................................................236
3.4
Privacy............................................................................................................237
3.4.1 Spam and Privacy...............................................................................237
3.4.2 Private Networks................................................................................237
3.5
Digital Piracy..................................................................................................237
3.5.1 Protecting Against Software Piracy...................................................237
3.6
Public Domain Software................................................................................238
3.7
Ergonomics....................................................................................................238
3.8
The Environment............................................................................................238
4.0
Conclusion..................................................................................................................239
5.0
Summary....................................................................................................................239
6.0
Tutor Marked Assignment.........................................................................................239
7.0
Further Readings/References.....................................................................................239
241
1.0
INTRODUCTION
In all the previous units you have been learning about the merits of ICT. This unit will
discuss about the demerits and the measures put in place to overcome them.
2.0
OBJECTIVES
After you have read this unit, you should be able to:
•
•
•
•
3.0
Identify the types of security breaches, sources of security breaches, and ways to
protect a system against intrusion
Describe the importance of ethics in the use of information technology
Describe the concern over piracy of digital content.
Understand the reliability of IT systems
MAIN CONTENT
3.1
SECURITY
Security is the means of safeguarding and protecting an enterprise’s information technology
assets, that is by keeping away from criminals, natural hazards, and other threats, while a
breach is a breakdown in security.
–
–
–
–
Site Security
Resource Security
Network Security
Service Security
•
Security Program: The policies and protective measures that will be used, the
responsibilities of individuals involved in maintaining security, as well as the
responsibilities of those who abide by established security policies.
•
Harden: Designing a security program to a potential IT target, making the level of
effort greater than the value of breaking into a system, network, or facility.
3.1.1 TYPES OF SECURITY BREACH
• Intrusion: Forced and unauthorized entry into a system.
•
Interception: Aimed at preventing the capture of data and information transmitted
over an enterprise network or other communications link.
242
3.1.2 RESULTS OF SECURITY BREACH
•
•
•
•
•
Destruction of Resources
Corruption of Data and Applications
Denial of Services
Theft of Services
Theft of Resources
•
Denial-of-Services Attack: Depriving, usually intentionally and temporarily, an
enterprise or its users of the services they would normally expect to have, usually
involving a network service (such as e-mail) or access to a location on the network
(such as a Web site).
Internet Scam: are fraudulent or deceptive acts or operations designed to trick
individuals into spending their time and money with little or no return. Common
scams include identity theft, chain letters, auction fraud, vacation prizes, and advance
free loans. Almost all Internet scams initiated by mass e-mails.
Malicious programs: also known as malware (malicious software), include viruses,
worms, and Trojan horse.
•
•
– Viruses migrate through networks and operating systems and most attached to
programs and databases.
– Worms are special viruses that self replicate to slow or stop a computer’s
operation
– Trojan Horses are programs that come into a computer system disguised as
something else. While not a virus, Trojan horses deposit viruses onto
unsuspecting computer systems.
3.1.3 SOURCES OF SECURITY BREACH
•
Employees
This is the largest category of computer and enterprise criminals where an employee
(insider) who gain access to certain records or files without prior permission in order
to tamper (manipulate figures, steal records or damage files).
– Identify Theft: Loss of personal identity through a security breach.
•
Computer Viruses
– Virus: A hidden program that alters without the user’s knowledge, the way a
computer operates or that modifies the data and programs stored on the
computer.
•
Hacker and Crackers: Hackers gains access to a system illegally for fun and
challenge while crackers do it for malicious purpose.
243
•
Organised Crime: including counterfeiting and forgery.
•
Terrorist: Someone who conducts a “premeditated, politically motivated attack
against information, computer systems, computer programs, and data, which results in
violence against non-combatant targets by sub-national groups or clandestine agent.”
A terrorist usually cause potential crime to satellites and wage economic warfare.
– Cyberterrorism: Terrorist attack on computer facilities in companies that rely
on IT to produce their services.
3.1.4 SECURITY MEASURES
Security involves keeping enterprise hardware, software, data and programs safe. Some
measures are encrypting messages, restricting access through passwords and firewalls,
anticipating disasters (hot sites are emergency facilities; cold sites are empty shells), backing
up data and storing the data in a safe remote location.
The general Security Policies and Procedures are:
–
–
–
–
–
–
–
–
–
–
•
Virus Protection Software/Antivirus
–
–
–
–
–
–
•
Change access passwords frequently
Restrict system use
Limit access to data
Set up physical access controls
Partition responsibilities
Encrypt data
Establish procedural controls
Institute educational programs
Audit system activities
Log all transactions and user activities
Norton
Bit defender
Kerpersky
Avast
Panda
PC Cillin
Digital Signatures
– Digital Signature Encryption: Relies on a mathematical coding scheme
designed to foil a virus’s attempt to attack programs and data.
244
•
Encryption
Figure 23.1 Encryption Procedure for Protecting Data and Messages.
Source: (Senn, 2004).
Methods of Encryption
– Public Key Infrastructure (PKI): A public key is made available in a directory
that all parties can search. Thus a sender wishing to transmit a secured message
searches a digital certificate directory to find the recipient’s public key, using it
to encrypt the message.
– Secure Electronic Transaction (SET): An adaptation of public key encryption
and the digital certificate (which the industry calls an electronic wallet) for
securing financial transactions over the Internet.
– Pretty Good Privacy (PGP): A program used to encrypt and decrypt e-mail and
to encrypt digital signatures, so the recipient knows the transmission was not
changed along the way.
– Virtual Private Network (VPN): A way to use a public telecommunication
infrastructure, such as the Internet, to provide secure communication between
individuals or client computers at remote locations and an enterprise network.
– Virtual Private Network
– Tunneling Protocols: By encrypting data at the sending end and decrypting it at
the receiving end, the protocols send the data (and if an enterprise chooses, the
originating and receiving network addresses as well) through a tunnel that
cannot be entered by data that is not properly encrypted
•
Firewall: A special-purpose software program located at a network gateway server.
•
Proxy Server: Act as an intermediary between a PC and the Internet, separating an
enterprise network from an outside network
245
Figure 23.2
A Hardware Firewall Protecting Against Unauthorized Access to a Private
Network.
Source: (Senn, 2004).
Figure 23.3
A Computer Firewall Protecting Against Unauthorized Access to a Private
Network.
Source: (Senn, 2004).
