college of education wvcst review center computer
WESTERN VISAYAS COLLEGE OF SCIENCE AND TECHNOLOGY
LA PAZ, ILOILO CITY
COLLEGE OF EDUCATION
WVCST REVIEW CENTER
By: Romy S. Lopez
Why Is Computer Literacy Important?
Computer literacy involves having knowledge and understanding of computers and their uses. As computers become more a part of everyday life, many people believe that computer literacy is vital to success.
What Is a Computer?
A computer is an electronic device, operating under the control of instructions stored in its own memory, that can accept data, process the data according to specified rules, produce results, and stores the results for future use.
Data – is a collection of unprocessed items, which can include text, numbers, images, audio, and video.
A word data is plural for datum. With respect to computers, however, it is accepted and common practice to use the word data in both the singular and plural context.
Information - is a processed data that conveys meaning and is useful to people.
Example: Employees name and address, hourly pay rate, and hours work worked all represents data.
The computer process the data to produce the payroll check (information)
Information Processing Cycle - Series of input, process, output, and storage activities performed by a computer.
Essential elements of Input Processing Cycle
1. Input – sample are the data’s entered by the user
2. Process – the instructions that the computer performs
3. Output – the information or the results
4. Storage – stores the result for future use
5. Communication – computers communication to other computers
Instructions – are the steps that tell the computer how to perform a particular task.
What Are the Components of a Computer?
The electric, electronic, and mechanical components of a computer, or hardware, include input devices, output devices, a system unit, storage devices, and communications devices. An input device allows you to enter data or instructions into a computer. An output device conveys information to one or more people. The system unit is a case that contains the electronic components of a computer that are used to process data. The circuitry of the system usually is part of or is connected to a circuit board called the motherboard. A storage device records and/or retrieves items to and from storage media. A communications device enables a computer to send and receive data, instructions, and information to and from one or more computers.
What are the two types of input?
Data – is a collection of unprocessed text, numbers, graphics, images, audio and video.
Instructions - are the steps that tell the computer how to perform a particular task.
Program – is a series of instructions that tells a computer what to do and how to do it.
Command – is an instruction that causes a program to perform a specific action.
User response – is an instruction a user issues by replying to a question displayed by a program
Input Device – is any hardware component that allows users to enter data and instructions into a computer.
1. Keyboard - It contains keys you press to enter data into the computer.
2. Mouse - Is a small handheld device. With the mouse, you control the movement of a small symbol on the screen, called the pointer, and you make the selections from the screen.
3. Microphone – allows a user to speak into the computer to enter data and instructions.
4. Scanner - converts printed materials (such as text and pictures) into a form the computer can use.
5. Digital Camera - you take pictures and then transfer the photographed images to the computer or printer instead of storing the images on traditional film.
6. PC Video Camera – is a digital video camera that allows users to create a movie or take still photographs electronically.
Output Device – is any type of hardware component that conveys information to one or more people.
Commonly used output device: display devices, printers, speakers and headsets, fax machines and fax modem, multifunction peripherals, data projectors and force-feedback joystick and wheels.
1. Printer – produces text and graphics on a physical medium such as paper.
2. Monitor - display text, graphics, and videos on a screen.
3. Speaker - you to hear music, voice and other audio (sounds)
SYSTEM UNIT - Two main components on the motherboard
1. Processor or CPU (Central Processing Unit) – is the electronic component that interprets and carries out the basic instructions that operate the computer.
What is the central processing unit (CPU)?
The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer.
Processor contains a two components, the control unit and arithmetic logic unit that works together to perform processing operations o
Control Unit – is the component of the processor that directs and coordinates most of the operations in the computer.
Arithmetic Logic Unit (ALU) – another component of the processor performs arithmetic, comparison, and other operations.
2. Memory - consists of electronic components that store instructions waiting to be executed and data needed by those instructions. Although some forms of memory are permanent, most memory keeps data and instructions temporarily, which mean its contents, are erased when the computer is shut off.
