Part-I - CPoint Computer Center

Part-I - CPoint Computer Center
Syllabus of Computer Fundamental
1. Introduction of Computer
What is computer, functions, different units of Computer, Data , Information & Process.
Page No.
2. History & Generation of computer
Evolution of Computer, Generation of Computer
3. Memory Of Computer
Internal Memory (RAM , ROM, Register, Cache Memory ) ,
Secondary Memory (Floppy Disk, Hard Disk , Optical Disk )
4. Classification of Computer
5. I/O Device
Input device & Output Device
6. Software & Languages
7. Virus
8. Networking & Internet
9. Concept of OS
10. Ms-Dos
11. Windows XP
Computer Fundamental ,Ms-Dos, Windows XP/7/8
[ These notes are based on the author’s personal interpretation of texts on
the subject in various books, journals and web-sites. These notes are not a
substitute for any text book prescribed by the university or the institution.
This is not the final version of the notes and it can be altered at any time by
the author before, during and after his classes, if needed..]
"C" POINT Research & Development Team
Introduction to Data Processing
What is Data?
Data is a collection of facts, figures, statistics which can be processed to produce meaningful information. In
a business environment. Data can be the number of hours worked. names of employees. Stock inventory
levels details of purchases made, expense statements, or employee pay details. In the educational
environment data can be names of students, marks obtained their rill number and so on.
Data is input raw facts which may or may not have meaning.
What is processing?
Processing is the manipulation of the letters, numbers, or graphic symbols that constitute data. Data is
collected, captured, sifted, rearranged, sorted in a sequence, stored, retrieved, formatted and sent to various
persons who need the information.
Doing of any task or any operation is known as Process. It may collection of instruction or a program, which
operate on the data in such a way that to make it meaning full
Processing includes –
addition, subtraction, multiplication, division
equal to greater than, less than, zero, positive, negative
branching to a different path depending on a condition
the sequence or flow of step to be followed to get the desired result
Processing is not restricted to numbers. Correcting errors in a document, aligning the next to margin specific
etc. Using computers is also processing.
What is Information?
Information is processed data. It refers to facts, figures or statistics that have meaning. Although data and
information are technically different they are often used interchangeably. The reason is because whether a
particular item or statistic is information, depends not only upon its content value but also upon the individual
to whom it is given. Thus a particular fact may be information to an individual (Process) but the same may
be data to another individual (process). The example given below illustrates this. The meaningful form of
data generally called Information, which is generated after processing. The output of system is known as
To an individual student taking up an examination the marks scored by him in individual papers form
the “data” and the average marks scored by him on which his results forms the “ Information”. However, for
the teacher the average marks scored by each individual form the “data” from which the class average is
calculated which is the “information” generated. Neither the examination marks nor the class average would
be “information” to a student not enrolled in the class. This example also shows that information generated
from one process can become the data or input for another process.
Input section: - it is the initial section of the computer system through which data & instruction can be
entered to the computer. It consists the set of electronics devices like keyboard, mouse, MICR, OMR, OCR
Process section: - it is the central section of the computer. It manipulates the data in such a way that make
it meaningful form. Process is defined as the doing of any task or operation is known as process.
Output Section: - it is the last section of the computer system where data comes out in form information.
This section consists of set of electronics devices like Monitor, Printer, and Plotter.
Why use a computer?
Organisation invariably large volumes of data. Processing this data tends to be a very tedious and time
consuming task Computers are ideally suited for repetitive tasks. They are accurate, versatile and can
handle many different applications. By computerizing repetitive tasks, an organisation can release personal
for more productive tasks and ensure accurate and quick processing of data.
What is a Computer? (Definition)
Computer is an electronic device, which can process any kind of data either arithmetically or logically
according to user‟s instructions.
It is called electronics device because it made up by using the electronic components (diode, transistor, IC),,
which are developed by using semi-conductor elements. The flow of electron in a peace of semi conductor is
known as electronics.
Computer can process numbers, symbols, characters, graphics, sound etc., so it can work on different types
of data.
Whereas calculator is a electronic device which can process only the digits and can perform arithmetical
operations only but computer performs both arithmetical and logical operations.
All mathematical operations are known as the Arithmetical operation and the conditional based operation
which evaluates true (yes) or false (no) known as the logical operation.
Computer is a device which can not do anything by it self. It have no decision making power as like human
being. It always performs the task and operation according to the instructions which are given by the user.
It can be defined as an electronic device with the ability
Accept data supplied by the user
Input, store and execute instructions
Perform mathematical and logical operations
Output results according to user requirements
Anatomy of a Computer System
A system is a set of components that works
together to accomplish one or more common
goals. A computer system can be viewed as a
System of three major components:
Computer hardware – this includes the
computer equipment that is the mechanical, electrical and electronic parts of the system.
Computer software – programs that instruct a computer how to process the data and generate
required information.
Computer personal – people who operate data for computerized input, developing computer
programs, monitoring computer operations and distributed the output. There are also end users who
use computer resources.
A computer system functions effectively only when all three components perform their assigned tasks. The
failure of any one component of the systems leads to the failure of the systems as whole.
Functional Components of a computer
There are five functional units of the computer system, 1. Input, 2.memory, 3.control unit, 4.ALU,
5.output. The hardware of any computer system can be broadly classified into the central processing Unit
(CPU) and Peripherals.
Central Processing Unit
The heart of the computer is called the CPU or processor. The CPU performs:
Arithmetic operations ( add, subtract, multiply, divide)
Logic operations (logical comparisons)
Input –output operations ( accepting data to be processed, generating the output or results of
Internal data movements (moving data between various parts of storage)
Data manipulation ( accepting data, sorting it, processing it, generating the required information)
To perform these various operations the CPU has various components
Arithmetic –logic unit (ALU)
Control Unit (CU)
Control Section
Memory Unit
Primary Storage
Input Device
(Key Board,
Mouse, Disk)
Program Storage
Working Storage
Output Device
Printer , Disk)
The Control Unit coordinates the operations of the hardware. It also coordinates the flow and execution of
data and instructions that are fed into the memory or main storage via the CPU. The CU functions in a fetch
–execute cycle. It fetches the instructions and data from the memory unit, decodes them and sends them to
the Arithmetic Logic unit (ALU). The output from the ALU is fetched by the control unit and sent to various
parts of the computer. It generates various control signals to controls the functional units. It acts like carrier
to carry the signal from one unit to another.
The Arithmetic Logic Unit (ALU) performs the actual calculations (addition, subtraction, division, and
multiplication) and final results ready for output. The data and instructions are passed from the main store
into ALU, or to and from the storage devices under the control of the CU. All instructions or data are stored
in the memory unit before being used by the ALU, or the CU. The main store is divided into a number of
storage locations. These can be accessed by a unique number or “address”.
The control unit and internal storage are linked together by sets of parallel electrical conducting lines called
buses. The buses that carry data buses. To retrieve data from memory it is necessary to identify the address
in main memory. The address is carried by the memory frequency of a PC clock is 4.77 MHz.
The frequency with which the processor executes instruction is called its clock speed. The frequency is
measured in megahertz (MHz). The minimum frequency of a PC clock is 4.77 MHz.
Peripheral Devices
The peripheral devices can be classified as input devices, output devices and backing storage devices.
The input devices allow can be user to get data into the machine. A large range of input devices is available.
e.g. keyboard, mouse.
Output devices are peripheral used to output results to the user. They include printers, Plotters, and VDU‟s
(Visual Display Units).
Backing storage devices or the secondary or the storage devices are mainly hard disk, disk packs, floppy
disks, and tapes used to store data and programs permanently.
Evolution of computer took place over thousands of years and finally we reached the modern age of
computers. The evolution process is significantly characterized by the following developments.
It is the first mathematical device developed for arithmetic computations. It was invented by Chinese in 3000
BC. It consists of a set of wires with mounted beads. This was used for addition and subtraction operations.
John Napier, the Scottish mathematician, devised a set of rods for use in calculations involving
multiplication. These rods were carved from bones and, therefore, called Napier‟s bones.
After abacus famous mathematician Blaise Pascal developed an arithmetic machine in 1642. It has toothed
wheels for units, tens, hundreds, thousands etc. Positions. Each wheel moves for units of that position of
the numbers. It is similar in functioning to that of odometer of motor vehicles. Addition and subtraction
operations were possible.
In 1671, Leibnitz, the German mathematician invented the first calculator for multiplication. It performed all
the four basic arithmetic operation addition, substractation, multiplication & division.
Charles Babbage of UK devised a machine called Analytical Engine in 1833 which could perform arithmetic
operations and store the data .This was a mechanical general purpose computer.
In 1880, Dr.Herman Hollerith of USA developed punched card machine to process census data. The data
was punched in cards in coded form. The card is placed on a metallic plate. Wired brush moves on the card
and makes contact with the plate in the punched holes and generates electrical pulses. This was very much
popular for data processing work.
In 1943 saw the milestone; with the development of Electronic Numeric Integrator and calculator (ENIAC) in
USA. It had nearly 18000 vacuum tubes, 70000 registers and 10000 capacitors. The weight was
approximately 27 tones. It needed Air conditioning. The failure of vacuum type was very frequent. This was
the first electronic calculating machine.
Earlier machine did not have the facility of storing instructions in memory .Von Neumann, for the first time
introduced the concept of stored program in memory. Present Days computers are based on this concept
and hence the architecture. Neumann is also sometimes referred as father of modern computers. The
machine called EDSAC (Electronic Delayed Storage Automatic computer) was developed in 1949 and was
the first digital computer to have stored program concept.
UNIVAC (Universal Automatic Computer) was first commercially available computer in 1951. It was used for
census work in USA. It had both numeric and alphabetic data processing.
The development of computer is classified into different generations depending upon the device technology,
Architecture, operational mode, Devices being used, speed etc. Each generation is considered to have
about 10 years time span.
First Generation computers were marked by use of vacuum tubes. Electrostatic tubes or mercury delay lines
were used for storage. Punched card was common input media. Programs were written in machine level
language ENIAC, EDVAC, UNIVAC were some popular computers. These computers suffer from the
drawbacks like large size, slow speed, heavy heat generation, higher rate of failures, Air-conditioning
requirement, high power consumption.
Second generation computers were marked by use of transaction in place of vacuum tubes. Use of
transistor reduces the size and cost. It also requires less power and less heat is generated. Reliability is also
high. Examples are IBM-1400,
IBM-7000, CDC-1604 etc. High level languages like FORTRAN, COBOL, and ALGOL were used for
programming. Magnetic Disk, magnetic core were used for storage.
Third generation computers were marked by use of integrated circuits (IC). An IC is a chip containing a
number of registers, transistors and capacitors. Size becomes still smaller and speed becomes faster, so
also less expensive. Examples are IBM-360. ICL-1900, Honey well 6000. In addition to higher version of
FORTRAN and COBOL new languages like BASIC, PASCAL, PL/I were used. Semi conductor memory is
Fourth generation computers were marked by use of LSI and VLSI techniques and also microprocessor. The
development in the field of IC technology LSI and VLSI technology came into being. Development of
microprocessor also took place. These are characterized by smaller size, lower cost, faster speed and
higher reliability. User friendly software was also used in these computers. Floppy Disks, Optical Disks are
used in these computers.
FIFTH GENERATION(1980- Till date)
The fifth generation computers are under development. These computers are characterized by extensive
use of parallel processing and presence of Artificial intelligence. Capability and power wise it will be very
much effective. It will have special features for NLP and Image Processing.
Memory is the storage area where data and programs are stored for the future use. Its stores the information
in form of binary digits 0‟sand 1‟s memory location is a binary cell which is addressable memory capacity
give the information about the amount of data and information can be stored.
Memory in computer is used for the following purposes.
 Store program and data during execution.
 Store Result of execution.
 Store Program and data for future reference.
The memory is classified in hierarchical structure as follows:
1:-Dynamic ram
2:-Static ram
Some memory is used to store the data and information for the temporary period. That means its contains
data and information as long as power is switched on or processing is going on. This memory is used for the
immediate processing or accessing it can contain limited amount of data or information temporary memory
Some memory is used as a permanent memory. It contains the data or information for the permanent period.
Some pre-loaded and some R/W memory (secondary).
In both the memories data or information‟s are recorded inform of binary bit.(0,1).
2 Nibble is 1 byte.
1 Nibble = 4 Bits (smallest unit)
2 Nibble = 8 Bits = 1 Byte
1024 Bytes = 1 Kilo Bytes
1024 Kilo Bytes = 1 Mega Byte
1024 Mega Bytes = 1 Giga Byte
Units of Memory
Computer system read signal in form of pulse and no pulse. Pulse
represent to ON that is 1 and no pulse represent to OFF that is 0. Each
digit 0/1 is know as bit(Binary Digit). A group of 4 (four) bits is know as 1
8 bits is known as 1 byte. 1 byte refers to a group of bits which represents to a single alpha numeric or
special character.
According to the using of memory it is divided into two types.
1Internal memory
2Secondary Memory ( Backing Storage Device)
Internal MemoryThe memory which is used as a internal part of the CPU. These memories are very
RAM- (Random Access Memory) it is a chip which consists data or information for the temporary period. It
is collect cells or empty locations. Each and every location having a unique number known as location or
memory address. It is purely temporary memory. It stores the data or information as long as computer is
switched on. After switch off the computer every thing will be vanished. It is power dependent volatile
memory. It uses as the main memory of the computer system. It contains both data and program. From this
memory the data and program starts execution. CPU process those data / instruction which are in RAM. It is
called as Random Access Memory Because CPU access the location / cells in a random order that means
CPU access any cell at any time. Both reading and writing operation is possible in this memory.
It is also called primary Memory because when the data/instruction being keyed that immediately
onto this memory. Then the future operation will start from this memory.
There are two types of RAM
Dynamic Ram
Static Ram
Dynamic Ram- In dynamic Ram data/information are stored as a light density. That means with in a small
volume and large amounts of data or information‟s are stored. In dynamic RAM data/information are stored
inform of changes and the change having general tendency to leak. So data are unstable in this memory. To
make the data stable an additional circuit is required. Which refresh the change at every moment. This
memory used as primary or main memory of the computer.
Static RamIt provides less density. It contains the data inform of 0‟s and 1‟s so data are more stable in
this memory. No any additional circuit is required to refresh the data. This memory is expensive that the
dynamic memory. This memory used as a cache memory in computer.
ROM (Read only Memory)It is pre-loaded chip. It contains a program, which are loads on this memory
at time o manufacturing. That program is known as BIOS.( Basic Input output system program). It is a
permanent memory. It does not depend on the power. After switched off the system the program resides on
this chip. It is non-volatile memory. It is a write-protected memory. Data/information can be stored on to this
memory only reading operation can be possible.
There are various types of ROM chips are used PROM, EPROM, EEPROM, EAPROM etc.