246
Figure 23.4
An overview of a Firewall Protecting Against Unauthorized Access to a
Private Network.
Source: (Senn, 2004).
Figure 23.5 Proxy Servers.
Source: (Senn, 2004).
247
3.2
RELIABILITY
Reliability: The assurance that computers and communications systems will do what they
should when they should.
3.2.1 ENSURING IT SERVICE RELIABILITY
• Fault-tolerant Computer: A computer designed with duplicate components to ensure
reliability.
•
Uninterruptible Power Supply (UPS) System: A system that ensures the continued
flow of electricity when the primary source of power fails.
•
Disaster Recovery Plan: A procedure for restoring data lost when a system stops
functioning.
•
Off-site Backup Facility: A backup computer center located away from a company’s
main facility.
– Hot Site: A fully equipped backup computer center to which a company can
take its backup copies of data and software and resume processing.
– Cold Site: A backup facility outfitted with electrical power and environmental
controls so that it is ready for a company to install a computer system.
3.3
ETHICS
Ethics are guidelines for moral computer use. The standards of conduct and moral behavior
that people are expected to follow are:
• Privacy – concerns collection and use of data about individuals
• Accuracy – relates to the responsibility of those who collect data to ensure
correctness.
• Property - relates to who owns the data.
• Access – relates to the responsibilities of those who have data to control and who is
able to use it.
3.3.1
•
•
•
•
•
•
•
ETHICS AND ICT USAGE IN BUSINESS
E-mail Privacy
Software Licenses
Software Copyrights
Hardware Access
Intellectual Property Ownership
File Access
Data Ownership
3.3.2 ETHICS CHALLENGE
• Developing a Code of Ethics
– Informed Consent
– The Higher Ethic
– Most Restrictive Action
– Kantian Universality Rule
248
– Descartes’ Change in Rule
– The Owner’s Conservative Rule
– The User’s Conservative Rule
•
Social Responsibility: The concept that businesses need to balance their commitments
to investors, employees, customers, other businesses, and the communities in which
they operate.
3.4
PRIVACY
What is Privacy?
Privacy in IT is the term used to refer to how personal information is collected, used, and
protected.
3.4.1 SPAM AND PRIVACY
•
Spam: Unsolicited e-mail.
•
Opt-in E-mail/Permission-based E-mail: If customers check a box agreeing to
receive postings about the company’s products, they have actually given approval for
the mailing.
•
Cookies: are specialized programs deposited onto you computer system that record
sites visited, activity at sites and other information.
– Traditional cookies – monitor activities at a single site
– Ad network cookies – also known as adware cookies, monitor activities
across all sites visited
– Web bugs – programs typically hidden within the HTML codes as a
graphic image. They migrate when ever an unsuspecting user visits a
web site containing a Web bug or open an infected e-mail message.
– Computer monitoring – record every activity and keystroke made on
your computer system. Also known as sniffer programs and keystroke
loggers, these programs are used by businesses, CIA, SSS, FBI, private
investigators and others.
A new program known as spy ware removal programs has recently evolved designed to
detect Web bugs and monitoring software.
3.4.2 PRIVATE NETWORKS
Many organizations monitor employee e-mail and computer files using special software
called snoopware. Most online information services restrict libelous, obscene, or other
offensive material.
3.5
•
DIGITAL PIRACY
Digital Piracy: The making of illegal copies of copyrighted information.
3.5.1 PROTECTING AGAINST SOFTWARE PIRACY
• Software Piracy: The making of illegal copies of software.
249
•
Software Copyright Protection
– Copyright: Legal protection of original works against unauthorized use,
including duplication.
•
Copy Protection: A software protection scheme that defeats attempts to copy a
program or makes the copies software unreliable
•
Software Site Licensing
– Site License: An agreement under which a software purchaser pays a fee to
the manufacturer to make a specified number of copies of a particular
program.
3.6
•
•
PUBLIC DOMAIN SOFTWARE
Public Domain Software: Any non copyrighted software that can be used by the
general public.
Shareware: Software that is given away and freely distributed. The developer retains
ownership, asks users to register with the owner, and requests a nominal fee for using
the program.
3.7
ERGONOMICS
Ergonomics is the study of human factors related to things people use, including computers.
•
•
•
Physical health problems and their solutions include:
Eyestrain and headache – take frequent breaks; avoid glare on the monitor.
Back and neck pain – use adjustable chairs, tables, monitor stands, keyboards, and
footrests.
•
Repetitive Strain Injury (RSI), also known as repetitive motion industry, includes
carpal tunnel syndrome – take frequent breaks, use good posture; adopt healthy
lifestyle; use ergonomic keyboards.
3.8
THE ENVIRONMENT
Microcomputers are the greatest users of electricity in the work place. The Energy Protection
Agency EPA has established the Energy Star Program ESP to promote energy efficient
computer use to reduce or eliminate hazards. The computer industry has responded with the
concept of the GREEN PC.
The Green PC
The basic elements of the green PC include:
• System units with energy-saving processors, sleep-mode capability, efficient adapters,
and no cooling fans.
• Display units that replace CRT displays with flat panels, use special power-down
monitors, and use screen savers software.
• Manufacturing that eliminates or reduces the use of harmful chemicals such as
chlorofluorocarbons (CFCs), nickel, and other heavy metals.
250
Personal Responsibility
As a responsible computer user, you can help protect the environment by:
• Conserving energy by turning off computer systems at night and using screen-savers.
• Educating yourself and others about ecological dangers and using ecologically sound
products.
• Recycling paper, computer boxes, packaging materials, printer cartridges, and floppy
disks.
4.0
CONCLUSION
To be a competent and knowledgeable ICT end user you need to be aware of the potential
impact of technology on people and your surrounding. You need to be sensitive and
knowledgeable about personal privacy, organizational security, ergonomics, and the
environmental impact of technologies.
5.0
SUMMARY
In this unit you learnt that:
•
•
•
•
6.0
Security involves keeping enterprise hardware, software, data and programs safe.
Reliability is the assurance that computers and communications systems will do what
they should when they should
Privacy refers to how personal information is collected, used, and protected.
Ethics are guidelines for moral computer use.
TUTOR MARKED ASSIGNMENT
a. What are the sources of security breach
b. Differentiate between security and breaches
c. What are the measures put in place to avoid software piracy?
d. What are the measures taken to ensure ICT service reliability?