What is Memory?
Memory – consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processed data (information) o
Memory stores three basic categories of items
The operating system and other system software that control or maintain the computer and its devices.
Application programs that carry out a specific task such as word processing and resulting information
The data being processed by the application program and resulting information.
Bytes and Addressable Memory o
Byte (a character) – is the basic storage unit in memory. When the application program instructions and data are transferred to memory from storage device, the instructions and data exists as bytes.
Each byte resides temporarily in a location in memory that has an address.
Address – is a unique number that identifies the location of a byte in memory.
How is Memory measured?
Memory Sizes o
Kilobyte (KB or K) – is equal to exactly 1024 bytes.
Megabyte (MB) – is equal to approximately 1 million bytes o
Gigabyte (GB) – equals to approximately 1 billion bytes o
Terabyte (TB) – equals to approximately 1 trillion bytes.
KB or K
Approximate Number of Bytes
Exact Amount of
Approximate number of Pages or
Types of Memory
Volatile Memory – when the computers power off, it loses its content. (temporary)
Example: RAM (Random Access Memory) o
Nonvolatile Memory – does not lose its content when power is removed from the computer
Examples: ROM (Read Only Memory), flash memory, CMOS (Complimentary Metal
What is random access memory (RAM)?
Also called main memory.
Consist of memory chips that can be read from and written to by the processor and other devices.
When you turn on power to a computer, certain operating system files (such as the files that determine how the Windows XP desktop appears) load into RAM from a storage device such as hard disk. These files remain in RAM as long as the computer has continuous power. As additional programs and data are requested, they also load into RAM for storage.
The processor interprets and executes programs instructions while the program is in RAM.
How do computers represent data?
To understand fully the way a computer processes data, you should know how a computer processes data.
People communicate through speech by combining words into sentence. Human speech is analog because it uses a continuous (wave form) signals that vary in strength and quality.
Most computers are digital, they recognize only two discrete states: on and off. This is because computers are electronic devices powered by electricity, which has only two states: on and off.
The two digits, 0 and 1, easily can represent these two states. The digit 0 represents the electronic state of
off (absence of electronic charge). The digit 1 represents the electronic state of on (presence of an electronic charge).
When people count, they use the digits in the decimal system (0 through 9). The computer, by contrast, uses a binary system because it recognizes only two states. o
Binary system – is a number system that has just two unique digits, 0 and 1, called bits.
Bit – (a short for binary digit) is the smallest unit of data the computer can process.
What is read-only memory (ROM)?
Read-only Memory (ROM) – refers to the memory chips storing permanent data and instructions. The data on most ROM chips cannot be modified – hence, the name read-only.
ROM is nonvolatile, which means its contents are not lost when power is removed from the computer. In addition to computers, many devices contain ROM chips. For example, ROM chips in printers contain data for fonts.
Storage Media – It is where a computer keeps data, instructions, and information. Example of storage media are floppy disks, Zip disks, USB Flash drives, hard disks, CDs, DVDs, and memory cards.
Storage Device - Records (writes) and/or retrieves (reads) items to and from storage media. Drives and reader / writers, which are types of storage devices, accept a specific kind of storage media. It often functions as a source of input because they transfer items from storage to memory.
Examples: a. CD Drive (storage device) accepts a CD (storage media).
b. Floppy drive accepts a floppy disk c. Zip drive accepts a Zip disk
Floppy disk – consists of a thin, circular, flexible disk enclosed in a square-shaped plastic shell that is inserted in and removed from a floppy disk drive (FDD). A typical floppy disk stores up to about 1.4 million characters.
Zip disk - looks similar to a floppy disk but has much greater storage capabilities – up to about 750 million characters. You insert zip disks in and remove them from Zip drives.
USB (Universal Serial Bus) flash drive - is a portable storage device that has much more storage capacity than a floppy disk but is small and lightweight enough to be transported on a keychain or in a pocket. You plug a USB
Flash Drive in a special, easily accessible opening on the computer (the USB port).