PROM- (Programmable Read only Memory) It is a pre-loaded memory. Which contains a program and it
loads on to the memory at the time of manufacturing. It can not be re-write or it can not be erasable.
EPROMErasable read only memory. The program, which loads on to this memory that, can be
erased by exposing the chip on to ultraviolet ray. It can be re-write. A new program can be load on to this
EEPROMElectrical erasable prog. Read only memory. It can be erased by the electrical pulse instead
of exposing the chip on Ultra-violet ray.
This memory is in built in the CPU. This consists o several electronic registers. CPU uses this to carry out its
various operations. A register is nothing but a group of binary cells each capable of holding one bit .
Register with n cells can store n bits of information. Size of the Register is called the world length, it can
handle. Numbers of registers in CPU vary from computer to computer. But there are some important
registers, which every CPU must have. They are Accumulator, PC, MAR< MBR etc. The amount of this
memory is very small. But this is the fastest of all kind of memory.
This is again very fast memory but put outside the CPU. The size of this memory is also less. This is used
for storing frequently used program and data. As the volume of main memory is relatively more the access
speed is small. To compensate the loss in speed in referring main memory, the cache memory is used.
It is the intermediate memory, which use in between main memory and cpu. It manages the timing and
speed of the cpu cache memory consists few number of slots, Each slot can hold a block of main memory.
CPU reads the words from cache for immediate.
This is the memory where program is stored for execution by CPU. This memory directly communication
with CPU. Unless program and data are loaded into this memory, execution is not possible. It is volatile in
nature. This means that whenever power goes out the contents of this memory will be lost. So in order to
save the contents from loss it is to be transferred to secondary memory. It consists of semi-conductor
memory. Access speed is higher than Auxiliary memory. Amount of memory is limited by the CPU used. It is
also known as primary memory because when data being entered that immediately stored in this memory.
As main memory is of limited capacity and size it is not possible to store everything in main memory. To
supplement the necessity of more memory, Auxiliary memory is used. This is non volatile memory. It
consists of magnetic or optical materials. It is of unlimited capacity. Both read and write operation is
possible. Access speed is very less. It stores data permanently until the user erases it. This also known as
secondary memory or back up memory. Data or program stored in auxiliary memory is to be loaded into
main memory for execution. Examples of this memory are magnetic Disk, Magnetic Tape etc.
Difference between Main Memory and Auxiliary Memory:
Devices that provide backup storage are called Auxiliary memory. Magnetic disk and tapes are the
commonly used auxiliary memory devices.
Access Time
The average time required to reach a storage location in memory and obtain its contents is called the access
time. The Access time for magnetic disk and tapes consists of seeks time plus transfer time.
Seek Time
The time required to position the read-write head to a location.
A magnetic disk is a circular plate made of metal or plastic coated with magnetized material often both sides
of the disk are used and several disks may be stacked on one spindle with read/write head available on
each surface. All disks rotate together at high speed and are not stopped or started for access purpose.
Bits are stored on the magnetized surface in spots along concentric called tracks. The tracks are
commonly divided into sections called sectors. The minimum quantity of information, which can be
transferred, is a sector.
Some units use a single read/write head for each surface of the disk. In this type of Unit, the track
address bits are used for moving the head into the specified track position, before reading or writing. In other
disk system separate read /write heads are provided bit selects a particular track. This type of Unit is more
Address bits that specify the disk number, the disk surface, the sector number and the track
within the sector address a disk system. After the read/write heads are positioned in the specified track, the
system has to wait unit the rotating disk reaches the specified sector under the read/write head. Then the
beginning of the sector is reached, the data is transferred very fast. Disk may have multiple heads and
simultaneous transfer of bits from several tracks is possible at the same time. A track in a given sector near
the circumference is longer than a track near the centre of the disk. If the bits are recorded with equal
density, some tracks will contain more recorded bits than others. To make all the records in a sector of equal
length, some disk use a variable recording density, with high density on tracks near the center than on
tracks near the circumference. This equalizes the number of bits on all tracks of a given sector.
It is one popular form of Auxiliary storage. It consists of a disk of plastic material with magnetic oxide coated
on both sides. The disk is enclosed in a rectangle plastic jacket. The disk size available in 51/4” and 3.5. To
use the Floppy Disk i.e. to read or write data from to floppy disk, it needs to be inserted into the floppy disk
drive. There are three standard size of disc with three density
Single density, double density , high density.
The density refers to the amount of data that can be store in a given standard area that is Bit per
inch of the track.
The drive has a spindle, which rotates the disk. It also has read/write read which is positioned one
specific location on the disk surface by the drive to perform read/write operation. The central cut
of the disk is means for drive spindle, which will rotate the disk that is 300 to 360 rpm. .
5.25” Disks
Speed in Rpm
Data transfer rate in
Track per surface
Sector per surface
3.5” Disks
Double density
High density
High density
1.2 MB
720 KB
360 KB
1.44 MB
It is collection of disks mounted vertically one over the other. Each disk has both sides recording surfaces.
The disk drive has got a motor to rotate the disk pack about its axis at very high speed i.e 3000 to 3600 rpm
mounted on arms. Presence of multiple heads makes the data access faster. Same tracks of all the disks
mounted vertically constitute the cylinder. The arms move in union. When the read/write head is on
particular sector of a track the read or write operation is performed. Actually to read data record the address
of the data record i.e Cylinder no., Surface no., Sector no is to be determined. Then the read/write head is
positioned on that sector of the surface and performs the read/write operation. If the fixed disk pack is put
under a completely sealed system then it is known as Winchester disk. Hard disk is normally faster device
and has capacity very high also. Present days hard disks are having capcity 20 GB, 40 GB.
The components of hard disk enclosed into a dust proof metal package. Disk is a metal plates which is
coated with magnetic oxide.
cylinder 0
cylinder 399
Hard disks are rigid platters,
composed of a substrate and a
substrate – the platter’s base
material – must be nonmagnetic and capable of being
machined to a smooth finish. It
is made either of aluminum
alloy or a mixture of glass and
ceramic. To allow data storage,
both sides of each platter are
coated with a magnetic
medium – formerly magnetic
oxide, but now, almost
exclusively, a layer of metal
called a thin-film medium.
This stores data in magnetic patterns, with each platter capable of storing a billion or so bits per
square inch (bpsi) of platter surface.
Platters vary in size and hard disk drives come in two form factors, 5.25in or 3.5in. The trend is
towards glass technology since this has the better heat resistance properties and allows platters to be
made thinner than aluminium ones. The inside of a hard disk drive must be kept as dust-free as the
factory where it was built. To eliminate internal contamination, air pressure is equalised via special
filters and the platters are hermetically sealed in a case with the interior kept in a partial vacuum.
This sealed chamber is often referred to as the head disk assembly (HDA).
Typically two, three or more platters are stacked on top of each other with a common spindle that
turns the whole assembly at several thousand revolutions per minute. There’s a gap between the
platters, making room for magnetic read/write head, mounted on the end of an actuator arm. This is
so close to the platters that it’s only the rush of air pulled round by the rotation of the platters that
keeps the head away from the surface of the disk – it flies a fraction of a millimetre above the disk.
On early hard disk drives this distance was around 0.2mm. In modern-day drives this has been
reduced to 0.07mm or less. A small particle of dirt could cause a head to crash, touching the disk
and scraping off the magnetic coating.
On IDE and SCSI drives the disk
controller is part of the drive itself.
There’s a read/write head for each side
of each platter, mounted on arms which
can move them towards the central
spindle or towards the edge. The arms
are moved by the head actuator, which
electromagnetic coil that can move a
magnet very rapidly. Loudspeaker
cones are vibrated using a similar
The heads are designed to touch the platters when the disk stops spinning – that is, when the drive
is powered off. During the spin-down period, the airflow diminishes until it stops completely, when
the head lands gently on the platter surface – to a dedicated spot called the landing zone (LZ). The
LZ is dedicated to providing a parking spot for the read/write heads, and never contains data.
Bit signal
Reflect Beam
Beam Beam
Optical Disk
Optical disk is the latest
developed secondary storage
device. It consists of a disc
coated with reflective material.
Data access is performed by
focussing high power laser
beam on the surface, sensing
pits & lands. Storage capacity is
enormous in comparison to
floppy disk. There are 3 types of
CD_ROM is similar to music
CDs available in the market. It
has Read only facility and write
is not be erased. To read the
contents a low power laser
beam is focused on the disk
Smooth surface reflects more light and
pitted portion reflects less light. The
reflected light is sensed by a detector and
converted into electrical signals. Unlike
magnetic disk, which has one long track,
which starts at the outer edge and
continues in a spiral manner towards the
center. This spiral track helps in reading
large blocks of sequential data like music. It
has very slow access time. Cost per bit is
very low in comparison to magnetic
materials. Optical disk drives do not have
any mechanical read/write heads as it
involves laser technology. This causes the
disk less damage sues to wear and tear and
hence has a long life. In WORM, write once
Read many disk, data can be written by the
user but only once. It can not be erased subsequently. In Erasable disk, contents can be erased and written
again into the optical disk. Typical capacity of optical disk is 650 MB.
A recordable DVD stores up to 2 hours of very good quality DVD-Video, including several audio tracks in
formats like stereo, Dolby Digital or DTS and also advanced menu systems, subtitles and still pictures that
can be played by many standalone DVD Players and most computer DVD-ROMs.
DVD stands for Digital Versatile/Video Disc, DVDR stands for DVD Recordable and DVDRW for DVD
Rewriteable. If you're familiar with regular audio/music CDs or regular DVD-Video discs, then you will know
what a recordable DVD looks like.
Classification of Computers
Although a clear cut classification of computers is difficult, computers can be broadly classified on the basis
of purpose. Components and size.
Analog Computers
 Analog Computers
Analog computers are computers that measured physical quantities (e.g.
 Digital Computers
pressure, temperature, length etc.) and convert them to numeric values.
 Hybrid Computers
For example a thermometer does not perform any calculations but
measures the temperature of the body by comparing the relative
expansion of mercury.
Analogs Computer are used mainly for scientific and engineering purpose because they deal with quantities
that vary constantly. They give only approximate results.
Digital Computers
Most computers are digital devices i.e., they count the numbers for digits) that represent numerals, letters, or
other special symbols.
Special purpose digital computers can be fixed permanently in the machine e.g. processors that are installed
in automobiles to control fuel, braking systems etc.
General-purpose digital computers can be used in different applications since they can store different sets of
instructions and programs.
Hybrid Computers
The features of analog and digital machines are combined to create a hybrid computing system. For e.g.
analog devices measure a patient‟s vital signs like temperature, heart functions. These are then converted to
numbers and supplied to the digital components that monitor the patient‟s vital signs. Any fluctuations can
thus be noticed immediately.
Modern computers vary in size from large computers that fill entire rooms to the CPU that is smaller in size
than the nail of the little finger.
Computers can thus be classified as Supercomputers, Minicomputer and Microcomputers, according to their
While large systems have greater processing speed, greater storage capacity are able to handle large
number of powerful input and output devices, the smaller processors generally cater to single users. They
may be
Special purpose devices performing a single task e.g. controlling the ignition system in an
automobile or
Personal computers ranging from the desktop model to the lap top to the notebook.
The microcomputer is the smallest type of computer available. Inside a microcomputer. The arithmetic and
control units are combined on a single chip called a microprocessor. Microcomputer contains two types of
store or memory..
Microcomputers are used as home computers for the family or as personal computer by business executives
or by small business where volumes of data processing and speed requirements are small.
These computers are popular as home computers, having a small memory, which uses the household TV as
the display device and a cassette player or a small capacity floppy for backing storage.
Minicomputers are more powerful than the microcomputers and can support several users. They have larger
RAM and backing storage capacity and can process data more quickly.
The first popular minicomputer was the PDP-8 launched in 1965. Minicomputers were basically developed
for use in process control systems. The minicomputer has been diversified to handle common applications
also. A medium sized organisation may use it for applications like processing of payrolls and financial
accounts, handling costing. Sales analysis, production planning and a host of other similar activities.
Minicomputer may also be used for systems like reservation or banking.
Examples of popular minis are the PDP-11 and the VAX 7500.
The earliest computers were called mainframes due to their large size. The term is still used for the large
computers to today. The capacities of the earlier mainframes and the mainframes of today are enormously
different. Today‟s mainframes are far more powerful, so much so that a microcomputer today comes close to
the power of an earlier mainframe.
Mainframes are very large computers with a very high capacity of main store. Because they can process
large amounts of data very quickly, big companies, banks government departments as their main computer,
use them. They can be linked into a network with smaller departments computers, microcomputer or with
each other. They act as hosts of large national and international communication networks, handling
hundreds of users.
Further development in mainframe computing has been that of distributed systems. In a distributed system,
some processing power is provided at the local end of a company‟s communication network, and the other
end is linked to a central computing facility.
Examples: IBM 4381
Super Computer
These are the fastest computers. These machines are specially designed to maximize the number of FLOPS
(Floating-Point Operations per Second). Anything below 1 Giga flops/ Sec. is not considered to be a super
computer. Super Computer has unique highly parallel architecture in order to achieve this high speed. These
are effective only on a mall range of problems. Super computer are used for large-scale numerical
calculations such s weather forecasting, Aircraft design and simulations.
Examples: Parma, Cray, NEC-500 etc.
Capabilities and Limitations of a Computer
The computer is the most powerful tool developed by man, till date it is completely dependent on the human
being. No matter how good a computer is, it has to be „told‟ explicitly what to do. Some o its capabilities and
limitation are as follows.
1. Computers are very fast. They can process millions of instructions per seconds (MIPS is the unit for
measuring the processing speeds).
2. Computers are accurate. They do not make mistakes in calculations.
3. Computers perform complicated and repetitive tasks very well, without error, for long periods of time, as
they do not suffer from carelessness, boredom or tiredness.
4. The efficiency of a computer does not decrease with age. Unlike mechanical or electrical devices, the
speed of a computer remains the same over a number of years.
5. Computers are very versatile. They can do a variety of jobs depending on the instruction fed to them and
their hardware characteristics. Modern computers are capable of handling not only complex arithmetical
problems, but also host to jobs unrelated to numbers, like railway and ir line reservations etc.
1. Unlike the human brain, a computer cannot think on its own. It has to be given every detailed instruction
and every step of its operations has to be described. It cannot detect laws in logic input to it.
2. The computer will either produce erroneous results or simply give up the task if a situation occurs that is
outside the scope of the instruction specified to it.
3. Humans have the potential to try out various alternatives to solve the unexpected which computers do
not have.
4. Computers have no intuition. Computers cannot draw a conclusion without going through all
intermediate steps.
5. Computers can only process jobs, which can be expressed in a finite number of steps leading to a
specific goal. Each step must be clearly defined. Also, the next step to process as well as where to find
the next step must be stated clearly.