7.0
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
251
MODULE 4
UNIT 24
MANAGING INFORMATION AND COMMUNICATION
TECHNOLOGY APPLICATIONS IN THE ENTERPRISE.
CAREERS IN ICT.
1.0
Introduction................................................................................................................241
2.0
Objectives...................................................................................................................241
3.0
Main Content….............................................….........................................................241
3.1
Careers............................................................................................................241
3.2
Other Areas of Expertise................................................................................243
4.0
Conclusion.................................................................................................................243
5.0
Summary….............................................…...............................................................244
6.0
Tutor Marked Assignment..........................................................................................244
7.0
Further Readings/References.....................................................................................244
252
1.0
INTRODUCTION
In the previous units you learnt about the world of Information and communication
technology. This unit will take you round the various positions and professionals in the ICT
world.
2.0
OBJECTIVES
After you have read this unit, you should be able to know:
• How to build a Career in ICT
• How to update your professional Curriculum and become marketable
• Which ICT field is related to you work or field of specialist?
• Who to contact when you have a job at hand
3.0
MAIN CONTENT
3.1
CAREERS
A few important career development paths are:
a.
Webmaster
Webmasters develop and maintain Web sites and web resources. The job may include backup
of the company Web site, updating resources, or developing of new resources. Webmasters
are involved in the design and development of website. Part of their job may also include
monitoring and updating the interface design. Some webmasters monitor traffic on site.
Webmasters may also work with marketing personnel to increase the site traffic and may be
involved in development of Web promotions.
b.
Computer Trainers
Computer trainers instruct new user on the latest software or hardware. They are usually
expected to prepare new materials for instruction and may be asked to write and maintain
course manual. A position may also include design and development of a website for the
course. Computer trainers typically teach new users how to use the latest software and
hardware. Experience with the most popular business software is an advantage.
c.
Desktop publisher
Desktop publishers use computers to format and create publication-ready material. They may
create books, magazines newsletter, and newspapers on computers using special applications
software’s large part of the job is designing page layout, importing text, and manipulating
graphics. Most desktop publishers work for companies that handle commercial printing
accounts.
d.
Computer support specialist
Computer support specialists provide technical support to customers and other users. They
may also be called technical support specialist or help desk technicians. They manage the
everyday problems faced by computer users. They resolve common networking problems and
may use troubleshooting programs to diagnose problems.
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e.
Computer technician
Computer technicians may repair and install computer components and systems. They may
work on everything from personal computers to mainframe servers or printers. Some
Computer technicians are responsible for setting up and maintaining computer networks.
Experience computer technicians may work with computer engineers to diagnose problems
and run routine maintenance on complex systems.
Certification – CompTIA’s A+ hardware examination and Network+
f.
Data entry
Data entry workers input customer information, lists, and other type of data. Input devices are
typically limited to keyboards, mice, and scanners. Because the accuracy of recorded data is
so Important, data entry workers are often required to verify the accuracy of data they and
others have entered.
g.
Technical writers
Technical writers prepare instructional manuals, technical reports, and other scientific or
technical documents. Most Technical writers work for software firms, government agencies,
and research institutions.
h.
Software engineers
Most Software engineers analyse user need and create application software. Software
engineers usually have experience in programming, but focus on the design and development
of programs using the principles of mathematics and engineering. They rarely write codes
themselves.
i.
Network administrator
Network administrator manages a company’s LAN and WAN networks. They may be
responsible for the design, implementation and maintenance of networks. Responsibilities
usually include the maintenance of both hardware and software relating to a company’s
intranet and internet networks. Some are responsible for planning and implementing the
security measures as well.
Certification - Microsoft Certified Systems Engineer (MCSE), Certified Novell
Administrator (CNA), and Certified Novell Engineer (CNE).
j.
Cryptographer
Cryptography is the science of disguising and revealing encrypted information. In ICT
cryptography means keeping any intercepted information private. For example information
like financial data, banking and credit card information used in online shopping or private email and correspondence. Cryptographers design systems, break systems, and do research on
encryption.
k.
Information system manager
Information system managers oversee the work of programmers, computer specialists, system
analysts, and other computer professionals. They create and implement corporate computer
policy and systems. These professionals consult with management, staff and customers to
achieve goals.
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l.
Database administrators
Database administrators use database management software to determine the most efficient
ways to organize and access a company’s data. They are responsible for maintaining database
security and backing up systems.
Certifications – MySQL Server, Oracle, and Sybase.
m.
Systems analyst
A Systems analyst follows the steps described in the systems development life cycle.
Analysts plan and design new systems or reorganize a company’s computer resources to best
utilize them.
n.
Computer programmers
Computer programmers create, test, and troubleshoot programs used by computers.
Programmers may also update and repair existing programs.
Certifications – Java, C++, Visual Basic and knowledge of SQL.
3.2
•
4.0
OTHER AREAS OF EXPERTISE/ORGANAISATION
Hardware
– Cisco Products
– D-link
– Linksys
•
Software
– Microsoft Products
– Linux (Red Hat, Unbutu, and Fedora) – Open Source: Free
•
Database
– Oracle
– MySQL - Open Source: Free
•
Web design
– PHP - Open Source: Free
– Dream Weaver
CONCLUSION
Knowing the ICT positions and their responsibilities help you to prepare your CV and make
yourself marketable.
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5.0
SUMMARY
In this unit we learnt that
•
Most ICT professions does not require a degree in Computer Science
•
Professional Certifications will boost your CV.
•
You can start today and develop a career in ICT
•
Some key position requires knowledge in two or three field.
6.0
TUTOR MARKED ASSIGNMENT
a. Which fields are related in terms of hardware?
b. Which IT positions are unique?
c. Which IT position requires knowledge in all fields?
d. Which IT position is a top level position?
7.0
FURTHER READINGS/REFERENCES
•
Norton, P. (2003). Computing Fundamentals (5th Edition). United States of America:
Glencoe/McGraw-Hill.
•
O’Leary, T.J., O’Leary, L. I. (2004). Computing Today. New York, US: McGraw-Hill
•
Senn, J. A. (2004). Information Technology: Principles, Practices,
Opportunities (3rd Edition). New Jersey, US: Pearson Prentice Hall.