Hard Disk - provides much greater storage capacity than a floppy disk, zip disk, or USB flash drive. The average hard disk can hold more than 80 billion characters. Hard disk is enclosed in an airtight, sealed case. Although some are removable, most are housed inside the system unit
Compact Disc (CD) - is a flat, round, portable metal disc with a plastic coating.
Type of Compact Disc
1. CD-ROM - which you can access using most CD and DVD drives.
2. DVD-ROM – some of which have enough storage capacity to store two full-length movies. To use a DVD-
ROM you need a DVD drive. DVD (also known as "Digital Versatile Disc" or "Digital Video Disc")
What Are the Categories of Computers?
Industry experts typically classify computers in six categories: personal computers, mobile computers and mobile devices, midrange servers, mainframes, supercomputers, and embedded computers.
A personal computer is a computer that can perform all of its input, processing, output, and storage activities by itself.
Two popular styles of personal computers o
PC Compatible – refers to any personal computer based on the original IBM personal computer design. Companies such as Dell, Gateway, Hewlett-Packard, and Toshiba sell PC-Compatible computers and uses a Windows operating system o
Apple – use a Macintosh operating system (Mac OS)
Two types of Personal Computer o
Desktop computers – is designed so the system unit, input devices, output devices and any other devices fit entirely on or under a desk or table.
Some desktop computers functions as a server on a network and cost much more than the basic desktop computer.
Workstation – another expensive, powerful desktop computer which is geared for work that requires intense calculations and graphic capabilities.
An architect uses a workstation to design building and home. A graphic artist uses a workstation to create computer – animated special effects for full length motion pictures and video games.
Notebook computers – also called a laptop computer, is a portable, personal computer designed to fit on your lap.
They are thin and lightweight, yet they can be as powerful as the average desktop computer.
And more expensive than desktop computers with equal capabilities.
The keyboard is on the top of the system unit, and the monitor attaches to the system unit with hinges.
Weigh on average between 2.5 and 9 pounds, which allow users easily to transport the computer from place to place.
Can operate on batteries or a power supply or both.
Tablet PC is a special type of notebook computer that allows you to write or draw on the screen using a digital pen.
With a digital pen, users write or draw by pressing the pen on the screen, and issue instruction to the Tablet PC by tapping on the screen.
A mobile computer is a personal computer that you can carry from place to place, and a mobile device is a computing device small enough to hold in your hand.
Usually do not have disk drive o Four popular types of mobile devices
- Handheld computers – (sometimes a handtop computer) is a computer small enough to fit on one hand.
Screens on handheld computers are small
- PDAs (Personal Digital Assistant) – is one of the most popular lightweight mobile devices in uses today.
Provides organizer functions such as a calendar, appointment book, address book, calculator and notepad.
- Smart phones – is an internet enabled telephone that usually also provides PDA capabilities o
Allows you to send and receive e-mail messages and access the web.
- Smart watches - is an internet enabled watch. In addition to basic timekeeping capabilities, a smart watch automatically adjust time zone changes, stores personal messages, reminds you of appointments, and wirelessly accesses news, weather, sports and stocks.
A midrange server is a more powerful and larger computer that typically supports several hundred and sometimes up to a few thousand connected computers at the same time.
Typically support several hundred and sometimes up to a few thousand connected computers at the same time
A mainframe is a large, expensive, powerful computer that can handle hundreds or thousands of connected users simultaneously and can store tremendous amounts of data, instructions, and information.
Store tremendous amounts of data, instructions, and information.
Every major corporation uses mainframes for business activities
A supercomputer is the fastest, most powerful, and most expensive computer and is used for applications requiring complex, sophisticated mathematical calculations.
The fastest supercomputers are capable of processing more than 100 trillion instructions in a single
With weights that exceed 100 tons, these computers can store 20,000 times the data and information of an average desktop computer.
An embedded computer is a special-purpose computer that functions as a computer in a larger product.