6. Computers cannot handle Combinatorial Explosion. Computers cannot handle situations where a finite
number of steps generate an impossibly large number of computer operation.
Pentium Series Computers
Intel Processor Generations Summary
8086 (1)
80286 (2)
80386 (3)
80486 (4)
Pentium (5)
Pentium Pro (6)
Pentium II
Pent. MMX
Pentium 3
Pentium 4 (7)
Celeron II
Intel Core (8)
Intel Core 2 Duo processors are next gen processors , whole new Processors
Intel Dual Core Processors are just launched striped down version of Core 2 Duos there are 2 in Market
for Desktop range, E2140 runs at 1.6 GHz with 1 MB L2 and 800 MHz FSB and E2160 with 1.8 GHz
with same specs of E2140........they were launched with a very low price to counter the market of super
The Core 2 Duo has two cores inside a single physical package. The Core 2 Quad has four cores in its
package. In applications that utilize multithreading, such as Photoshop or video editing, you will see a
tremendous improvement over a Core 2 Duo at the same clock speed. In single-threaded applications,
Actual Difference between both Process is about Load Balancing. DUAL CORE have two
Processors in Series both working at same time. while CORE 2 DUO have two Parraral
Processors which sharing their load. if one processor heatup then it transfer load to next
processor. means parraral processing.
I/O devices
It is the input and output devices that form the essential link between the user of the computer system and
the computer system itself. These devices form the “Interface” between the user and the system.
Input devices are required to get raw data into the computer. Output devices are those which output the
processed information.
In the early years of computing punched cards and punched paper tape were used to input data into the
computer. The output was generated on punch cards or paper tape which was then fed into machines like
telex printers, or into tabulator printers.
Over the years, the technology advance his given much scope in the design of input and out put devices.
Input Devices
Keyboard is the most commonly used input device. In the Key Board the keys are arranged in matrix form
having rows and columns. As soon as a key is pressed, the microprocessor scans all the keys for the key
press and detects which key is pressed. Then corresponding code to the key is sent. When a key is pressed
the metal moves and contacts the metal plate below it, which closed the circuit. From this it is sensed as to
which key is pressed. When the key is released the circuit is open. With new features of operating system
number of keys in the computer keyboard is increasing. The keys in the keyboard are grouped into these
Alphanumeric Keys
Numeric Keys Pad
Special Keys
Function Keys
Alphanumeric keys and numeric keys cause the corresponding characters
appear on the monitor screen. But special keys and function keys do not have
specific alphabet and numeral associated with them. Special keys are used to
perform some action and function keys are used to perform some function as
defined by the software or user.
Mouse is another input device. It is called pointing input device. It is uses in association with visual display
unit. It is a small box with, about the size of a tape cassette with a round ball on the bottom and one or more
buttons on the top. The mouse is attached to a terminal or microcomputer by a cable.
A mouse enables the user to manipulate a pointer or on arrow on a terminal or microcomputer screen. When
the user rolls the mouse across a flat surface, the screen cursor moves in the direction of the mouse‟s
movements – (this movements is measured in hundredths of an inch).If the user rolls the muse forward and
to the right the cursor moves up and to the right on the. Such movements enable the user to:
Point to icons or tiny pictures that identify processing choices
Point to line items in lists
Draw lines and pictures on a screen
With the click of a button the system can be notified of this choice.
Since the cursor follows the way the users hand moves the muse, the user has a sense of pointing
something on the screen. With proper software mouse can be used to draw pictures and edit text.
Other input devices
There are other input devices that are often used with PC‟s.
Scanner All scanners are essentially “optoelectronic” devices, which convert any type of printed or written
information including photograph into digital pulses, which can be manipulated by computer into any mode.
Scanners and digitizers have been developed to electronically store printed data. Some system can identify
printed characters. Others break down printed images into bits of data, store them and then and then
translate the bits into an image on a monitor or printer. The simplest scanner can only read specially shaped
characters, such as those on checks or grocery products. More powerful scanner identifies a variety of
type‟s faces, hand lettering, and complex graphic designs. Top –of – the – line system use lasers to create
high-resolution color and black and white photographs.
Scanner consists of two components.
First is data- capturing subsystem illuminates the document so that the image can be recorded.
Second is image -processing subsystem uses sophisticated software to convert the optical images into
digital form and store the data in a file.
Engineering Scanner are quite expensive, usually several hundred thousand dollars, still their ability to
simplify the creation and revision of graphic designs result in an increased productively gain over older
Touch Screen
It is a computer screen designed or modified to recognize the location of touch on its surface. By touching
the screen, the user can make a selection or move a cursor. The simplest type of touch screen is made up
of a grid of sensing lines, which determine the location of a touch by matching vertical and horizontal
contacts. Another more accurate type uses an electrically charged surface and sensors around the outer
edges of the screen to detect the amount of electrically disruption and pinpoint exactly where a contact has
been made. The third type embeds light emitting diodes (LED‟s) and sensor around the outer edges of the
screen. This creates an invisible infrared grid, which the user finger interrupts, in front of screen. Touch
screens are very popular in applications such as information kiosks and automatic teller machines (ATM).
Optical Mark recognition (OMR)
The OMR devices can scan marks from a computer-readable paper. Such device are used by universities
and institutes to mark test sheet where the candidate select and marks the correct answers from multiple
choices given on a special sheet of paper these mark sheets are not required to be evaluated manually as
they are fed in the OMR and the data is then transferred to the computer system for further evolution
The actual technique used by an OMR device once again involves focusing a light on the page being
scanned. Thereby detecting the reflected. Light patterns for the marks .pencil marks made by the user
reflected the light determining which responses are marked.
Answer sheet 1.a b c d 2.a b c d 3.a b c d 4.a b c d.
Magnetic ink character Recognition (MICR)
Magnetic ink character recognition is like an optical mark recognition device and is used only in the banking
industry. MICR device scan cheque number directly from the cheque leaflets and then automatically feed
them in the computer system for further use, doing the job quickly, accurately and efficiently.
Bank using MICR technology print cheque books on special type of paper .the necessary details of
the bank( like the bank‟s identification code ,relevant account number and cheque number)are pre-printed
on the cheques using an ink that contains iron oxide particles that can be magnetized.
Barcode reader
Data can be coded in the form of light and dark bars with coded spacing and thickness. These are called
barcodes, which are commonly used to identify items. Each item is labeled with a Universal Product Code
(UPC). The code is read by a wand or pen, which transmits a laser beam and receives the reflection from
the label. These pulses are compared with standard codes st1ored in the computer. A barcode is commonly
seen on the back of any book published in recent times.
The optical mark reader (OMR) is a device, which can detect the presence or absence of a mark on a paper.
Light is incident onto the paper and the reflected light is detected. The presence of a mark is detected due to
intensity of light being reflected from the mark. OMR is used in reading answer sheets, questionnaires.
Optical Character Reader (OCR) is an improvement over OMR. This can not only detect a mark but can
also recognize its shape and identify characters directly from source of the character and the OCR can
detect and interpret these minor differences. However, documents have to be filled very carefully and
character shapes have to be fairly precise. Using machines to print the characters often does this. The
presence of any other marks can confuse the device.
Direct reading of documents can be done at about 1500 characters per second No data conversion is
required. These readers are popularly used to process turnaround documents produced as output and
reused as input by the computer e.g. an electricity bill is printed with all the information required for re-input
on a tear- off section, If the precise amount stated is paid by the customer, the returned portion is used for
direct input to the computer.
Advantages of OCR
The primary advantage of OCR is that it eliminates some of the duplication of huma
N effort required to get data into the computer. Thus improves data accuracy.
It increases the timeliness of the information processed.
The chief advantage of OCR is the ability to use source documents as direct inputs to a computer,
thereby avoiding data transcription.
Disadvantage of OCR
However, difficulties in using OCR equipment may be encountered when document
To be read are poorly typed or have strike over or erasures.
The OCR can be expensive in comparison with other input devices.
Video Display unit is the most commonly used output device on most personal computers. Visual display
unit is another name for monitor of a computer .There are two basic types of VDUs. First is the typical
monitor that you see on a desktop computer which looks like a television screen. This type of monitor uses a
large vacuum tube called cathode ray tube. The second type, known as the flat panel display is used
primarily with portable computers .There are several types of flat panel monitors but the most common is
Liquid crystal display monitor .LCD monitors creates images with a special kind of liquid crystal that is
normally transparent but becomes opaque when charged with electricity.
The physical size of a monitor's display area has an obvious bearing on how well you can see images. The
resolution of a visual display unit can be classified by the number of pixels on the screen, expressed as a
matrix e.g 640 x 480.The refresh rate is the number of times per second that the electron gun scan every
pixel on the screen and is measured in Hertz. Dot Pitch is the distance between the phosphor dots that
make up a single pixel
Normally a VDU will have 24 lines of 80 characters each.
MGA (monochrome graphics adapter)-: The MGA supports only one color the brightness intensity of the
system can be changed. It has very low resolution power.
CGA (color graphics adapter)-: The CGA supports both text and graphics mode. It functions in color and
monochrome modes in various resolutions. The CGA works with different types of monitors. However, it
gives poor display quality in the text mode. The typical resolution is 640 X 200 (i.e. 640 row X 200
columns)in the graphics mode.
HGA (Hercules Graphics Adapter)-: It is a monochrome adapter with an additional graphics display mode,
which provides high resolution monochrome graphics. In text mode it offers a resolution of 750 X 350 dots
better then the CGA. HGA having no color although it offers brightness and intensity offers.
EGA (Enhanced Graphics Adapter)-: It was develop in an effort to unify the Varity of adapters. EGA
combines all the features of above adapters and provide high resolution with 16 colors at a time.
VGA (Video Graphics Array Adapter)-: It supports 256 colors at a time with high resolution.
SVGA (Super Video Graphics Adapter)-: The SVGA is the advanced system of VGA. It works in two
combinations of resolution and colors then SVGA provides
640 X 480 pixels with 256 colors
1024 X 480 pixel with 16 colors
Visual Display Unit are capable of showing millions of colors. In a Visual Display Unit the screen is
refreshed after a specific time. The refresh rate is used to measure the number of time a screen is
refreshed in a second. The high refresh rate provide better picture quality.
Resolution is the unit to measure the sharpness of the images. More pixels provides better
CRT (Cathode Ray Tube)
 High dynamic range (up to around 15,000:1), excellent color, wide gamut and low black level. The
color range of CRTs is unmatched by any display type except OLED.
 Can display natively in almost any resolution and refresh rate
 No input lag
 Sub-millisecond response times
Large size and weight, especially for bigger screens (a 20-inch unit weighs about 50 lb (23 kg))
High power consumption
Generates a considerable amount of heat when running
Geometric distortion caused by variable beam travel distances
Can suffer screen burn-in
Color displays cannot be made in sizes smaller than 7 inches (5 inches for monochrome). Maximum
size is around 24 inches (for computer monitors; televisions run up to 60 inches).
LCD (Liquid liquid crystal display (LCD) )
TFT -Short for thin film transistor, a type of LCD flat Very compact and light
panel display screen, in which each pixel is controlled by
 Low power consumption
from one to four transistors. The TFT technology provides
 No geometric distortion
the best resolution of all the flat-panel techniques, but it is
 More reliable than CRTs
also the most expensive. TFT screens are sometimes
 Can be made in almost any size or shape
called active-matrix LCDs.
 No theoretical resolution limit
 Limited viewing angle, causing color, saturation, contrast and brightness to vary, even within the
intended viewing angle, by variations in posture.
 Bleeding and uneven backlighting in some monitors, causing brightness distortion, especially toward
the edges.
 Slow response times, which cause smearing and ghosting artifacts. However, this is mainly a
problem with passive-matrix displays. Current generation active-matrix LCDs have response times
of 6 ms for TFT panels and 8 ms for S-IPS.
Main article: Plasma display
 High contrast ratios (10,000:1 or greater,) excellent color, and low black level.
 Virtually no response time
 Near zero color, saturation, contrast or brightness distortion. Excellent viewing angle.
 No geometric distortion.
 Softer and less blocky-looking picture than LCDs
 Highly scalable, with less weight gain per increase in size (from less than 30 in (760 mm) wide to the
world's largest at 150 in (3,800 mm)).
 Large pixel pitch, meaning either low resolution or a large screen. As such, color plasma displays
are only produced in sizes over 32 inches.
 Image flicker due to being phosphor-based
 Heavy weight
 Glass screen can induce glare and reflections
 High operating temperature and power consumption
 Only has one native resolution. Displaying other resolutions requires a video scaler, which degrades
image quality at lower resolutions.
 Fixed bit depth. Plasma cells can only be on or off, resulting in a more limited color range than LCDs
or CRTs.
 Can suffer image burn-in. This was a severe problem on early plasma displays, but much less on
newer ones
Printer is an output device, which is primarily used for producing output in the paper in user readable form.
The printed output is called hard copy . The printers are classified into two categories based on the
technology used for printing.
Impact Printer
Non-impact Printer.
Impact printers make provision for hitting the paper while printing, where as non-impact printers print
without hitting the paper or giving any impact to the paper. Line printer, Dot matrix Printers, Daisy
wheel printer comes under impact printers. Laser printer, Inkjet printer comes under non-impact
printers. Speed of non-impact printers is usually measured in pages per minute. Quality of printing is
better in non-impact printer than impact printers varieties of fonts, layouts, drawing can be better
printed in non-impact printer that impact printer. Cost of non-impact printer is high. These are mostly
used with personal computers.
A line printer prints a whole line at a time. There are normally 132 or 136 column per line. The line printer
consists of a drum which rotates at a speed of 600 to 2000 RPM (Revolution per minute). The drum has all
the characters formed on the surface of it. Each row on a drum has a single character repeated on it. For
example in a 132 column printer. 132 times each character repeatedly occur in a row. First row has a 132
character A the next row 132 B‟s the third row has 132 C etc. If a printer is capable of printing 100 different
characters then it will have 100 rows.
A 9-pin dot matrix printer has a printing head with 9 needles on it. The needles are arranged one
below the other in a single column. Each pin can be independently activated electronically. The needles are
spring loaded. So when the pin is not activated, the needle tip stays within the print head. When the pin is
activated, it is projected slightly outside from the print head. In dot matrix printer with 9 pins character is
defined as matrix of 5x7 dots. That is 5 columns by 7 rows. As the printer head moves from left to right each
columns is printed by the print head. Normally the top most and the bottom most needle are not used much.
The top –most needles is activated for character like „t‟ and the bottom most needle is activated only for
characters per second. The output quality of the 9 pin dot matrix printer is poor because of the gap between
the 9 pins. To overcome this disadvantage printers are available with 24 pins, which gives good quality
output, since the inter-pin spacing is less in these 24 pin dot matrix printers. Speed is measured in character
per second.