256
SOLUTIONS TO THE TUTOR MARKED ASSIGNMENTS
(TMA)
UNIT 1:
INFORMATION COMMUNICATION TECHNOLOGY: PRINCIPLES,
PRACTICES, AND OPPORTUNITIES
a. What is Information and Communication Technology? List its three main components.
ANS
A term used to refer to a wide variety of items and abilities used in the creation, storage, and
dispersal of data and information. Its three main components are computers, communications
networks, and know-how.
ICT three main components are:
–
Computers; used to process data into information,
–
Communications networks; transmission of information,
–
Know-how; the technology used for the transmission
b. List five ways by which information can be transmitted.
ANS
–
–
–
–
–
–
–
–
–
–
–
Writing
Typing
Printing
Telephone
Telex
Radio
Television
Fax
Satellite
Computer
E-mail
c. Name the three stages of information evolution.
ANS
– Agricultural Age: The period up to the 1800s, when the majority of workers were
farmers whose lives revolved around agriculture.
257
– Industrial Age: The period from the 1800s to 1957, when work processes were
simplified through mechanization and automation.
– Information Age: The period that began in 1957, in which the majority of
workers are involved in the creation, distribution, and application of information.
d. Why do we need computers to process data and information?
ANS
Information is the life wire of today’s organisations, especially business and industry. Every
organisation, regardless of its size and purpose, is concerned with processing data in order to
provide current and accurate information. Employees at every level within most organisations
use the computer, communication devices or results from these in the performance of their
everyday duties.
Organisations today now require tools that will enable them to get relevant information easily
and on time. A simple answer to this question is that traditional and manual methods of
processing data have now become inadequate for handling information needed for today’s
business organisations
UNIT 2:
ESSENTIALS OF COMPUTING
a. List the four categories of hardware with examples.
ANS
These devices that make up the hardware are classified into one of four units depending on
the role they play in the computer system as follows:
–
Input devices (Keyboard, Mouse, Scanner, Camera etc)
–
Output devices (Printers, plotters etc)
–
Storage (Hard disk, floppy disk, CD, flash drives etc)
–
System unit (SU).
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b. Define an operating system and an application program.
ANS
Operating System
An operating system is an integrated set of control programs designed to manage computer
resources and maximise the overall operating effectiveness of the computer system.
Practically speaking, operating systems determine the way we are able to use computers.
The implication of this is that users do not have to learn how to work with particular makes
of computers but with particular OS. Once a user can use an OS, he can work on all
computers that use those Operating systems. Examples of Operating systems in the market
today include:
Application Software
Application software consists of a number of programs designed to perform specific tasks for
users. A computer program giving instructions for the steps involved in preparing and
printing bills for the amount of water, gas and telephone used is a good example of
applications software.
Applications software may be provided by the computer manufacturer or supplier, but in
some cases the users produce their own applications software called user programs (e.g.
payroll programs, stock control programs etc).
c. Define four OS you know
ANS
– MS-DOS- Microsoft Disk Operating System; commonly called DOS and it is
used with a single microcomputer.
– NOVELL- Used in a network environment, where many computers are linked
together to share resources.
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– UNIX- used in a multi-user environment where many people can use one big
computer at the same time.
– Windows Operating System- Used with a single microcomputer or in a network
environment. Its graphical interface enables the user to have fun while
communicating with the computer. Some software’s are Window-driven such as
95, 98, Me, XP, Vista and Windows NT are self-sufficient.
d. Define the four kinds of systems program you know.
The four kinds of system programs are operating systems, utilities, device drivers, and
language translators.
–
Operating Systems (OS): coordinates resources, provide an interfaces between users
and the computer, and run programs.
–
Utility (service programs) performs specific tasks related to managing computer
resources.
–
Device Drivers: This is a program developed by the manufacturer of a device or
computer hardware component to make the devices work on different software
platforms. The examples of such devices are network interface cards (NIC), sound
cards, printers, and other computer peripherals.
–
Language Translator: converts programming instructions written by programmers
into a language that computers can understand and process.
UNIT 3:
THE SYSTEM UNIT
a. List the four elements to be considered when determining processor speed?
ANS
In determining Processor Speed, four elements are considered::
– System Clock
– Bus Width
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– Word Size
– Available Memory
b. What are the functions of the Central Processing Unit (CPU)?
ANS
The Central Processing Unit (CPU) is known to be the brain and the computational unit of the
System Unit (SU).It performs the following major functions;
– Co-coordinating the activities of all units or devices associated with the
comput er system.
– Accepting and executing instructions to cause the computer system unit to
perform tasks.
c. What is the difference between the System Unit and the Central Processing Unit?
ANS
The difference between the SU and the CPU are:
– The SU house the CPU and other hardware components.
– The CPU is the component in the SU that contains the Microprocessor in charge
of all the computations and logics.
d. Define Grid Computing?
ANS
Grid and Cloud Computing: A process that harnesses idle time on computers and then uses
them to provide processing for an application that needs more speed and capability than may
be available on a single computer, or even on a supercomputer
UNIT 4
INPUT DEVICES
261
a. List three pointing devices
ANS
Mouse/mice
Joystick
Light pen
Stylus
b. Which category of device is the Optical Character Recognition (OCR)?
ANS
It is a scanning device
c. What are the basic functions of a mouse?
ANS
–
clicking,
–
double clicking
–
dragging
–
right clicking
–
scrolling
–
pointing
d. What category of device is the joystick and what is it used for?
262
ANS
The Joystick is a pointing device used for playing computer games.
UNIT 5
OUTPUT DEVICES
a. Briefly define an output device
ANS
Output devices are devices through which computer transmits information to the outside
world. Output devices work to transform information processed in the computer, which is in
machine form, to human understandable forms e.g. text, pictures etc. With the aid of output
devices information can be viewed, heard, and printed. Example of output devices are:
b. Discuss the use of a data project and list its types.
ANS
Data Projector: Equipment connected to the computer’s display output port by a data cable
that is used to show the contents of a computer video display on a movie screen.
– Liquid Crystal Display (LCD) projector
– Digital Light Processing (DLP) Projector.
c. What does RGB stands for in a monitor?
ANS
RGB Display: A video screen display with the ability to create 256 colors and several
thousand variations on these colors by blending shades of red, green, and blue.
d. Define the following: film recorder, speaker and laser printer.