Embedded computers are everywhere – at home, in your car, and at work.
How Is System Software Different from Application Software?
Software, also called a program, is a series of instructions that tells the computer what to do and how to do it.
You interact with a program through its user interface which controls how you enter data and instructions and how information is displayed on the screen.
GUI – Graphical User Interface, allows you to interact with the software using text, graphics, and visual images such as icons.
Icon – is a miniature image that represents a program, an instruction, or some other object.
Two categories of software
System software consists of the programs that control or maintain the operations of a computer and its devices. It serves as the interface between the user, the application software, and the computer’s hardware.
Two types of system software
o Operating system - which coordinates activities among computer hardware devices.
Example: Microsoft Windows XP, Ubunto, Red Hat Linux, Mac OS o Utility programs - which perform maintenance-type tasks usually related to a computer, its devices, or its programs. (e.g. utility programs for managing disk drive, printers, and other devices)
Application software consists of programs that perform specific tasks for users. Popular application software includes Web browsers, word processing software, spreadsheet software, database software, and presentation graphics software.
Other types of application software
- Personal Information Management
- Note taking
- Project management accounting
- Computer aided design
- Desktop publishing
- Paint/image editing
- Audio and video editing
- Education reference
- Web page authoring
- Multimedia authoring
- Personal finance
- Tax preparation
- Home design/landscaping
- Entertainment (e.g. games or simulation)
Installing – is the process of setting up software to work with the computer, printer and other hardware components.
What Are the Advantages and Disadvantages of Using Computers?
Advantages of using Computers
1. Speed – computer operations occur through electronic circuits. When data, instructions, and information flow along these circuits, they travel at incredibly fast speeds. Many computers process billions or trillions of operations in a single second. Processing involves computing (adding, subtracting, multiplying, dividing), sorting (alphabetizing), organizing, formatting, checking spelling and grammar, charting, displaying pictures, recording audio clips, playing music, and showing a movie.
2. Reliability – The electronic components in modern computers are dependable and reliable because they rarely break or fail.
3. Consistency – Given the same input and processes, a computer will produce the same results – consistently.
Computes generate error – free results, provided the input is correct and the instructions work.
A computing phrase – known as garbage in, garbage out – points out that the accuracy of a computer’s output depends on the accuracy of the input.
4. Storage – A computer can transfer data quickly from a storage to memory, process it, and then store it again for future use. Many computers store enormous amounts of data and make this data available for processing anytime it is needed.
5. Communications – Most computers today can communicate with other computers, often wirelessly. Computers with this capability can share any of the four information processing cycle operations – input, process, output, and storage – with another computer or a user.
Disadvantages of Using Computers
1. Violation of Privacy – Nearly every life event is stored in a computer somewhere…in medical records, credit reports, tax records, etc. It is crucial that personal and confidential records be protected properly. In many instances, where these records were not properly protected, individuals have found their privacy violated and identities stolen.
2. Impact on Labor Force – Although computers have improved productivity in many ways and created an entire industry with hundreds of thousands of new jobs, the skills of millions employees have been replaced by computers.
Thus, it is crucial that workers keep their education up-to-date. A separate impact on the labor force is that some companies are outsourcing jobs to foreign countries instead of keeping their homeland labor force employed.
3. Health Risks – Prolonged or improper computer use can lead to injuries or disorders of the hand, wrists, elbows, eyes, neck, and back. Computer users can protect themselves from these health risks through proper workplace design, good posture while at the computer, and appropriately space work breaks.
4. Impact on Environment – Computer manufacturing processes and computer waste are depleting natural resources and polluting the environment. The amount of the resources required to manufacture a personal computer equals that a mid sized of a car. When computers are discarded in landfills, they release toxic materials and potentially dangerous levels of lead, mercury, and flame retardants. Strategies that can help protect the environment include recycling, regulating manufacturing processes, extending the life of computers, and immediately donating replaced computers.
What Are the Elements of an Information System?
Information must be accurate, organized, timely, accessible, useful and cost-effective to produce.