In daisy wheel printer, the characters are embossed in the arms of a wheel called daisy wheel. In this printer
there is only one strike hammer. Like typewriter, an inked ribbon will be kept between the paper and
hammer. To print a character the arm will be rotated to bring the character between the ribbon and the
hammer. The hammer strikes the arm making an impression of the character on the paper. Print quality is
good. Printing speed of daisy wheel printer is very slow. The printing speed will be between 25 to 60
character per second. Speed is measured in characters per second.
Ink-jet printer use electrostatic ink in it. The printer head has a specially designed nozzle. It sends small
droplets of ink at high speed. An electrostatic plate placed just outside the nozzle deflects each ink droplet.
The deflected ink settles on the paper. Like this many droplets are sent to form a character.
In a color ink-jet printer, three nozzles are present, to inject three different colored ink. Red, Blue
and green colored inks are used in these nozzles. These colors mix together to produce various colors.
Speed is measured in pages per minute.
As inkjet prints through a pattern of tiny dots, it can print any shape of characters, any size of
characters and also print graphics, charts, graphs, pictures etc. Inkjet printer produces higher quality output
than the dot-matrix printers.
Laser printer prints one page at a time. The laser printer uses laser technology to print the first copy and
copier technology to print the first copy and copier technology to output additional copies. It is capable of
producing very high quality print out very quickly. It also offers wide selection of fonts. Laser printer operates
at a speed of 4 to 20 pages per minute. In a laser printer, the signal coming from the computer is sent to a
laser beam in the laser printer. The laser printer. The laser beam will be deflected by the laser printer. A
revolving mirror will deflect the laser beam, so that the laser beam can scan the revolving from. Wherever
the output is supposed to be white, the laser beam will discharge the charge from that part of the drum. The
laser printer has high print density. It can print normally at densities of the order of 300 dots per inch. High
quality printers can print upto 1200 dots per inch. Speed is measured in pages per minute.
This is one output Device which produces output in the form of a graphical picture. This is used for printing
larger size graphs and drawings and designs. Even though the printers discussed above are capable of
producing graphical output, these are not suitable for printing engineering design application or mechanical
component design which requires high precision, perfectly proportioned graphic output on large sheets
plotters are best suitable for such applications. The pen moves on the paper and plots the graph. Color
plotters use multiple color pens. There are two types of plotters available.
Flat Bed Plotter
Drum Plotter
Software may be defined as set of instructions stored as programs that govern the operation of a computer
system and make the hardware to run. Software is Intangible. It is the logical part of the computer system.
Software is nothing but the collection programs to achieve a task or for a particular application. It is
responsible to operate different hardware component.
Role of Software in Computer:
A set of instructions that perform a particular task is called as software/ program. The instructions in the
program direct the computer to perform input operations, process the data and output the results. Collection
of programs to automate a task is known as software. Both hardware and software are made for each other.
Software requires a base of hardware for their execution, same hardware requires software to operate.
Software is collection of program files so the resident of software is Disk.
Instructions ( which tells to computer to perform a particular operation)
Programs (Set of instructions)
Software (Set of programs)
Categories of Software:
Software has many function in a computer system. Depending upon he various use of software, It is mainly
classified into the following types:
System Software:
System software is a collection of master programs designed to operate
System Software
the computer and control its activities. The computer manufacture or
Service Software
independent software developers either provide system software. They
are general programs written to assist users in the use of the
Applications Software
computer systems by performing tasks such as controlling all of the
operations, moving data into and out of a computer and all the other
steps in executing the application programs.
In general system package supports the following:
Running other software.
Communicating with peripheral devices such as printers, disk and tape drivers etc/
Developing of other type of software.
Monitoring the use of various hardware resources such as memory, peripherals, CPU etc.
An operating system is a set of programs which manages the overall functions of the computer..
Following are the role of an Operating Systems:
Resource Management
Process Management.
Priorities, Protection and parallelism
Memory Management
Information Management
The utility of systems programming is to increase the productivity of various
applications for operation on a computer. System programming is mainly achieved
using machine language or assembly languages. This involves a great deal of
technical knowledge as the programmer has to directly interact with the hardware of
the computer.
Developing of system software is called system‟s programming. The most important
system software is the operating system, which governs all the activities of the
computer. Example of operating system is MS-DOS, OS/2 Wrap, VMS MultiFinder,
MVS, DOS/VSE, UNIX, XENIX, Linux Windows‟s 95/98/2000, Windows NT etc.
An operating system is a set of programs which manages the overall functions of the computer..
Following are the role of an Operating Systems:
The utility of systems programming is to increase the productivity of various applications for operation on a
computer. System programming is mainly achieved using machine language or assembly languages. This
involves a great deal of technical knowledge as the programmer has to directly interact with the hardware of
the computer.
The purpose of all operating systems is much the same; to control the computer activities. Operating
systems differ in how they do their job and in what additional features they offer, like; Multiprocessing,
Multiprogramming, Multitasking, Time Sharing etc.
Service Software:
Service software are those software which provides various services to computer users in order to
programs the computer. It ranges from Compilers, Assemblers to Debugger, loader and other utility service
programs. They are used to convert the program instructions of High level languages to their equivalent
machine languages form.
We have different types of service software.
An interpreter is a program which translates one statement of a High –level languages programs into
machine codes and executes it. In this way it proceeds further till all the statement of the program are
translated and executed. The execution time of the programs increases considerably. It displays errors
Compilers are a collection of large programs stored normally on a secondary storage medium. They are also
used to convert HLL instruction into machine language and an object program is generated. Each HLL have
their own compiler. Like (COBOL complier, FORTRAN compilers etc…). A complier is more intelligent than
an assembler but its programs execution time is more, and occupies a larger part of the memory. But the
execution speed of the programs increases tremendously. It has low speed and low efficiency of memory
utilization. If a complier runs on a computer other than that for which it produces object code, then it is called
a cross- complier. It displays all errors at a time.
HLL program ------------------Languages -------------------------Machine code
(Source code)
(Object program)
In order to execute an assembly language program on a computer, it should be first translated into its
equivalent machine language programs. The translator which does this known as Assembler.
Assembly language ----------------------- Assembler ----------------Machine language
1. Compiler complied program’s
1. Execution Speed is slower. Because every time
Execution speed is faster.
you run the program the lines will have to be reinterpreted.
2. Program execution time is more.
2. Execution time is slower.
3. Always the source code is not
3. The source code is always necessary.
4. Debugging is more difficult.
4. Debugging is easier since one can write one
or two lines of the source code & run it in
case of any mistakes. The exact line where
the mistakes has been made is printed out.
5. Object code does not require
the compiler to run.
6. It occupies more memory space.
7. It cannot be used in smaller systems
where less Memory is available.
5. The source code always requires the interpreter to
6. It occupies less memory space.
7. It can be run in smaller systems where limited memory is available.
Editor is a program, which makes it possible to store the source program in RAM, and provides access
to it directly for error correction, organization or restructuring etc.
Loader is a program the machine code of a program into the system memory. It accepts the program either
in absolute or re locatable format. If a program is in absolute format (i.e. the actual address of the instruction
and the data are supplied by the programmer). The loader simply loads the program into the system
memory. But if it is re-locatable format, the locaer assigns a specific addresses to each instruction and data
before the loader loads the program into memory.
It is program that helps the user to locate and correct logical mistakes in his program. This process is called
A simulator is a device, data processing system, or a computer program that represents certain features of
the behavior of a physical or abstract system.
These are hardware or software designed to cause on device, such as a computer, to behave as if it were
another. A terminal emulator is a program that enables a microcomputer to pretend to be a mainframe
terminal by using the procedures and codes expected of the mainframe.
Application Software:
Application software is a computer designed to help people to perform certain type of work. It is a set of
programs, which are written by computer users or programmers to meet their information processing
requirements. These programs do specific jobs for the user. Such as financial accounting, pay roll, inventory,
etc. Application Software usually comes in the form of package programs, which deal with all activities of a
specific application of the industry in any field. Also supplied, as part of the application packages is a
detailed documentation with instructions on how to use and maintain the package. Regularly they are
revised and update with the increase in business needs and automation trends.
Application software are general software, but a package is a special purpose computer application
consisting of one or more programs created to perform a particular type of task.
Some of the common Package are as follows:
(A) Graphics:
These packages allow the user to do various kinds of Computer Graphics,
Designing and drafting
of various documents etc. can be easily achieved using these packages. E.g..
AutoCAD, etc.
(B) Word Processing: These are designed for the creation and manipulation of textual matter. Thesehave
features for
editing & modifying documents. (e.g. MS-WORD, WORDSTAR)
(C) Spreadsheet:
:These are Numerical data analysis package generally used for generating financial
reports, projections and various other number crunching operations. ( e.g. Lotus 12-3, Ms-Excel).
Licensed Software and Software Update:
Software is the proprietary item of the software developers. When ever, the developer makes major
changes, it publishes the newer versions in magazines and newspapers. If you are a licensed user you can
be benefited when you get the update version of the software.
A language is a means of communication. The programmer makes use of a computer language to
communicate with the computer. A machine is receptive only to simple, unambiguous facts. A programming
language therefore uses a limited or restricted vocabulary.
Versatility of the computer is based on he fact that all of the many different problems that can be solved by a
computer can be broken down to four fundamental operations:
(1) Input & Output operations.
(2) Arithmetic operations
(3) Movement of Information inside the CPU.
(4) Logical or comparison operations.
A programming language consists of all symbols, character and usage rules that permits people to
communication with computer.
Computer language can broadly be classified into two types of language.
Machine Level Language:
This language is the only language that a computer can understand. In this language all the instructions are
coded in terms of 0 and 1. Since the language involves only two digits, normally 0 and 1, it is also known as
binary language.
The machine language used initially to write programs was cumbersome inconvenient and probability of
committing mistakes was very high. Only expert programmers could use this language. Moreover different
machine uses different codes. The binary code for certain operation differs from computer to computer. Each
microprocessor has its own instruction set and corresponding machine codes. Programmers have to write
their programs according to the machine used by them.
Advantages and limitations of Machine Language:
The computer can execute program written in machine language very fast. This is mainly because CPU
mainly understands machine instruction.
This limitations are, machine language is Machine Dependent, Difficult to program, Error Prone, Difficult to
Assembly Level Language (Low Level Language):
To avoid difficulties in using the machine language a new symbolic language, called Assembly language
was developed. All instruction words which direct the computer are stored in machine in numerical form This
language used symbolic codes such as ADD, SUB, MUL, DIV, etc. to denote various operations such as
Addition, Subtraction, Multiplication, Division respectively. These codes are called Mnemonic codes.
Mnemonic means memory aid, is a name or number use for some code or function. All computer language
are made up of mnemonic except the machine language. A typical instruction word of Assembly Language
Translator, which could translate the Machine codes to binary language, is Assembler, which translates
assembly level language to Machine level language.
The problem of an assembly language is that it is more closely related to the structure of a computer than to
performance of the task. So the programmer spend more time in manipulating the registers rather than
solving actual problems.
High Level Languages:
The development of high level language brought revolution in the field of computers. To overcome the
difficulties associated with assembly languages, high level or procedure-oriented languages were
developed. The instructions written in high level languages resemble ordinary statements in English and are
very easy to understand. Further more it is not necessary for a programmer to remember the address of the
memory location where the data is store. Besides, he need not have a precise knowledge of the architecture
of the computer he is using. The high level language are easy to learn and use.
A large number of high level language are being used in these days, the most common are:
High level Language are machine independent. This is very valuable advantage. High level Languages
independent of Computer architecture. A program written in one machine can be run in other machine.
Usually a longer program is divided into a number of smaller sub-programs called modules. It is easier to
develop and debug smaller programs. A Linker is a program that links (combines) smaller programs or
procedure to form a single module. The Linker library files with the main module. Further the linker machine
codes of the program after the compiler compiles the source code.
The term generation of computer languages is used to categorize the generic enhancements in the various
computer languages that have evolved over the last 50 years. Each Generation indicates significant
progress towards making computer to use.
First Generation Languages (Late 1940s) – Machine Languages.
Second Generation Languages (Early 1950s) –Assembly languages.
Third Generation Languages (Third Generation Languages Late 1950s through 1970s) High Level
Fourth Generation Languages (Late 1970s on wards) _Including a whole range of query languages and
other OOP languages. 4GLS:
One definition of fourth generation language is that it is non-procedural. In non-procedural languages the
programmer has to specify what has to be done, but how the task is to be done.
In traditional second and third generation languages all the instructions necessary to bring in each record
test for end of the file, repeating a same operation etc., would have to be coded. Thus the command LIST in
FoxPro or dBase software package does what a long program would do in third generation languages like
BASIC, PASCAL or C etc. Some 4GLS are aimed at the end user, ease of use is then a prime consideration
and to cut down or development and maintenance time. Some, such as ORCALE, Offers a number of tools
i.e. SQL, SQL* PLUS, SQL* REPORT and front end tools like DEVELOPER 2000, VB or POWERBUILDER.
Distinctions between Third Generation Languages and Fourth Generation Languages.
Third Generation Language
1. Meant for use by professional programmers .
2. Requires specification of how to preform a task.
3. All alternatives must be specified.
4. Require large number of procedural
5. Code may be difficult to read, understand
6. Difficult to debug.
Fourth Generation Language
1. May be used by non-programming professional
(i.e. users) as well as professional programmers.
2. Requires specifications of what task to perform
(System determines how to perform the task).
3. Default alternatives are built-in. User need not to
Specify these alternatives.
4. Requires far fewer instructions (less than one tenth in
Most cases.
5. Code is easy to understand.
6. Errors are easier to locate because of shorter programms, more structured code, and use of defaults.
What is VIRUS (Vital Information & Resources Under Sieze)?
A computer virus is basically a program written for destructive purpose. It is written in such a way that it can
enter the Computer without the knowledge of the machine or the user. It enters the machine through an
infected floppy or a program. It has the capacity to make perfect copies of itself and cause abnormal
functioning of the machine.
A computer virus is a program and should not be confused with the biological virus, which is an organism,
however both of them have a number of common features as far as their activities are concerned.
VIRUS Virus is a program designed to change the way your computer operates without your permission or
knowledge. When a virus attaches itself to another file, it infects it. Any time you activate an infected file it
can damage files, cause erratic system behavior, or display messages. Some system viruses are
programmed specifically to corrupt programs, delete files, or erase your disk. Viruses are inactive until you
run an infected program, start your computer from a disk with infected system files, or open an infected file.
Once a virus is active in memory it can infect any other programs, local or network, that you run. Files
infected with a virus can be inoculated (the virus is removed from the program).
What is a Worm?
A computer worm is much like a virus but does not need any help from a person to spread. Computer worms
spread from computer to computer via networks. Worms exploit holes in operating system security so it is
important to download and install all patches.