ANS
–
Film Recorder: An output device that transforms an electronic image on a computer
screen into a film image.
263
–
–
Speakers: - Speakers are connected to computers through Sound cards, so as to listen
to voice outputs.
Laser Printer: A nonimpact printer that uses laser beams to print an entire page at
once.
UNIT 6
STORAGE AND MEMORY
a. What does SAN stands for in storage?
ANS
SAN stands for Storage Area Network
S AN is a high-speed network or system that allows different kinds of storage devices, such
as tape drives and disk arrays, to be shared by all users through network servers.
b. What are the other magnetic disk storage systems?
ANS
–
USB Drives: Consisting of flash memory and a USB connection, it can read and write
data when connected to the computer’s USB port.
–
Zip Drive: A removable storage device that uses hard-shelled removable Zip disks,
which can store up to 750 MB of information.
–
Super Disk: A storage alternative developed by Imation (originally part of 3M Corp.)
that has a capability of 120 MB.
c. Is memory and storage the same? Explain.
ANS
NO- memory and storage are not the same the same
Although the functions of storage and memory are similar, they work in different ways.
–
There is more room in storage than in memory, just as there is more space in a file
cabinet than on a table top.
264
–
Contents are retained in storage when the computer is turned of, whereas the program
or data you put into memory disappear when you shut down the computer
–
Storage is very slow compared to memory, but it is much cheaper than memory.
d. What does the following means in memory?
ANS
– Byte: A storage location in memory; the amount of memory required to store
one digit, letter, or character.
– Kilobyte/K-byte/KB/K: One thousand bytes.
– Megabyte/M-byte/MB/Meg: One million bytes.
– Gigabyte/G-byte/GB/Gig: One billion bytes.
– Terabyte/T-byte/TB: One trillion bytes.
– Address: An identifiable location in memory where data are kept.
UNIT 7:
DATABASES
a. What is a database?
ANS
A database is a single organized collection of structured data, stored with minimum
duplication of data items so as to provide a consistent controlled pool of data. There are two
types:
–
Flat databases - A database that consists of a single table. E.g. Spreadsheets.
–
Relational Databases – Multiple joined tables. E.g. Access.
265
b. List two reasons for using database.
ANS
The following are reasons for using a database:
–
Enterprise Database: Large multiuser database systems developed and maintained by
IT professionals.
–
Personal Database (PC Database): Typically reside on personal computers and are
designed to support a particular function.
–
Storing Data
–
Retrieving Data
–
Query/Querying: A question to be answered by accessing the data in a database.
–
Editing: Adding, deleting, or changing the data about companies.
–
Organizing Data
–
Distributing Data and Information
c. What is Database Normalisation?
ANS
Database Normalisation is the process of structuring data to minimise duplication and
inconsistencies, by breaking down a single table into two or more tables and defining
relationships between those tables. The three levels in normalising a database are:
–
–
–
First Normal Form (1NF): There should be no repeating groups in a table. For
example, say you have a students table with the following structure:
Second Normal Form (2NF): No non-key fields may depend on a portion of the
pr imary key.
Third Normal From (3FN): No fields may depend on other non-key fields. In other
words, each field in a record should contain information about the entity that is
defined by the primary key.
266
d. What are the steps taken to design a Database Application?
ANS
Database Application is a computerized database routine for collecting, retrieving, or
manipulating data to meet recurring needs.
UNIT 8:
–
Study the Problem
–
Determine the Requirements
–
Design the Database
–
Create the Database
–
Design the Application
–
Create the Application
–
Test the Application
DATABASE MANAGEMENT SYSTEM (DBMS)
a. What is a DBMS?
ANS
Database Management System (DBMS): A program that makes it possible for users to
manage the data in a database in order to increase accessibility and productivity. Some
examples are: MS Access, dBase, FoxPro, Paradox, Approach, MySQL, and Oracle.
b. What are the advantages of using a Multidimensional Database?
ANS
Multidimensional Database extends two dimensional relational tables to three or more
dimensions sometime called hyper cube.
Advantages include:
–
Conceptualisation – database provides an intuitive model for complex data and
relationships.
267
–
Processing Speed – analyzing and querying is faster.
c. What is the difference between a Database and DMS?
ANS
A database is a single organized collection of structured data, stored with minimum
duplication of data items so as to provide a consistent controlled pool of data, while a
Database management system is a program which lets you manage information in databases.
It also controls the interface between the user and the data in the database.
d. Who is a DBA?
ANS
Database Administrator (DBA)
This is a person who acts as a special manager managing the database usually a staff in the
organisation. The DBA is also responsible for preparing manuals for the users of the system
describing the facilities the database offers and their uses and designing the data dictionary.
UNIT 9
DATABASE QUERIES
a. What are the modes of operation of a Query language?
ANS
Queries languages have two basic modes of operation:
–
Terminal Monitor Mode
The user is able to use query language at a terminal, in the same way a command
language interpreter is used. Ad-hoc queries are formulated to obtain data form
databases.
–
Embedded Query Language
The query language statements are included within the code of programs written
in some other programming language, eg. C or Oracle, and effectively because
part of the program, hence the term “embedded query language”.
268
b. What does the acronym SQL means? List its statement type
ANS
SQL means Structured Query Language
SQL basic statements are:
–
SELECT Statements
–
INSERT Statement
–
UPDATE Statement
–
DELETE Statement
c. What are the two types of queries you know?
ANS
–
Query by example (QBE) and
–
Structural query language (SQL).
d. List the two types of query windows in MsAccess.
ANS
–
Query Design View Window
–
Query Code View Window
UNIT 10:
ENTERPRISE DATABASES AND DATA WAREHOUSES
a. What are the Concurrency Procedures followed in Data Warehousing?
ANS
The Concurrency Procedures are:
269
–
Concurrent Data Sharing: A database procedure that allows several users to access
the database simultaneously.
–
Nonconcurrent Data Sharing: A database procedure that allows individuals to access
a database only when no other person or application is processing the data.
–
Record Locking: A concurrency procedure that prohibits another user from accessing
or altering a records that is in use.
–
File Locking: Used in systems that store unstructured information and have file-leve l
sharing.