An information system combines hardware, software, data, people, and procedures to produce timely and useful information.
The hardware must be reliable and capable of handling the expected workload
The software must be developed carefully and tested thoroughly
The data entered into the computer must be accurate
Most companies with mid-sized and large computers have an IT (Information Technology) department.
Staff in the IT department should be skilled and up-to-date on the latest technology
IT staff should also train users so they can understand how to use the computer properly.
IT applications should have readily available documented procedures that address operating the computer and using its application
What Are the Types of Computer Users?
Computer users can be separated into five categories: home users, small office/home office users, mobile users, large business users, and power users.
A home user is a family member who uses a computer for a variety of reasons, such as budgeting and personal financial management, Web access, communications, and entertainment.
On the internet, home users access a huge amount of information, take college classes, pay bills, management investments, shop, listen to the radio, watch movies, read books, play games, file taxes and make airline reservations.
A small office/home office (SOHO) user is a small company or self-employed individual who works from home.
SOHO users access the Web to look up information and use basic business software and sometimes industry-specific software.
Websites advertise products and services and may provide a means of taking orders o
Small business web sites sometimes use a web cam, which is a video camera that
• displays its output on a web page. A web cam allows SOHO users to show the world a live view of some aspect of their business.
Mobile users are employees and students who work on a computer while away from a main office or school.
Examples of mobile users o
Sale representatives, real estate agents, insurance agents, meter readers, package delivery people, journalist, consultants and students.
A power user uses a workstation or other powerful computer to work with industry-specific software.
Example of power users
- Desktop publishers
- Graphic artist
Often work with multimedia, combining text, graphics, audio and video into one application. These users need computers with extremely fast processors because of the nature of their work.
A large business user works in a company with many employees and uses a computer and computer network to process high volumes of transactions.
Enterprise computing – to refer to the huge network of computers that meet their diverse o computing needs.
The network facilitates communication among employees at all locations o o
Users access the network of midrange servers or mainframes through desktop computers,
PDAs, and smart phones.
Large businesses use computers and the network to process high volumes of transactions in a single day
What Is the Purpose of a Network?
Sharing resources saves time, money and effort
A network is a collection of computers and devices connected together via communications devices and transmission media. When a computer connects to a network, it is online.
Networks allow computers to share resources, such as hardware, software, data, and information.
In many networks, one or more computer acts as a server.
Server – control access to the resources on the network.
Computer that other computers access: A computer in a network that stores application programs and data files accessed by the other computers in the network o
Client – the other computers on the network and the computer request resources from the server.
Computer that requests data: a computer program used to contact and obtain data from a program on another computer, often one linked on a network. A World Wide Web browser is a specific kind of client.
Difference between the client and the server is that: server has more power, more storage space, and expanded
Topology in Network Design
In computer networking, topology refers to the layout of connected devices.
Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network.
Network topologies are categorized into the following basic types:
Bus networks use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.
Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
How Are the Internet and World Wide Web Used?
The Internet is a worldwide collection of networks that connects millions of businesses, government agencies, educational institutions, and individuals.
People use the Internet to:
• communicate with and meet other people
Access news and information
• shop for goods and services
• bank and invest
• take classes, and
• access sources of entertainment and leisure (e.g. online games, music, videos, books, and magazines).
People connect to the internet to exchange information with others around the world.
E-mail allows you to send messages to other users.
Access providers – a business, offer users and companies access to the internet free or for fee. By subscribing to an access provider, you can use your computer and a communication device, such as modem, to connect to the many services of the internet.
Web (World Wide Web) - is a global library of documents containing information that is available to anyone connected to the Internet. It contains billions of documents called Web pages.
Web pages – can contain text, graphics, audio, and video and often have built-in connections, or links, to other documents, graphics, other Web pages, or Web sites.
Website - is a collection of related Web pages.
Photo sharing community – is a website that allows users to create an online photo album and store their electronic photographs
What Is the History of the Internet?