WORM Worms are a close cousin to viruses and Trojan Horses. Unlike a virus they don't infect other
programs. They do however make many copies of themselves in memory, which effectively consumes all
your memory. This leaves no memory to run you regular programs. Your PC may behave very erratically, or
just grind to a halt! Some worms get into your e-mail list and e-mail themselves to everyone on your e-mail
list without you knowledge. When each unsuspecting recipient opens such an e-mail, it broadcasts itself to
everyone on their e-mail list. This is how worms rapidly travel throughout the Internet! Worms can not be
repaired since they are not viruses. They must be erased from your computer, the sooner the better
1. A computer virus attaches itself to a program or
file enabling it to spread from one computer to
another, leaving infections as its travels.
A worm is similar to virus by design and is
considered to be a sub class of a virus. Worms
spread from computer to computer.
2. A computer virus is a small program written to
alter the way a computer operates, without the
permission of knowledge of the user.
The worm consumes too much system
memory, causing web servers, network servers
and individual computers to stop responding.
3. A virus must meet two criteria:
A worm must meet two criteria:
It must execute itself. It often places its own
code in the path of execution of another
Worms exploit holes in operating system
security so it is important to download and install all
It must replicate itself. For example, it may
replace other executable files with a copy of
the virus infected file.
The weak security and similar network
configuration is required to travel.
4. Viruses, which requires the spreading of an
infected host file.
Worms are programs that replicate
themselves from system to system without the use
of a host file.
5. Spread with uniform speed as programmed.
6. It can be attached .exe, .com etc
6.It can be attached to any attachment of email, any
file on network.
Worms spread more rapidly than virus.
A computer virus and the biological virus are similar in the following respects:
1. Both need a carrier to get into the system. The computer virus uses a program or an infected floppy to
get the into the machine.
2. Both are parasites, the computer virus is a parasite on the computer system, it uses the compute
system, it uses the computer resources like memory (work space in which the computer works) and the
programs to replicate itself. It also spreads to other diskettes used on a infected machine.
3. Both have the capacity to replicate themselves and hence spread.
4. Both replicate to such an extent that they finally destroy the carrier used and the other programs/cells.
The computer virus destroys the programs and data on the system.
The major difference between the two is that a biological virus causes physical harm to the organism
attached, where as the computer virus does not cause any physical damage to the system.(Although some
virus are written to cause damage to particular parts of the system. Some viruses unintentionally cause
damage to the system) . But the harm caused by the computer virus to the data/programs stored in it is even
greater. The computer is mainly used to store and manipulated data or information. Thus the loss of
information gathered over a span of time or programs developed after a considerable research and
development cost can be disastrous.
Origins of VIRUS:
The idea of virus started with the probability of writing self-replecating software. This idea was first put
forward in 1950 by John von Nevnan. At that time, most of the programmers excepts a few at AT & T
rejected it as absurd. These few programmers at AT & T worked on it as a recreational game agter office
hours. Each would write code that would destroy other programmers code (Which was out ot destroy their
code) in the memory. The winner would be the person with the maximum number of live codes.
The game was strictly kept within the AT & T premises and was never divulged outside for its destructive
It was Ken Thompson, Co-author of UNIX who while receiving an award disclosed about the existence of
such an game, he also asked programmers to try and write such programs. This was the beginning and
within a short time viruses emerged that destroyed data.
IIIegal copying of software gave a major boost to the development o viruses Software developers whose
software were widely pirated and who got little returns for their efforts, would circulate infected copies of
software to teach a lesson to the users of pirated software.
Activities of a VIRUS:
The first and the foremost objectives of a typical virus is to replicate itself and hence to spread to as many
programs as possible.
Another important objective of a virus is to destroy data or program by overwriting parts of data or program
or by simply erasing them.
Other objectives of virus are to cause some sort of malfunctioning of the computer system.
The Virus can cause the malfunctioning of the computer in a number of ways and it differs from virus to
virus. The malfunctioning caused could be.
To disorganize the data/program (deletion of File Allocation Table)
To decrease the memory ( Space in which the computer works) and also decrease the storage
space of Computer.
To cause storage movements and pattern of the screen, thereby making it impossible to work on the
To understand how the virus causes malfunctioning of the computer, it is important to understand
the normal functioning of the Computer and the way in which Computer stores information and retrieve it
from the storage devices.
Types of VIRUS
There are basically two types of Virus, FILE Virus and the BOOT SECTOR Virus depending on the disk
areas they infect and the way in which they spread. A file virus infects only executable files those with
spreading infect only the executable files. The Boot Sector Viruses on the other hand reside in the boot
sector of the disk and spread by copying onto the boot sector of all the floppies used on the machine. These
virus infect a system only when the system is booted from a infected floppy or disk.
How does VIRUS spread:
The spread of virus to system is mainly through the use of infected floppies. A system can get infected by
running infected programs, by starting a system (Booting) with a infected floppy or by sharing of infected
programs over computer networks.
A virus upon entering a system first monitors the system and then activates itself at proper time to cause
maximum harm to the information stored in the system or after replicating itself on a maximum number of
floppies or on a particular date.
The virus copies itself on the floppies used on the system. This is done to ensure that the floppy when used
on another machines will infect that machine as well. The virus copies onto the boot record if it is a boot
sector virus or onto the executable files like COM and EXE files.
Symptoms of a VIRUS attack:
Frequent hanging of the system , that is the system stops functioning.
Decrease in the Main Memory (The space in which the Computer works).
Decrease in the free spaces available on the floppy disk this is because of increase in the size of the
infected files.
Loss of parts of files. This may be because of partial destruction of the file Allocation Table.
Deletion of a files or a number of files from the diskette. This may be due to partial destruction of
Root directory.
Dramatic decrease in the speed of the system. This may be either due to increase in the time taken
to access floppy diskette or due to virus executing itself between the program.
Appearance of strange message or strange pattern on the screen. It should however be noted that
this could also happen due to other reason and the virus should be ascertained using some virus
detecting software.
Prevention of VIRUS
The following precaution should be taken to prevent the entry of virus into a machine:
Avoid booting the machine with a floppy i.e. from A drive.
If it is required to boot from a floppy use a known floppy that is virus free and with a write protected.
This avoids accidental infection of the floppy. Never use an unknown Bootable Disk.
Write protected your disk when using in on an unknown machine. No program and hence virus can
infect a floppy that is wirte protected. The floppy disk controller and drive mechanism of a properly
working Disk drive does not allow to write onto a write protected floppy.
Never use software that is not original or does not come from a authorised dealer. The chances that
the pirated software may be infected are high.
If it is necessary to use borrowed software (As long as it is not illegal) scan it for being virus free.
Apart form the above precaution the following added measures can be taken to avoid the entry of virus:
Use watchdog programs which monitor the system activity and prompt the user in case a virus
Tries to enter into the system.
Immunization of Diskette/file can be preventing the virus form from infecting the diskette/File.
Detection of VIRUS:
A number of programs are available which can detect can virus and clean the infected disk or programs.
Such programs are called ANTI VIRUS. One such set of program that is widely used in virus scan. It scans
for virus in the computer‟s memory and on the disk. In the event of detecting a virus it notifies the user about
the presence of the virus and prompting the user to take necessary action to remove the virus.
In case there is virus in the memory, it is necessary to immediately shut down the machine and reboot the
system with a clean floppy and then remove the virus form the disk, this is to avoid the virus in the memory
from acting and infecting all the files scanned by scan. The typical massage are given below:
C:/> SCAN A: Scanning memory for critical viruses. Found the die-hard virus active in memory.
Power down the system immediately reboot from a clean write protected system diskette and then re-run
SCAN to determine extent of hard disk infection.
(The message differs from program to program.)
What is a computer Network?
Networking refers that a good communication system with sharing of data & information.
The term computer communication Network indicates transfer of information between various computers
through some communication links. This is also sometimes referred as computer Network or simply
computer communication.
Networking in the simplest sense means connecting two or more computers together for sharing of data and
information & resources which establish a good communication system.
Thus computer Network can be defined as collection of autonomous computer interconnected through a
communication media.
There are basically three goals for which computer are network together.
Resource sharing
Load sharing
Resource sharing is the major goal of computer Networks. Through computer Networks the
Various resources like data, program and other hardware and software of other nodes or machines can be
utilized at a distance place geographically apart. Thus one may not have all the resources one needs at his
place or machine. He can share the resources of other nodes located at a different place at the time of need.
Load sharing is another advantage of computer networks. When one node is overload and some
times with varieties of jobs the sharing of load by other nodes is possible in computer Networks.
Reliability is the most vital factor for which computer Network has an edge over non-interconnected
machines. In the case of unconnected computers, if a machine becomes down due to some hardware failure
then the work at that machine will suffer but in the case of computer networks the work can be carried out
else where in other nodes until the machine is set right. Thus computer Network provides high degree of
In spite of all these advantage there is a potential problem associated with computer Networks.
Security of data in the network possesses great threat. Although there are many methods & technology
developed to check the security aspect, Yet all are not completely fool proof.
Components of Network
2. Workstation (Node)
3. NIC
4. Cable
Software :
1. NOS
2. Driver (Lan Card)
Server :
It is a important component in the network system. It is computer system having high processing
speed and high storage capacity. It runs the network operating system and provides network service to other
computers. Most common type server is FILE server.
A computer is connected to the network that becomes a node /client. it has its own local operating
system software. Different nodes are used by different users for various applications. All nodes are
connected to the server.
NIC: (Network Interface Card)
It is a electronic circuit which provides the port for the cable. In network all nodes requires the NIC.
Different NIC like Ethernet , Arcnet & Tokenring etc.
Cables or Communication Lines:
Various types of cables are
Co-axial cable : It is used in implementing Local Area Network called Ethernet. For the long distance and
high speed data transfer this cable can not be used. These assure that data arrived that at their destination
quickly without error.
Paired Wired Cable: Computer joined by conventional wires are limited in their data rates and transmission
distance. If there are many nodes on the network this slow speed might not be acceptable.
Fibre Optic Cable: Now days the broad band channels using Fibre Optics for transmission. In this cable
data can be transmitted at a high speed that is 100000 characters per seconds. In Fibre Optics the light is
propagated fully in it.
Communication Channels
There are three types of channels used for communication and transmission
1) Narrow Band : It handles low data volumes. The transmission rates are from 45 to 300 bands. Band is
commonly is identified as the number of bits per second can be transmitted through the communication
2) Voice Band : In this band the transmission rate lies between 300 to 9600 band. It used for operating
CRT and Line printers.
3) Broad Band : It handles very large volume of data. This system provides data transmission rate that is
more than one-millenium band. It is used for broad band communication. Satellite communication is the
example of this band.
Mode of Transmission
1) Simplex : In this method data can be send in only one direction. In this system one end is sender and
other one is the receiver. It is one way communication.
2)Half Duplex : In this method data can be send in both direction but nit at the same time. During
transmission one end the sender and other is the receiver. At the next moment sender can be receiver and
receive can be sender.
2) Full Duplex : In this mode both the end worked as a sender and receiver simultaneously. Full duplex is
a faster than other methods.
A network is any collection of independent computers that communicate with one another over a shared
network medium. A computer network is a collection of two or more connected computers. When these
computers are joined in a network, people can share files and peripherals such as modems, printers, tape
backup drives, or CD-ROM drives. When networks at multiple locations are connected using services
available from phone companies, people can send e-mail, share links to the global Internet, or conduct video
conferences in real time with other remote users. As companies rely on applications like electronic mail and
database management for core business operations, computer networking becomes increasingly more
Every network includes:
 At least two computers Server or Client workstation.
 Networking Interface Card's (NIC)
 A connection medium, usually a wire or cable, although wireless communication between
networked computers and peripherals is also possible.
 Network Operating system software, such as Microsoft Windows NT or 2000, Novell
NetWare, Unix and Linux.
Applications of Computer Networks
Numerous applications of computer networking are possible.
Some of the most popular ones include:
 Electronic Mail
 Web-browsing
Digital Libraries
File Transfer
Video / Audio Conferencing
Types of Networks:
LANs (Local Area Networks)
A network is any collection of independent computers that communicate with one another over a shared
network medium. LANs are networks usually confined to a geographic area, such as a single building or a
college campus. LANs can be small, linking as few as three computers, but often link hundreds of computers
used by thousands of people. The development of standard networking protocols and media has resulted in
worldwide proliferation of LANs throughout business and educational organizations.
Metropolitan Area Network (MAN) - NOT EXAMINABLE
A Metropolitan Area Network is a network that interconnects computers in a geographic area larger than that
covered by even a large LAN but smaller than the area covered by a wide area network (WAN). The term is
applied to the interconnection of networks in a city into a single larger network, and it also is also used to
mean the interconnection of several local area networks by bridging them with backbone lines. Several
branches of a chain store within a city might find a MAN useful. MANs are usually connected with fibre-optic
cable, microwave transceivers or leased data landlines.
WANs (Wide Area Networks)
Wide area networking combines multiple LANs that are geographically separate. This is accomplished by
connecting the different LANs using services such as dedicated leased phone lines, dial-up phone lines
(both synchronous and asynchronous), satellite links, and data packet carrier services. Wide area
networking can be as simple as a modem and remote access server for employees to dial into, or it can be
as complex as hundreds of branch offices globally linked using special routing protocols and filters to
minimize the expense of sending data sent over vast distances.
Network Topologies
A network topology is the basic design of a computer network. It is very much like a map of a road. It details
how key network components such as nodes and links are interconnected. A network's topology is
comparable to the blueprints of a new home in which components such as the electrical system, heating and
air conditioning system, and plumbing are integrated into the overall design. Taken from the Greek work
"Topos" meaning "Place," Topology, in relation to networking, describes the configuration of the network;
including the location of the workstations and wiring connections. Basically it provides a definition of the
components of a Local Area Network (LAN). A topology, which is a pattern of interconnections among
nodes, influences a network's cost and performance. There are three primary types of network topologies
which refer to the physical and logical layout of the Network cabling. They are:
1. Star Topology: All devices connected with a Star setup communicate through a central Hub by
cable segments. Signals are transmitted and received through the Hub. It is the simplest and the
oldest and all the telephone switches are based on this. In a star topology, each network device has
a home run of cabling back to a network hub, giving each device a separate connection to the
network. So, there can be multiple connections in parallel.
o Network administration and error detection is easier
because problem is isolated to central node
o Networks runs even if one host fails
o Expansion becomes easier and scalability of the network
o More suited for larger networks
o Broadcasting and multicasting is not easy because
some extra functionality needs to be provided to the
central hub
If the central node fails, the whole network goes down; thus making the switch some kind of
a bottleneck
o Installation costs are high because each node
needs to be connected to the central switch
2. Bus Topology: The simplest and one of the most
common of all topologies, Bus consists of a single cable,
called a Backbone, that connects all workstations on the
network using a single line. All transmissions must pass
through each of the connected devices to complete the
desired request. Each workstation has its own individual
signal that identifies it and allows for the requested data to
be returned to the correct originator. In the Bus Network,
messages are sent in both directions from a single point
and are read by the node (computer or peripheral on the
network) identified by the code with the message. Most
Local Area Networks (LANs) are Bus Networks because the network will continue to function even if
one computer is down. This topology works equally well for either peer to peer or client server.