–
Deadlock: A situation in which each user of a database is waiting for the others to
unlock a record.
b. List the functions of a DBMS
ANS
The Functions of DBMS are:
–
Integrating Databases
– Reducing Redundancy
– Sharing Information
– Maintaining Integrity
– Enabling Database Evolution
c. Identify the two most common distribution strategies used for database systems. Explain
each
ANS
The Distribution Strategies are:
–
Geographic Distribution Strategy: A database distribution strategy in which the
database is located in a region where the data and information are used most
frequently.
–
Functional Distribution Strategy: A database distribution strategy in which the
database is distributed according to business functions.
270
d. What items must be taken into account when designing a distributed database system?
ANS
Design Factors are:
– Storage Costs
– Processing Costs
– Communication Costs
–
Retrieval and Processing
– Reliability
– Frequency of Updates and Queries
UNIT 11
COMPUTER NETWORKS
a. What are the Advantages of Using Networks?
ANS
There are many possible advantages of using networks. The basic ones are:
– The sharing of resources (e.g computers and staff) and information
– The provision of local facilities without the loss of central control
– The even distribution of work, processing loads, e.t.c
– Shared risk and mutual support.
– Improved and more economic communication facilities in general, e.g. including
voice communications.
b. What does ISO means? How many layers are there in the OSI?
ANS
ISO means International Standard Organisation (ISO). The Open Systems
Interconnectivity (OSI) model has seven layers from the lowest to the highest as follows;
–
The physical control layer is the level of electrical connections, signal transmission
and data in raw form.
–
The data link layer is the level at which data is transmitted in small units using
suitable protocols to control and correct transmission.
271
–
The network layer is the level which provides control among adjacent sending and
receiving points in a network.
–
The transport layer is the level which provides an end-to-end service between host
computers. It deals with addressing, error controls and regulated data transfer.
–
The session layer is the level which handles the establishment of connections
between host and the management of the dialogue
–
The presentation layer is the level which handles the standard forms for presenting
data, e.g. the layouts used for VDU displays.
–
The presentation layer is the level which the user has control over in determining
what data is to be transmitted and how it is to be sent or received.
c. List the two types of network connection you know.
ANS
There are two basic types of network connections:
– Physical connections and
– Logical or virtual connections
d. Why do you join computers and other devices to form a network?
ANS
The objectives of setting up a network is:
–
To use hard discs, modems, printers, and other devices connected to other computers
on the network.
–
To let other people access your hard discs, modems, printers or other devices
connected to your computer on a network.
–
To gain access to files, folders, and other resources on other computers connected to
the network, &
–
To let other people on the network access files, folders and other resources on your
computer.
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UNIT 12
NETWORKING TECHNOLOGIES
a. Identify the types of Network Technology?
ANS
– Local Area Network (LAN): A network that interconnects computers and
communications devices within an office or series of offices; typically spans a
distance of a few hundred feet to several miles.
–
Wide Area Network (WAN): A network that connects sites dispersed across states,
countries, or continents.
b. What is Network Topology?
ANS
A network topology is the geometric arrangement or layout of computers in a network. The
following types of layouts are common:
–
Point-To-Point Network Topology
–
Bus Network Topology
–
Star Network Topology
–
Ring Network Topology, and
–
Tree Network Topology.
c. The
topology is a circular network with a computer in the center.
ANS
Star
d. Which type of wide area network is faster than the local area network
ANS
Metropolitan Area Network (MAN): A network that transmits data and information over
citywide distances and at greater speeds than a LAN.
e. Define high speed LAN.
ANS
273
High-Speed LAN Technologies
Today’s growing fast-changing networks are like growing communities; the traffic they
create tends to cause congestion and delays. To alleviate these problems, you can install
higher-speed
LAN technologies in your network that move traffic more quickly and offer greater datacarrying capacity than Ethernet.
UNIT 13
COMMUNICATIONS NETWORKS
a. What is a communication network?
ANS
Communications Network: A set of locations, or nodes, consisting of hardware, programs,
and information linked together as a system that transmits and receives data and information
b. List three network service applications you know.
ANS
– Electronic Data Interchange (EDI.
– Videotex.
– Videoconferencing
– Work Group Conferencing.
– Electronic Bulletin Board
– Electronic Funds Transfer (EFT).
– Voice Mail
–
Electronic Mail
c. What do you understand by the term network channels?
ANS
274
Network channels are medium used in a communication network. They are the physical or
cableless media that link the different components of a network.
–
Physical Channel
–
Wireless Channel
d. List the five Types of Transport Technology you know
ANS
–
Frame Relay.
–
Asynchronous Transfer Mode (ATM
–
Digital Subscriber Line (DSL)
–
Integrated Services Digital Network (ISDN)
–
Switched Multimegabit Data Services (SMDS
UNIT 14
ENTERPRISE AND WIRELESS COMMUNICATIONS NETWORKS
a. What is security in WLAN
ANS
Wireless LAN Security: the safeguarding or the network against unauthorized access.
–
Wired Equivalent Privacy (WEP): A system of security protection that is a
standard for encrypting data (converting the data into a protective code) over an
802.11 b wireless network.
–
Service Set Identity (SSID): An encrypted code keyed into the LAN devices, so
that only devices with similar code can access the network resources.
b. List the four types of wireless communication networks
ANS
–
Cellular Communication Service
–
Wireless LAN (WLAN)
–
Bluetooth Personal Area Network/Personal Area Network
275
–
Wireless Data Networks
c. Who is a Network Administrator?
ANS
•
A Network Administrator is the ICT professional responsible the management of a
network, consisting of those procedures and services that keep the network running
properly.
d. How many types of Enterprise Architectures do you know?
ANS
Enterprise Architecture is the structure of a communications network, which determines how
the various components of the network are structured, how they interact, and when
cooperation between the system’s components is needed.
– Centralized Architecture
– Distributed Architecture
– Combining Architectures (Hybrid Network: combines centralized and distributed
architectures )
UNIT 15
ESSENTIALS OF THE INTERNET
a. Identify the main functions of the Internet.
ANS
The Internet and the Web are used by billion of users in different countries in the world to
perform the following activities;
– Communicate
–
Retrieve
–
Research on the Web
–
Shopping or Cybermalls
b. When was the Internet launched and by who?
276
–
The Internet, or the Net, was launched in 1969 by the Advanced Research Agency
Network (ARPANET).
c. What is the difference between e-mail, instant message, and chat session?
ANS
–
E-mail or Electronic Mail:A service that transports text messages from a sender to
one or more receivers via computer.