Internet - is a worldwide collection of networks that links millions of businesses, government agencies, educational institutions, and individuals.
The Internet has its roots in a networking project started by the Pentagon’s Advanced Research Projects Agency (ARPA), an agency of the U.S. Department of Defense.
ARPA’s goal was to build a network that.
1. Allowed scientist at different physical locations to share information and work together on military and scientific and scientific projects.
2. Could function even if part of the network were disabled or destroyed by a disaster such as a nuclear attack.
Who controls the Internet?
No one - it is a public, cooperative, and independent network
Several organizations set standards
World Wide Web Consortium (W3C)
Oversees research, sets standards and guidelines
Tim Berners-Lee, director
Internet-related research and development project
Develops and tests advanced Internet technologies
Their goal is to change the current Internet’s inefficiencies, such as relieving bottlenecks (traffic constriction or delay I progress).
How Can You Access and Connect to the Internet?
Dial-up access - uses a modem in the computer and a standard telephone line to connect to the internet. This type of access is an easy and inexpensive way for users to connect to the Internet, however, is a slow-speed technology.
Broadband internet access – a higher speed of internet connection.
DSL (digital subscribers line) – is a technology that provides high-speed internet connections using regular copper telephone lines.
A cable modem – allows access to high-speed internet services through the cable television network.
Fixed wireless – a high speed internet services use an antenna on your house or business to communicate with a tower location via radio signals.
What Is an IP Address?
An IP address (Internet Protocol address) is a number that uniquely identifies each computer or device connected to the Internet. The Internet relies on IP addresses to send data to computers at specific locations.
The IP address usually consists of four groups of numbers, each separated by a period. The number in each group is between 0 – 255.
For example: the numbers 184.108.40.206 are an IP address. In general, the first portion of each IP address identifies the network and the last portion identifies the specific computer.
Domain name system (DNS) – is the method that the internet uses to store domain names and their corresponding
DNS server – is an Internet server that usually is associated with an access provider. When you specify a domain name, the DNS server translates the domain name to its associated IP address so the data can be routed to the correct computer.
What Are the Components of a Web Address?
The World Wide Web (WWW), or Web, consists of a worldwide collection of electronic documents. Each electronic document is called a Web page, which can contain text, graphics, audio (sound), and video.
Type of web pages
1. static (fixed) – visitors to a static webpage all see the same content
2. dynamic (changing) – visitors can customize some or all of the viewed contents such as desired stock quotes, weather for a region, or ticket availability for flights.
Website – is a collection of related web pages and associated items, such as documents and pictures, stored on a web server.
Web server – is a computer that delivers requested web pages to your computer. The same web server can store multiple websites. For example, many access providers grant their subscribers free storage space on a web server for personal or company websites.
What Is the Purpose of a Web Browser?
A Web browser, or browser, is application software that allows users to access and view Web pages. When you type a Web address in the Address box of a browser window, a computer called a Web server delivers the requested Web page to your computer. Most Web pages contain links. A link is a built-in connection that, when clicked, displays a related Web page or part of a Web page.
Most widely used web browsers
1. Internet explorer
Home page – refers to the first page that the web site displays
Microbrowser – a special type of browser which is designed for internet-enabled mobile devices such as PDAs and smart phones, which is designed for their small screens and limited computing power.
Downloading is the process of a computer receiving information, such as a web page, from a server on the internet.
A URL (Uniform Resource Locator), or Web address, is a unique address for a Web page..
Example: the home page for the San Diego Zoo Website http://www.sandiegozoo.org
A Web address consists of a protocol, a domain name, and sometimes the path to a specific Web page or location on a Web page. Many Web page addresses begin with http://.
The http, which stands for Hypertext Transfer Protocol – is a set of rules that defines how pages transfer on the internet.
protocol domain name path Web page name
Navigating Web Pages
Link – short for hyperlink is a built in connection to another related web page or part of the web page.
Surfing the web – refer to the activity of using links to explore the Web.
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