The purpose of the terminators at either end of the network is to stop the signal being reflected back.
o Broadcasting and multicasting is much simpler
o Network is redundant in the sense that failure of one node doesn't effect the network. The
other part may still function properly
o Least expensive since less amount of cabling is required and no network switches are
o Good for smaller networks not requiring higher speeds
o Trouble shooting and error detection becomes a problem because, logically, all nodes are
o Less secure because sniffing is easier
o Limited in size and speed
3. Ring Topology: All the nodes in a Ring Network are connected in a closed circle of cable.
Messages that are transmitted travel around the ring until they reach the computer that they are
addressed to, the signal being refreshed by each node. In a ring topology, the network signal is
passed through each network card of each device and passed on to the next device. Each device
processes and retransmits the signal, so it is capable of supporting many devices in a somewhat
slow but very orderly fashion. There is a very nice feature that everybody gets a chance to send a
packet and it is guaranteed that every node gets to send a packet in a finite amount of time.
o Broadcasting and multicasting is simple since you just need to send
out one message
o Less expensive since less cable footage is required
o It is guaranteed that each host will be able to transmit within a
finite time interval
o Very orderly network where every device has access to the
token and the opportunity to transmit
o Performs better than a star network under heavy network load
o Failure of one node brings the whole network down
o Error detection and network administration becomes difficult
o Moves, adds and changes of devices can effect the network
o It is slower than star topology under normal load
Generally, a BUS architecture is preferred over the other topologies - ofcourse, this is a very subjective
opinion and the final design depends on the requirements of the network more than anything else. Lately,
most networks are shifting towards the STAR topology. Ideally we would like to design networks, which
physically resemble the STAR topology, but behave like BUS or RING topology.
The OSI Model:
International standard and serves as a guide
for networking. This model is the best known
and most widely used guide to describe
networking environments. Vendors design
specifications of the OSI model. It provides a
description of how network hardware and
software work together in a layered fashion
to make communications possible. It also
helps with trouble shooting by providing a
frame of reference that describes how
components are supposed to function.
There are seven to get familiar with and
these are the physical layer, data link layer,
network layer, transport layer, session layer,
presentation layer, and the application layer.
Physical Layer, is just that the
physical parts of the network such
as wires, cables, and there media
along with the length. Also this layer
takes note of the electrical signals that transmit data throughout system.
 Data Link Layer, this layer is where we actually assign meaning to the electrical signals in the
network. The layer also determines the size and format of data sent to printers, and other devices.
Also I don't want to forget that these are also called nodes in the network. Another thing to consider
in this layer is will also allow and define the error detection and correction schemes that insure data
was sent and received.
 Network Layer, this layer provides the definition for the connection of two dissimilar networks.
 Transport Layer, this layer allows data to be broken into smaller packages for data to be distributed
and addressed to other nodes (workstations).
 Session Layer, this layer helps out with the task to carry information from one node (workstation) to
another node (workstation). A session has to be made before we can transport information to
another computer.
 Presentation Layer, this layer is responsible to code and decode data sent to the node.
 Application Layer, this layer allows you to use an application that will communicate with say the
operation system of a server. A good example would be using your web browser to interact with the
operating system on a server such as Windows NT, which in turn gets the data you requested.
TCP/IP architecture does not exactly follow the OSI model. Unfortunately, there is no universal agreement
regarding how to describe TCP/IP with a layered model. It is generally agreed that TCP/IP has fewer levels
(from three to five layers) than the seven layers of the OSI model. We adopt a four layers model for the
TCP/IP architecture.
TCP/IP architecture omits some features found under the OSI model, combines the features of some
adjacent OSI layers and splits other layers apart. The 4-layer structure of TCP/IP is built as information is
passed down from applications to the physical network layer. When data is sent, each layer treats all of the
information it receives from the upper layer as data, adds control information (header) to the front of that
data and then pass it to the lower layer. When data is received, the opposite procedure takes place as each
layer processes and removes its header before passing the data to the upper layer.
The TCP/IP 4-layer model and the key functions of each layer is described below:
Application Layer
The Application Layer in TCP/IP groups the functions of OSI Application, Presentation Layer and Session
Layer. Therefore any process above the transport layer is called an Application in the TCP/IP architecture. In
TCP/IP socket and port are used to describe the path over which applications communicate. Most
application level protocols are associated with one or more port number.
Transport Layer
In TCP/IP architecture, there are two Transport Layer protocols. The Transmission Control Protocol (TCP)
guarantees information transmission. The User Datagram Protocol (UDP) transports datagram switch out
end-to-end reliability checking. Both protocols are useful for different applications.
Network Layer
The Internet Protocol (IP) is the primary protocol in the TCP/IP Network Layer. All upper and lower layer
communications must travel through IP as they are passed through the TCP/IP protocol stack. In addition,
there are many supporting protocols in the Network Layer, such as ICMP, to facilitate and manage the
routing process.
Network Access Layer
In the TCP/IP architecture, the Data Link Layer and Physical Layer are normally grouped together to
become the Network Access layer. TCP/IP makes use of existing Data Link and Physical Layer standards
rather than defining its own. Many RFCs describe how IP utilizes and interfaces with the existing data link
protocols such as Ethernet, Token Ring, FDDI, HSSI, and ATM. The physical layer, which defines the
hardware communication properties, is not often directly interfaced with the TCP/IP protocols in the network
layer and above.
Transmission Media
Guided Transmission Media
In Guided transmission media generally two kind of materials are used.
1. Copper
o Coaxial Cable
o Twisted Pair
2. Optical Fiber
1. Coaxial Cable: Coaxial cable consists of an inner conductor and
an outer conductor which are separated by an insulator. The inner
conductor is usually copper. The outer conductor is covered by a
plastic jacket. It is named coaxial because the two conductors are coaxial. Typical diameter of
coaxial cable lies between 0.4 inch to 1 inch. The most application of coaxial cable is cable T.V. The
coaxial cable has high bandwidth, attenuation is less.
2. Twisted Pair: A Twisted pair consists of two insulated copper wires,
typically 1mm thick. The wires are twisted togather in a helical form
the purpose of twisting is to reduce cross talk interference between
several pairs. Twisted Pair is much cheaper then coaxial cable but it is
susceptible to noise and electromagnetic interference and attenuation
is large.
Twisted Pair can be further classified in two categories:
Unshielded twisted pair: In this no insulation is provided, hence they are susceptible to
Shielded twisted pair: In this a protective thick insulation is provided but shielded twisted pair is
expensive and not commonly used.
The most common application of twisted pair is the telephone system. Nearly all telephones are
connected to the telephone company office by a twisted pair. Twisted pair can run several
kilometers without amplification, but for longer distances repeaters are needed. Twisted pairs can be
used for both analog and digital transmission. The bandwidth depends on the thickness of wire and
the distance travelled. Twisted pairs are generally limited in distance, bandwidth and data rate.
3. Optical Fiber: In optical fiber light is used to send data. In general terms presence of light is taken
as bit 1 and its absence as bit 0. Optical fiber consists of inner core of either glass or plastic. Core is
surrounded by cladding of the same material but of different refractive index. This cladding is
surrounded by a plastic jacket which prevents optical fiber from electromagnetic interference and
harshly environments. It uses the principle of total internal reflection to transfer data over optical
fibers. Optical fiber is much better in bandwidth as compared to copper wire, since there is hardly
any attenuation or electromagnetic interference in optical wires. Hence there is fewer requirements
to improve quality of signal, in long distance transmission. Disadvantage of optical fiber is that end
points are fairly expensive. (eg. switches)
Differences between different kinds of optical fibers:
1. Depending on material
 Made of glass
 Made of plastic.
2. Depending on radius
 Thin optical fiber
 Thick optical fiber
3. Depending on light source
 LED (for low bandwidth)
 Injection lased diode (for high bandwidth)
Wireless Transmission
1. Radio: Radio is a general term that is used for any kind of frequency. But higher frequencies are
usually termed as microwave and the lower frequency band comes under radio frequency. There
are many application of radio. For eg. cordless keyboard, wireless LAN, wireless Ethernet. but it is
limited in range to only a few hundred meters. Depending on frequency radio offers different
2. Terrestrial microwave: In terrestrial microwave two antennas are used for communication. A
focused beam emerges from an antenna and is received by the other antenna, provided that
antennas should be facing each other with no obstacle in between. For this reason antennas are
situated on high towers. Due to curvature of earth terrestrial microwave can be used for long
distance communication with high bandwidth. Telecom department is also using this for long
distance communication. An advantage of wireless communication is that it is not required to lay
3. Satellite communication: Satellite acts as a switch in sky. On earth
VSAT(Very Small Aperture Terminal) are used to transmit and receive
data from satellite. Generally one station on earth transmits signal to
satellite and it is received by many stations on earth. Satellite
communication is generally used in those places where it is very difficult
to obtain line of sight i.e. in highly irregular terrestrial regions. In terms
of noise wireless media is not as good as the wired media. There are
frequency band in wireless communication and two stations should not
be allowed to transmit simultaneously in a frequency band. The most promising advantage of
satellite is broadcasting. If satellites are used for point to point communication then they are
expensive as compared to wired media.
Network Devices
Router is intelligent device which routes data to destination computers. It helps in connecting two different
logical and physical networks together. In small network server is connected to router along with clients for
communication. With routers network communication is not possible; it is soul of
network without which distribution if internet and other network data to entire network
is impossible. It works very same when it comes to use wireless network using
wireless network router. It performs all functions similarly without using any medium
like cables etc. Router uses software known as routing table. Routing table is used to
store source and destination address. Major companies which know for manufacturing
routers and wireless routers are Tp Link, Cisco systems, Nortel, D link etc.
If we talk about networks on larger scale hub(s) are required to build network. All
computers are connected directly to the hub as hub performs as centralized
device the network. When data is sent to the hub it broadcasts the data to all the
ports of the hub and then it is sent to destination computer on the network. If hubs
fails to perform its routine functions it will halt the working of the entire network
until it is put back in normal condition.
Switch is another important device when we talk about computer network on broader spectrum. It is used at
the same place as hub is but the only difference between the two is that switch possess switching table with
in it. Switching tables store the MAC addresses of every computer it is connected to and send the data to
only requested address unlike hub which broadcasts the data too all the ports. Switches can be considered
advance form of hubs.
Communication Connectivity
Digital Subscriber Line (DSL) technologies, often grouped and connect a computers to the Internet. DSL use
existing copper pair phone line wiring in conjunction with special hardware switch which is used at the ends
of the line.
Since the connection is digital, DSL technology doesn‟t have a digital-to-analog conversion like traditional
modems. It eludes voice audio spectrum frequency boundaries because it can use frequency above the
voice audio spectrum. This means we can use our phone while maintain our internet connection.
Advantages of DSL
DSL is more cost-effective because it eliminates the need for extensive and expensive infrastructure
 DSL service requires no new phone lines.
 Easy to used, and requires no additional training.
 The fastest solution available for timework programs.
Dial-up Internet Access is a form of Internet access via telephone lines. The user‟s computer or router uses
an attached modem connected to a telephone line to dial into and internet service provider‟s(ISP) node to
establish a modem to modem link, which is then used to route packets between the user‟s equipment and
hosts on the internet.
Dial-up connections to the internet require no infrastructure other than the telephone network. As telephone
access is widely available, dial up remains useful to travels. Dial up is usually the only choice available for
rural or remote areas where broadband installations are not prevalent due to low population and demand.
Dial up access is a transient connection, because either the user or the ISP terminates the connection.
Internet service provider will often set a limit on connection durations to prevent hogging of access , and will
disconnect the user-requiring reconnection and the costs and delays associated with it.
File Transfer Protocol - FTP
The File Transfer Protocol is an excellent method to transfer (download and send) files from one computer to
the other over the Internet. Though you can transfer files using email, it is not a good choice especially when
the file size is large or when you need to transfer several files. The objectives of FTP are to:
promote file (programs or data) sharing
efficiently transfer data from one computer to another
encourage indirect or implicit use of remote computers
provide a common platform for file storages among different hosts
What is the Internet ?
What is Internet :
The formal definition of INTERNET is an international computer network – but that could be expanded to
include the content too Internet is not a product but a technology. A technology refers to a world wide
communication system that links millions of computers has been developed and this network is called the
Information Superhighway.
Brief History :
In 1969 the US Department of Defence started a network called ARPANET (Advance Research Project
Agency Network).This network was setup by the military to ensure that communications did not break down
in the event of war.
The department of Defence (DOD) wanted to maintain contacts with Military
research & Universities doing military related research. Later, they allowed other universities to join the
network. Every University in the country wanted to become a part of the ARPANET. Then the Network was
divided into two parts.
The MILNET for managing military sites &
The other part of ARPANET for maintaining non-military sites.
Internet Service Provider (ISP) :
To connect to the Internet you will b need someone to allow you to connect into their Computer , which in
turn is connected to another computer. A firm in the business of providing Internet Service Provider.
India‟s International Telecom Carrier, has also contributed its might, to the expansion of Internet
Backbone to India. This back bone in India is known as VSNL‟s Gateway Internet Access Service (GIAS)
TCO/IP Communication Protocol:
TCP/IP is a protocol. A protocol is the basic software or rules, used to control the Internet. This is the basic
software which is responsible for the way data travels from one machine to another across the networks.
The Internet is based on TCO/IP. If you are running Windows‟95/98 you already have the TCP/IP software.
TCP/IP has two major components.
Transmission Control Protocol (TCP)
Internet is a Packet Switching Network, the data to be converted into small packets (Envelopes). TCP
breaks up the data to be sent into little packets. It guarantees that any data sent to the destination computer
reaches it intact. TCP stands for Transmission Control Protocol.
Internet Protocol (IP)
IP is a set of conventions used to pass packets from one host to another. It is responsible for routing the
packets to a desired destination IP address. IP also defines how much data can fit in a single “envelope”
Understanding Domains and IP :
The Internet has more than a million computers attached to it. How do you find out which computer you want
to communicate with?
Very similar to postal address system, Internet addressing is a systematic way to identify people,
computers and the Internet resources. On the Internet the term “address” is used loosely. Address can mean
many different things from an electronic mail address to URL.
It is the IP (Internet Protocol) that is used to keep a track of the millions of users. Each computer on
the network is called a HOST and has a number. The IP addressing system uses the letter addressing
system and the number addressing system. The letter address is a series of word separated by dots.