–
Chat Session or Internet Relay Chat (IRC): A live interactive discussion in which
parties on the network exchange ideas and observation electronically.
•
–
Portal: A gateway or hub site, such as Yahoo!, that provides chat rooms.
Instant Messages: A combination of real-time chat and e-mail by which short text
messages are rapidly exchanged over the Internet, with messages appearing on
recipient’s display screen immediately upon arrival.
d. What is the difference between Intranets, Extranets and Internet?
ANS
An intranet is a private network within an organisation that resembles the Internet. Like the
public Internet, intranets use browsers, Web sites, and Web pages. Intranets typically provide
e-mail, mailing list, newsgroup, and FTP services accessible only to those within the
organisation.
An extranet is a private network that connects more than one organisation. Many
organisations use Internet technologies to allow suppliers and others limited access to their
networks. The purpose is to increase efficiency and reduce costs.
The Internet is the world’s largest network. It is like a giant highway that connects you to
millions other people and organizations located throughout the world. The internet is a huge
computer network available to nearly everyone with a microcomputer and a means to connect
to it. The internet encompasses the intranets and the extranets too.
UNIT 16
THE WORLD WIDE WEB
277
a. When was the WWW launched and where?
ANS
The Web also known as the WWW and the World Wide Web was introduced in 1992 at the
Center for European Nuclear Research (CERN) in Switzerland.
b. Explain the elements of a URL and the purpose of each.
ANS
Uniform Resource Locators (URLs): for browsers to connect to resources, the location or
addresses of the resources must be specified. These addresses are called URLs. The first part
presents the protocols (http://) used to connect to the resources while the second part presents
the domain name (noun). The last part of the domain name following the dot (.) is the domain
code (edu, ng).
The URL http:// www.noun.edu. ng connects your computer to a computer that provides
information about the National Open University of Nigeria, which is an educational
institution located in Nigeria.
c. What do you understand by the terms downloading and uploading?
ANS
Downloading is the process of receiving a file from another computer while Uploading is
the process of sending a file to another computer.
d. What are the three basic elements of an e-mail message?
ANS
A typical e-mail message has three basic elements: header, message and signature.
The Header appears first and include the following information:
– Addresses: addresses of the person sending, receiving, and, optionally anyone who is
to receive copies. E-mail addresses have basically three main parts: the user’s name,
the domain name and the domain code. For example [email protected], the
user’s name is dr_ahmed . The server providing services for Dr Ahmed is noun. The
domain code indicates that the provider is an educational institution in Nigeria.
–
Subject: A one line statement used to present the topic of the message. It also appears
when a person checks his/her mail box.
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–
Attachment: these are documents, photos or worksheets attached and send together
with the typed text in a mail. The file name usually appear on the attachment line if a
message contains an attachment.
The Message: this is the short note written in text format and usually straight to the point.
The Signature: the signature line provides additional information about the sender: name,
address, and telephone number.
UNIT 17
E-COMMERCE AND E-BUSINESS
a. What are the three types of e-commerce?
ANS
– B2B
– B2C
– C2C
b. What are the three basic payments for electronic payments?
ANS
– Check
– Credit
– E-Cash
c. What is the greatest challenge for e-commerce development?
ANS
Security- when it comes to electronic payments during transaction.
d. Among the three types of e-commerce, which is the fastest growing business?
ANS
B2C used by small, large, and start-up companies.
– e-banking
– e-trading
– e-retailing
UNIT 18
LAUNCHING INFORMATION
PROJECTS
a. What are ICT applications?
ANS
279
TECHNOLOGY
APPLICATIONS
ICT applications are design for person and enterprise use:
–
Designed for Shared Use
–
Designed for Sharing Data Resources
–
Designed to Connect a Variety of Users
–
Designed for Larger Size and Scope
b. What are enterprise systems projects?
ANS
These are projects designed for organizations to promote efficient and safe use of data across
the networks within their organizations.
– Systems Development.
–
Project Management
c. Who is the most valuable player in ICT application projects and what are his competent
skills?
ANS
The System Analyst is the key player in most IT application projects, because the System
Analyst follows the steps described in the system life cycle. Analyst plan and design new
systems or reorganize a company’s computer resources to best utilize them. Analysts follow
the systems development life cycle through all steps: preliminary investigation, analysis,
design, development, implementation, and maintenance.
• Professional Skills
– Problem Solving
– Outcome Thinking
– Creativity
– Meeting Skills
– Communication Skills
d. What is feasibility and whose responsibility is it in the IT department?
ANS
Feasibility is the measure of how beneficial or practical the development of an IT
project will be to an organization.
280
It is the dut y of a System Analyst to learn to think like a business manager and
conduct a feasibility analysis of the proposed system and make recommendations to
the management or users of the information system. Before carrying out the feasibility
study, project objectives and terms of reference must be identified.
UNIT 19
a. In a DFD chart what does the arrow stand for?
ANS
Dataflow Diagram (DFD): A chart showing the movement of data through a system.
The arrow shows the direction or data flow.
b. What are the data collection techniques the System Analyst use.
ANS
–
–
Interviews
Questionnaire:
–
Document Examination/Record Inspection
–
Observation
–
Sampling:
–
Dataflow Diagram (DFD)
c. State the two basic tools the System analyst used when creating an ICT project.
ANS
Computed-Aided Systems Engineering/Computer-Aided Software Engineering (CASE)is a set
of tools used in systems development to improve the consistency and quality of the system
while automating many of the most tedious and time-consuming systems tasks.
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Unified Modeling Language (UML) is a standard vehicle for visualizing, describing, and
documenting the details of an IT application. It is being used more extensively in industries to
assist in systems analysis.
d. What are the two types of interview conducted by a System Analyst during analysis?
ANS
•
Interviews
– Structured Interview: An interview in which the questions are prepared in
advance and each interviewee is asked the same set of questions.
– Unstructured Interview: An interview in which the questions may be prepared
in advance, but follow-up questions vary, depending on the interviewees’
background and answer.
UNIT 20
PROJECT MANAGEMENT
a. In the project management steps outline which is the most important? And why?
ANS
Defining the goals of the project:
Starting a project with the correct goal(s), make it easy to accomplish the goal(s).
b. Why do you need a backup plan(s) in project management?