Usually word abbreviations are used instead of whole words.
Domain Name : A domain name is way to identify and locate computers connected to the Internet. No two
organizations can have the same domain name.
A domain name always contains two or mare components separated by periods, called “dots”. Some
examples of domain names are etc. once a domain name has been registered
“subdomain” names can be created within this domain.for example, the domain name for a large company
could be “” and within this domain, subdomainscan be created for each of the company‟s regional
offices. For example:
The World Wide Web:
The Web is glossy glamorous, user-friendly face of the Internet. A media reach potpourri of virtual shopping
malls, music samples,.online magazines art galleries etc. The World Wide Web is a series of a server that
are interconnected through hypertext. Hypertext is one method in which certainties are highlighted. What
makes the WWW so exciting is that you can go anywhere, for example, an FTP site, or to another
document. In addition the WEB offers another service, a URL formally known as Uniform Resource Locator,
the web address. To visit an address you simply key it into the”URL”. Your browser then opens the page on
the screen. The term home page is also known as index page of any organization or information source.
The WWW provides a network of interactive documents and the software to access them. It is based
on documents called pages that combine text, pictures, forms, sound, animation and hypertext links called
hyperlinks. To navigate the WWW, users “surf” from one page to another by pointing and clicking on the
hyperlinks in text or graphics.
Web Pages:
Web page is a single unit of information, often called a document that is available via the World Wide Web or
W3. A web page can be lunge that one computer screen and can use more than one piece of paper when it
is printed out.
A web page is created using HTML. It consists of standardized codes or “tags” that are used to
define the structure of information on a web page. These codes enable web pages to have many features
including bold text, heading, paragraph breaks and number or bulleted lists.
This is the format used for writing documents to be viewed with a World Wide Web browser. Items in the
document can be text, image sounds, and links to other HTML documents or sites, services and resources
on the Internet.
A HTML document can be created using any text edition. Number of HTML editors is now available in
market. Some of the HTML editors (like coffee cup) are coming free of cost with magazine CDs.
HTML is standardized and portable. A document that has been prepared using HTML markup “tags”
Can be viewed a using a Varity of web browser.
Internet browsing or “net surfing” is the process of visiting then different web sites on the internet hosted by
the various companies. Organization and individual etc.
HTTP stands for HyperText Transfer Protocol. Web Pages are sent and received through HTTP, a
client/server based method used to transfer hypertext file across the Internet.
WEB BROWSING: A web browser is a piece of software that acts an interface between the user and the
inner-working of the Internet, specially the Word Wide Web. Browsers are also
Definitions of email address on the Web:
Email, also sometimes written as e-mail, is simply the shortened form of electronic mail, a protocol for
receiving, sending, and storing electronic messages. Email has gained popularity with the spread of the
Internet. In many cases, email has become the preferred method of communication
An e-mail address identifies a location to which e-mail messages can be delivered. An e-mail address
on the modern Internet looks like, for ...
e-mail address - A unique identifier of the form user [email protected] name specifying a virtual location to
which e-mail can be sent
 An email address provided by Asia Registry in accordance with these Terms of Service.
An email address determines the sender and recipient of a message in electronic
communication. It consists of a local part (before the @ character) and a domain part (after
the @ character). ...
The professional version of Add-A-Form® allows the creator to have the data from each
submission of the form Emailed to the address specified here. If the "Email individual user
data" action type is not selected, then this address will be ignored.
An email address is a string of letters and punctuation marks that identifies a person or
organisation on the internet.
This is the address used for sending emails to a person or an organization. Every email
address is unique and email is stored on mail servers (like a large postbag) until the owner
of the mailbox (email account) retrieves or downloads their emails.
A personal and unique address on the Internet.
e mail address - Identifies a specific e-mail account (username) located at (@) a particular
e mail address - electronic mail - Electronically transmitted messages. Linked by high speed
data connections that cross international boundaries, e-mail lets you ...
e mail address - A string that identifies a user and enables the user to receive Internet
e mail address - means the electronic mail address provided by the User in the Application
which shall be used for identification of the User together with the Application Number in all
matters relating to the relevant Application.
e mail address - This is where electronic mail is received. It is a combination of a user name
and a host name, such as [email protected]
e mail address - Electronic identification that enables users to send and receive electronic
e mail address - A multipart address for electronic mail. E-mail addresses begin with a user
identification followed by a standardized Ï@Ó symbol. The address also contains a host
name. Addresses at larger institutions, such as universities, may also contain a subdomain
name. ...
Concept of OS and Type of OS
OS Stands for Operating System Software. It is system software having master control on the computer
system. This software developed for the machine to make it alive. It is responsible to run the computer & its
different units. It provides a communication media in between the user and computer. User can interact with
computer through OS. This master software is responsible to decode the instruction, which are given by the
user. According to the users instruction OS is able to determines that what kind of task performed by which
unit or device. User is just using the devices but the devices are operated through OS software. All
hardware units and CPU are worked under the control of OS Software. It manages all I/O operations and
It provides a base/ environment on which different software or programs can run under it. It uses like an
Interface in between application software and computer. It acts like a platform to run the software. It have
the master control power on the execution of software.
( Computer )
( Computer )
( Computer )
1.1 Evaluation of OS
Early computers were huge hardware machines operated from a console terminal attached to the computer
for monitoring the status of the computer to run a job. Initially a computer operator was the person who had
known the inside of computer problems. User operate the hardware manually to get the job at that time the
data fed to the system through punch card and tapes into the console. There using the software assembler
for different operations. These systems are quite slow. To increase the efficiency of the system some
development is required. To manage the CPU time and its speeds software is required in between the
computer and user which bridges the operator and the machine. This software is known as Operating
System (OS). The main of OS is to improve the performance of the computer and the make the operation
easier for the operator. OS is the sole of the computer system. When it gets loaded on to the computers
internal memory the system gets live.
1.2 Advantages of OS
1) Operator can use the computer very easily and efficiently.
2) It manages all I/O devices and operations.
3) It bridges the speed of CPU and I/O devices.
4) It manages Memory.
5) It provides the facility time-sharing & job scheduling for multiple users (Multiusers).
6) It provides multitasking and multiprogramming for different application program.
7) It manages and operates all kinds of storage devices.
1.3 Types of OS
There are two types of Operating System.
Single User OS
Multi User OS.
Single User OS
These operating system having capability to maintain limited numbers of peripheral devices. It
supports only one user can work at a time. The single user operating system divided in to two types i,e
CUI and GUI.
CUI (Command User Interface) like MS-DOS, PC-DOS etc.
GUI (Graphical User Interface) like Windows~9x, Win~Me, Win-XP etc.
This OS used for a stand-alone machine. Like Personal Computers.
Multi User OS
This types of OS having capabilities to maintain large numbers of peripheral devices. Its supports more than
one users can work at a time. It uses in the computer network systems like mainframe, LAN etc. It is more
powerful than the single user OS.
CUI (Command User Interface) like UNIX, LINUX etc.
GUI (Graphical User Interface) like Windows NT, Win-2000 etc.
Batch Processing Operating System
In a batch processing operating system interaction between the user and processor is limited or there is no
interaction at all during the execution of work. Data and programs that need to be processed are bundled
and collected as a „batch‟ and executed together.
Batch processing operating systems are ideal in situations where:
- There are large amounts of data to be processed.
- Similar data needs to be processed.
- Similar processing is involved when executing the data.
The system is capable of identifying times when the processor is idle at which time „batches‟ maybe
processed. Processing is all performed automatically without any user intervention.
Real-time Operating System
A real-time operating system processes inputs simultaneously, fast enough to affect the next input or
process. Real-time systems are usually used to control complex systems that require a lot of processing like
machinery and industrial systems.
Multi-Tasking Operating System
In this type of OS several applications maybe simultaneously loaded and used in the memory. While the
processor handles only one application at a particular time it is capable of switching between the
applications effectively to apparently simultaneously execute each application. This type of operating system
is seen everywhere today and is the most common type of OS, the Windows operating system would be an
Distributed Operating System
In a distributed system, software and data maybe distributed around the system, programs and files maybe
stored on different storage devices which are located in different geographical locations and maybe
accessed from different computer terminals.
While we are mostly accustomed to seeing multi-tasking and multi-user operating systems, the other
operating systems are usually used in companies and firms to power special systems.
1.4 Functions of OS
OS work as a Manager, Controller and Command Interpreter. It manages over
all activities of the computer system. OS controls the operations, which are
going in the computer system. It acts like a police station, during the time of
execution of any program & software if any errors occur that reports to OS and
OS is responsible to provide suitable error massage. It also decode the instructions
given by the user. Generally there are four functions of OS.
As a Manager
Process Management
Memory Management
File Management
I/O Management
/ commands which are
Process Management
Creation and termination of processes are the process management tasks of operating system.
Processes are put in a queue when they are entered. OS selects the process from this queue using a
technique called scheduler. All the computer resources have to be scheduled. Scheduling is one of the
fundamental functions of OS. CPU scheduler decides which of the process ready in the queue will be
allocated CPU time. There are several algorithms for CPU scheduler.
 The simplest of these algorithms if First-Come-First-Served (FCFS). In this the process that requests the
CPU first will get the CPU time first.
 Another approach of scheduling is shortest Job First (SJF) where the scheduling of a process is done on
the basis of its having shortest execution time.
 Round Robin scheduling is a widely used algorithm that was design mainly for time sharing systems.
Here the queue is a circular one and the scheduler allocates each process for a pre defined time
 In Priority based scheduling, the scheduler picks up the highest priority process from the queue.
 In Multi Level Queue (MLQ) scheduling, processes are divided into groups and each group has a
different queue. Each queue has its scheduling algorithm suited to the type of process in that particular
As a Controller
Operating system having the master control power to control overall operations of the computer system .It
co-ordinate all software and hardwires. It acts like a police station during the execution of any program or
software if any error occur at this time .the control will switch bass acts operating system and operating
system is responsible for defects the error and provide suitable error message .It also acts like application
program interface .It is the interface in between the hardware and user to run different programs and
software‟s. it control the signal whether the data being write in to read from the memory.
As a Command Interpreter
The command or instruction which are given by the user. Operating system is responsible to read it and
decode the instruction operating system known to execute .The requested command or instruction , What
kind of task and operating have to perform by which unit or command one defined in as.
OS uses Different Disk Areas
Disk Contains number of tracks & sectors. Data and Information are recorded in the secondary memory as a
track wise and sector wise. Different disk having different number of tracks and sectors. Tracks and sectors
are numbered, the numbering starts from 0(Zero)
The whole area of the disk divided into 4 areas.
1. Boot Sector Area
2. FAT (File Allocation Table)
3. Root Directory
4. Data Area
Boot sector area
It is the initial area of the disk. The 0th number track and 0th number sector is known as boot sector
area. This area contains a program i.e BootStrap Loader Program. This area makes the disk bootable.
FAT (File Allocation Table)
FAT stands for File Allocation Table. It is just like a index table which contains the indexes of files.
Which are stored in the disk. This area is known as heart of the disk.
In the disk the data written in a random order, where at gets the free space, I write he data on that area
without checking the size of file and the capacity of the area.
In the disk the data‟s are read and write through a head that is known as Read Write head. For reading
and writing both head and disk are in moveable condition.
The movement of disk is known as Rotational and the movement of head two or fro. By movement of
head tracks are changed and by movement of disk sectors are changed.
The 0th number sectors and 1st track is known as FAT area.
Root Directory
FAT followed by the root directory. It is the initial or main directory of the disk. It presents the whole data
area of the disk. It is always unique. User cannot create or delete the root directory by using the command
MD and DELTREE. It automatically creates at the time of formation of the disk.
Data Area
This area is used to sore the data or information of the file. It provides the free space for the data and the
addresses of the disk area are recorded in the FAT.
File System in FAT,FAT16,FAT32,NTFS
The precise manner in which data is organised on a hard disk drive is determined by the file system used.
File systems are generally operating system dependent. However, since it is the most widely used PC
operating system, most other operating systems‟ file systems are at least read-compatible with Microsoft
The FAT file system was first introduced in the days of MS-DOS way back in 1981. The purpose of the File
Allocation Table is to provide the mapping between clusters – the basic unit of logical storage on a disk at
the operating system level – and the physical location of data in terms of cylinders, tracks and sectors – the
form of addressing used by the drive‟s hardware controller.
The FAT contains an entry for every file stored on the volume that contains the address of the file‟s starting
cluster. Each cluster contains a pointer to the next cluster in the file, or an end-of-file indicator at (0xFFFF),
which indicates that this cluster is the end of the file. The diagram shows three files: File1.txt uses three
clusters, File2.txt is a fragmented file that requires three clusters and File3.txt fits in one cluster. In each
case, the file allocation table entry points to the first cluster of the file.
The File Allocation Table (FAT) file system is a simple file system originally designed for small
disks and simple folder structures. The FAT file system is named for its method of organization,
the file allocation table, which resides at the beginning of the volume. To protect the volume, two
copies of the table are kept, in case one becomes damaged. In addition, the file allocation tables
and the root folder must be stored in a fixed location so that the files needed to start the system
can be correctly located.
A volume formatted with the FAT file system is allocated in clusters. The default cluster size is
determined by the size of the volume. For the FAT file system, the cluster number must fit in 16
bits and must be a power of two.
Structure of a FAT Volume
The figure below illustrates how the FAT file system organizes a volume.
Figure 4-1
The first incarnation of FAT was known as FAT12, which supported a maximum partition size of 8MB. This
was superseded in 1984 by FAT16, which increased the maximum partition size to 2GB. FAT16 has
undergone a number of minor modifications over the years, for example, enabling it to handle file names
longer than the original limitation of 8.3 characters. FAT16′s principal limitation is that it imposes a fixed
maximum number of clusters per partition, meaning that the bigger the hard disk, the bigger the cluster size
and the more unusable space on the drive. The biggest advantage of FAT16 is that it is compatible across a
wide variety of operating systems, including Windows 95/98/Me, OS/2, Linux and some versions of UNIX.
Dating from the Windows 95 OEM Service Release 2 (OSR2), Windows has supported both FAT16 and
FAT32. The latter is little more than an extension of the original FAT16 file system that provides for a much
larger number of clusters per partition. As such, it offers greatly improved disk utilisation over FAT16.
However, FAT32 shares all of the other limitations of FAT16 plus the additional one that many non-Windows
operating systems that are FAT16-compatible will not work with FAT32. This makes FAT32 inappropriate for
dual-boot environments, although while other operating systems such as Windows NT can‟t directly read a
FAT32 partition, they can read it across the network. It‟s no problem, therefore, to share information stored
on a FAT32 partition with other computers on a network that are running older versions of Windows.
With the advent of Windows XP in October 2001, support was extended to include the NTFS. NTFS is a
completely different file system from FAT that was introduced with first version of Windows NT in 1993.