ANS
Projects always involve a finite amount of uncertainty (risk) that may lead to problems and
surprises during the project. Dealing with surprises requires more time, energy, and money
than originally planned.
c. What do you consider to be the basic inputs in a project?
ANS
–
Goals
–
Team Staff
282
–
Money (N)
–
Time
–
Equipment
d. What are the don’t(s) in planning a project?
ANS
Do not underestimate the amount and type of resources required be realistic. This leads to
projects that run over budget and fall behind schedule. DO NOT attempt to do any of the
following:
–
–
–
Squeeze a project into a shorter time frame to please your boss
Cut corners to minimize resource requirements
Plan on a best-case basis, i.e. "If everything goes correctly, we will finish on time."
UUNIT 21
WEB BASED APPLICATION
a. What is the different between Web based application and personal/enterprise
applications?
ANS
Personal/Enterprise application programs are owned by individuals or organizations and
stored on their computer system’s hard disk. For the application to be used, a copy of the
program (or part of the program) is read into the computer system’s memory.
Web-based applications free users from owning and storing applications on their Computers.
They now use applications on the fly. Web based applications provide and ease to the high
cost of maintaining software and the ICT department of most organizations.
b. What are Heterogeneous Applications?
ANS
Heterogeneous Applications: May be written in different programming languages, run on
different types of computers, and use varying communications networks and transmission
methods
283
c. What are the basic Technologies of Web Services and their Principles?
ANS
XML, SOAP, UDDI and WSDI
–
Extensible Markup Language (XML) - is a set of rules for creating tags that describe
the layout and content of Web data.
–
Simple object access protocol (SOAP) - sometimes known as services oriented
Architectural Protocol. Protocol for invoking remote Web services objects using
XML
–
Universal Discover, Description and Integration (UDDI) - XML-based public
directory services that provides information about available Web services
–
Web Service description Language (WSDI) - Protocol that describe the capabilities
of a Web service object
d. What are the Advantages of XML?
ANS
–
–
–
–
–
–
UNIT 22
Web-based
Extensible
Computer and software platform independent
Facilitates end-to-end application integration
A public, license-free standard
Has widespread vendor support
INFORMATION SYSTEMS IN THE ENTERPRISE
a. What are the characteristics of the management information systems?
ANS
Characteristics (MIS)
–
Uses data captured and stored as a result of transaction processing
–
Reports data and information rather than details of transaction processing
–
Assist managers in situations, evaluating conditions, and determining what actions
need to be taken.
–
Supports recurring decisions
284
–
Provides information prespecified reports formats, either in print or on-screen.
b. What are the technologies used in the manufacturing industry?
ANS
The IT technologies are:
– Computer-Integrated Manufacturing (CIM)
– Manufacturing Cell
– Material Requirements Planning (MRP)
– Manufacturing Resource Planning (MRP III)
– Computer-Aided Manufacturing (CAM) Systems
– Flexible Manufacturing
– Concurrent Engineering
– Robot
– Comput er Vision System
c. Define value chain.
ANS
Value Chain is set of activities that are relevant to understanding the bases of cost and
potential sources of differentiation of a firm.
– Primary Value-Chain Activities
– Support Value-Chain Activities
d. What are the questions asked when creating a strategic role for an IS.?
ANS
To determine whether information technology can be developed to serve a strategic role,
ask the following five questions:
– Change the basis of competition?
– Build barriers to new entrants?
– Build in switching costs to customers?
– Strengthen a firm’s power in dealing with suppliers?
– Generate or serve as new products?
UNIT 23
ISSUES IN INFORMATION TECHNOLOGY
285
a. What are the sources of security breach
ANS
–
Employees
•
–
Identify Theft: Loss of personal identity through a security breach.
Computer Viruses

Virus: A hidden program that alters without the user’s knowledge, the way a
computer operates or that modifies the data and programs stored on the
computer.
–
Hacker and Crackers
• Gaining access to a system illegally for fun and challenge while crackers do it
for malicious purpose.
–
Organised Crime
 Counterfeiting and forgery.
–
Terrorist:
• Cyber terrorism: Terrorist attack on computer facilities in companies that rely
on IT to produce their services.
b. Differentiate between security and breaches
ANS
Security is the means of safeguarding and protecting an enterprise’s information technology
assets, that is by keeping away from criminals, natural hazards, and other threats.
Breach is a breakdown in security.
– Intrusion: Forced and unauthorized entry into a system.
–
Interception: Aimed at preventing the capture of data and information transmitted
over an enterprise network or other communications link.
c. What are the measures put in place to avoid software piracy?
ANS
Software Piracy is the making of illegal copies of software.
The measures are:
• Software Copyright Protection
286
– Copyright: Legal protection of original works against unauthorized use,
including duplication.
•
Copy Protection: A software protection scheme that defeats attempts to copy a
program or makes the copies software unreliable
•
Software Site Licensing
– Site License: An agreement under which a software purchaser pays a fee to
the manufacturer to make a specified number of copies of a particular
program.
d. What are the measures taken to ensure ICT service reliability?
ANS
The measures taken to ensuring it service reliability are:
– Fault-tolerant Computer: A computer designed with duplicate components to ensure
reliability.
– Uninterruptible Power Supply (UPS) System: A system that ensures the continued flow
of electricity when the primary source of power fails.
– Disaster Recovery Plan: A procedure for restoring data lost when a system stops
functioning.
– Off-site Backup Facility: A backup computer center located away from a company’s
main facility.
• Hot Site: A fully equipped backup computer center to which a company can
take its backup copies of data and software and resume processing.
• Cold Site: A backup facility outfitted with electrical power and environmental
controls so that it is ready for a company to install a computer system.
UNIT 24
CAREERS IN IT
a. Which fields are related in terms of hardware?
ANS
Computer Technician
287
Computer Technicians repair and install computer components and system.
Network Administrator
Network Administrators create and maintain networks.
b. Which IT positions are unique?
ANS
– Technical Writer
Technical Writers prepare instruction manuals, technical reports, and other scientific or
technical documents.
– Cryptographer
Cryptographers design, test, and perform research encryption procedures.
c. Which IT position requires knowledge in all fields?
ANS
System Analyst
System Analysts plan and design information system.
d. Which IT position is a top level position?
ANS
Information Systems Manager
Information Systems Managers oversee the work of programmers, computer specialists,
systems analysts, and other computer professionals.
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