Designed to address many of FAT‟s deficiencies, it provides for greatly increased privacy and security. The
Home edition of Windows XP allows users to keep their information private to themselves, while the
Professional version supports access control and encryption of individual files and folders. The file system is
inherently more resilient than FAT, being less likely to suffer damage in the event of a system crash and it
being more likely that any damage is recoverable via the chkdsk.exe utility. NTFS also journalises all file
changes, so as to allow the system to be rolled back to an earlier, working state in the event of some
catastrophic problem rendering the system inoperable.
FAT16, FAT32 and NTFS each use different cluster sizes depending on the size of the volume, and each file
system has a maximum number of clusters it can support. The smaller the cluster size, the more efficiently a
disk stores information because unused space within a cluster cannot be used by other files; the more
clusters supported, the larger the volumes or partitions that can be created.
The table below provides a comparison of volume and default cluster sizes for the different Windows file
systems still commonly in use:
Volume Size
7MB – 16MB
17MB – 32MB
33MB – 64MB
65MB – 128MB
129MB – 256MB
257MB – 512MB
Cluster Size Cluster Size Cluster Size
512 bytes
Not supported
Not supported
512 bytes
512 bytes
512 bytes
512 bytes
512 bytes
512 bytes
512 bytes
513MB – 1GB
1GB – 2GB
2GB – 4GB
4GB – 8GB
8GB – 16GB
16GB – 32GB
32GB – 2TB
Not supported
Not supported
Not supported
Not supported
Not supported
DOS in short stands for Disk Operating System. In other words, the operating system is available in on the
disk (floppy disk). This DOS controls and manages the way the computer uses programs and data, making it
easier for the user to use them for application. It also allows the user to use the devices; Disk drives, Printer,
Screen etc. Therefore, it is essential that, DOS remains active in the memory (RAM) from the time the
computer is switched ON, till it is put OFF, and for that, it needs to be copied from the DOS diskette to the
RAM. This process of loading the DOS from the disk to RAM is called Booting, discussed below.
Field of Application
- booting system for storage media
- File management
- For single user systems only
- Network client (NetBEUI, IPX/SPX, TCP/IP)
- batch processing
Structure information
- 16-bit operating system, (formerly 8-bit)
- Single tasking
- command interpreter for internal and external commands
- external driver software imbedding for periphery devices possible
System environment
- minimum: 512 kbytes RAM, 5 mbyte harddisk storage (depends on version for full installation)
- FAT file system
- executable with every x86 compatible CPU
- low RAM and fixed storage disk needs
System Files of Ms-Dos
Ms- dos consist of three system files IO.SYS, MSD OS.SYS, COMMAND.COM. These three files are
responsible to create a communication, manage devices & interpret the command.
IO.SYS (Input Output System Files): these files consist two modules SYSINIT & Disk Bios. SYSINIT module
is responsible to initialization the system. And Disk Bios consist the device drivers for the standard I/O
Device Driver is a program, which is responsible to drive the device. Each device having its own drivers
Programs. It differs device to device and company to company.
MSDOS.SYS (Kernel of OS) It is the heart of the OS. Kernel is the collection of the hardware independent
services called system function. It also acts like a File & Disk Manager. It reads the files & Directory names
from the disk.
COMMAND.COM(shell of OS) it is the shell of the Ms-Dos. It is the core part of OS. It consists of two
modules Resident & Transient.
Resident portion of Ms-Dos is responsible to manage / handle the errors and provides the suitable error
messages. It also handles the critical errors during the period of execution of High Level Program.
Transient portion of COMMAND.COM contains instructions for executing the commands. It acts like a
command Interpreter. Sum sets of commands are resides in this portion that are used as a Internal
commands. The Transients portions decode the instructions and determine which part or unit will work for
Booting is the process of loading the Operating System from the secondary memory to primary memory.
This process starts immediately just after switch on the computer. When computer is switched on ROM gets
activate and program BIOS program that resides in ROM starts execution.
The entire booting process follows these sequences of steps:
The power source to the computer switched ON
The BIOS (Basic Input Output System) program present in the ROM is activated .
While BOOTing the system, secondary storage device from where the IO.SYS, MSDOS.SYS and
Command.Com is loaded is referred to as BOOT disk. The first floppy drive in the system is generally
referred to as drive A and second drive as drive B. The HARD disk drive of the system is always referred as
drive C. Depending on the boot disk used, the system at the end of the booting prompts the user either
A:\> or C:\> which is called either A prompt or C prompt.
So the boot disk or SYSTEM DISK should have the following files:
Files :- Data / information are stored onto the disk permanently inform of File. It is collection of data and
information. The resident of the file is secondary memory. For the identification of files each and every files
having a unique name File Name. File name consist of two names
Primary name (Maximum 8 Characters can be used. ) <Primary name >[.<Extension name>]
Extension Name (Maximum 3 characters can be used. )
Both names are separated by a Dot (.). The name, which is used before the dot, is Primary name and after
dot name is Extension name. Extension name is the optional name. No blank space or special symbol can
be used for naming the files. Files name must starts with a character.
There are two type of files
Text File
Command file
Text File contains the data or information in secondary memory for the future use. Any extension name can
be used for these files.
Command files contain the instructions to accomplish a task. It is an executable file. The command files
uses the extension name .COM, .EXE,.BAT
. COM Command files
. EXE Executable files
. BAT Batch files
A directory on a disk likes a table of content in books. It contains name of the files, size of files, date & time
of creation or last access. It is a logical table, which keeps track of the accessing of files. Directories are
used to manage the different types of files. Files are stored under the directory. Directory is also identified
through a name as like file name.
Disk Derive :- A computer system may attached with more one storage device. OS software uses derives
for different storage device and OS gives name to each derives i.e derive name. Derive name is the logical
name given OS (Ms-Dos) to identify the disk derive.
For floppy disk A: or B:
For Hard Disk C:
<drive letter > :
For CD-ROM D: E:, ….
The mechanism, which pays the disk, are named and identified by the OS itself.
Ms-Dos Prompt: - It is a symbol which appears on to the screen and it indicates that now the computer is
ready to execute the instruction (Commands). All commands must be typed at the Dos Prompt for execution.
This symbol gives the information of about the current drive, current directory. After booting the command
prompt automatically appears on to the screen.
The line or row at which this symbol appears known as command line /row. Which supports only one
command at a time. After the prompt it provides the cursor for typing of commands. Cursor is horizontal
blinking bar which indicates the current position of the screen.
Command is an instruction, which tells to computer to perform a task or an operation. Each command is
having its own syntax for its execution. Ms-dos provides various commands for various operations. Syntax is
the way executing the commands. In syntax the <> & [] are used.
 < > Indicates that parameter which compulsory & [ ] indicates that options which are optional.
 All commands should be typed at the DOS Prompt
 Commands should be typed according to Dos Prompt.
There are two types of command 1. Internal Command
2. External command
Internal Command is the memory resident commands. It directly executes from the primary memory. It
loads on to the memory at time of booting and it resides on it as long as user in Dos. The execution of the
internal commands are faster.
How to Open MS-DOS Command Prompt
Step 1. Overview:
Run cmd.exe or command.exe
To open a Microsoft MS-DOS command prompt shell window, first click the Windows Start menu (located at
the very lower-left corner of your computer's desktop) and select "Run...".
Then if you are using Windows XP or Vista or Windows 7, type cmd into the Run box and click "OK". You
could also type cmd.exe
Otherwise, if you are using an older version of Windows, type command into the Run box and click "OK".
You could also type command.exe
Step 2. The Window:
After you click "OK", an MS-DOS command prompt window will appear. Depending upon which version of
Windows you are using, the MS-DOS command window will look similar to these images:
Step 3. Text/Background Colors:
The standard window displays white text on a black background. This color combination may make text
difficult to read. To make the window display black text on a white background, type the command: color f0
(that's the letter f followed by the digit zero 0). To go back to the standard of white text on a black
background, type: color
Step 4. MS-DOS Commands:
See the MS-DOS Commands index for a description of the commands that you can type into the MS-DOS
command prompt window. The most common tasks are:
Copy con command ,Save the file ,Type command,,Cls command, Edit command
,Dir command ,Change directory (cd) ,Make a directory (md) ,Cd.. command ,Tree
command ,Copy a file (copy) ,Delete a file (del) ,Date command ,Time command ,
Rename command , Move command ,Attrib command ,Remove directory(RD)
To close the window, either type exit and press Enter, or click the X button in the top-right of the window
copy con command is a command which is create a new file
for example –copy con <file name>
save the file –save the craeat a new file we are used F6 or ctrl+z
MS-DOS Commands :: type
Use the type command to display the contents of a file.
Command Variations:
type filename
Displays on the screen the contents of the file named filename. For example, "type mystuff.txt" displays the
contents of the file mystuff.txt located in the current directory.
If you want to display a file that is in a directory other than the current directory, then use the "cd" command
first or include the directory name, such as: "type \mystuff\ebooks\list.txt".
Note: If the contents of the file is more than one screenful, then you should use the "more" command
instead otherwise the text will scroll off the top of the window without stopping.
help type
Displays the contents of a text file or files.
TYPE [drive:][path]filename
MS-DOS Commands :: CLS
When you are using a Microsoft MS-DOS command prompt shell window, you can type cls to clear the
window and move the command prompt to the top of the window.
No files are changed by the cls command.
The window display is merely cleared.
MS-DOS Commands :: EDIT (MS-DOS Editor)
Note: If Windows is running then use notepad instead since it is easier to use than edit. See: notepad.
Type edit at the command prompt and the MS-DOS text editor program will be run. The editor is a text editor
that uses a simplistic window and menu system inside an MS-DOS window.
Even though the edit program was designed for MS-DOS (a text based environment), it does recognize the
mouse. You can use the mouse to select commands and to move the cursor (which appears as an
underline). Although the program is archaic compared to today's interface standards, anyone familiar with
Windows should be able to use the program.
Since the edit program was originally designed for use in the text based user interface of MS-DOS rather
than in the graphic interface of modern computers, the window automatically resizes to 80-characters wide.
The window is locked at this size and cannot be resized. If you view a file that has lines wider than 78
characters (2 characters are used for the "border"), you can scroll horizontally by using the
left/right/Home/End arrow keys. Unfortunately, there is no horizontal scroll bar. There is a vertical scroll bar
and you can use the up/down/PgUp/PgDown arrow keys.
The edit program has menus similar to what appear in modern Windows programs:
File: New, Open..., Save, Save As..., Close, Print..., Exit
Edit: Cut, Copy, Paste, Clear
Search: Find..., Repeat Last Find, Replace...
View: Split Window, Size Window, Close Window
Options: Settings..., Colors...
Help: Commands..., About...
Commands can be selected by the mouse or by keyboard. As with a modern Windows application, menus
can be accessed by keyboard by pressing the Alt key and the first letter of the menu title (i.e.: Alt-F, Alt-E,
Alt-S, Alt-V, Alt-O, Alt-H). Once a menu is visible, use the arrow keys to move the highlight, and pres Enter
key to select.
Command Variations:
Runs the editor and starts with a blank document. When you select Save or Save As..., the file will be saved
to the current directory (unless you select otherwise from the popup dialog). If you want to select a different
directory before starting edit, use the cd command before using edit.
edit filename
This command will cause the file named filename to be opened by the edit editor. For example, edit mylist.txt
would open the mylist.txt file. If the file filename does not exist, the editor will start with a blank document
with that name (no file is created until you select Save or Save As...).
If you want to edit a file that is in a directory other than the current directory, then use the "cd directory"
command first or specify the directory name as part of the filename, such as: "edit \mystuff\ebooks\list.txt". If
the filename contains spaces, enclose the entire filename in quotation marks, such as: edit "\mystuff\my
help edit
There is no built-in help for the edit command. The program uses a simplistic window and menu system that
is fairly easy to understand for any person who has experience using Windows.
Related Commands:
To run the Windows Notepad text editor, use the notepad command. The Windows Notepad editor is a
modern Windows application that is much easier to use than edit.
DIR command :- Use the dir command to display a listing of the contents of the current directory.
Information about the files and subdirectories of the current directory will be displayed.
Command Variations:
dir directory
By specifying a directory, the contents of that directory is displayed. For example, dir \mystuff will display the
contents of the \mystuff directory. Note: If directory contains a space, then type quotation marks around the
directory name; for example, dir "c:\program files"
dir > myfiles.txt
Will save a list of all files contained in the current directory to the file myfiles.txt. You can use >filename at
the end of any command to cause that command's output to be written to the file specified.
Tip: You can use the clip command to save the directory listing to the Windows clipboard, such as: dir | clip
Tip: If you want to save a list of files and their properties (e.g.: file size, last modified date) to a .csv
spreadsheet file, try using the filelist utility.
dir *.txt
Displays a listing of all the .txt files located in the current (or specified) directory.
dir my*
Displays a listing of all files that start with the pattern you specify; in this example, "my".
Command Options:
There are a few options you can use with the dir command. For the complet list of options, type dir /? or help
Position of options: If you specify a directory as part of the command, options can be specified before or
after directory
Multipel options: You can type more then one option at the same time. For example, dir /p/w \mystuff would
display a wide listing of the \mystuff directory and pause after each screenful.
The following examples demonstrate some of the more useful options:
dir /p
Pause the directory listing after every screenful. To continue the listing, press any key (e.g.: spacebar or
Enter key).
dir /o:gne
Displays a directory listing that is sorted. You specify the sort order by one or more letter after the /o: part.
The most useful sort order is gne which puts all the subdirectories before files (g), and sorts by name (n),
and then by filename ending (e).
Tip: You can set the sort order (remains in effect until you close the MS-DOS window) by typing a set
command, such as: set dircmd=/o:gne
dir /o:s
Displays a directory listing that is sorted by size (smallest to largest). To reverse the sort order (largest size
to smallest size), prefix the sort order with a - (minus sign): dir /o:-s
dir /o:d
Displays a directory listing that is sorted by date/time (oldest to newest; oldest at top, newest at bottom). To
reverse the sort order (newest to oldest; newest at top, oldest at bottom), prefix the sort order with a - (minus
sign): dir /o:-d
dir /s
Displays the contents of the current directory (or specified directory) as well as the contents of all
subdirectories and their subdirectories too. Since the output can be very long, especially if you have
subdirectories inside subdirectories, you probably should also use the /p option to pause output. If you forget
to do that, you'll probably see the output zipping by on your screen; in that case, press Ctrl-C to stop the
command. Or you might want to save the output to a text file, for example: dir /s > myfiles.txt will output a
list of all files contained in the current directory and all subdirectories to the file myfiles.txt
dir /s *.txt
Displays a listing of all .txt files located in the current directory and in all subdirectories.
dir /s mystuff.txt
Displays a listing of all instances of a file named mystuff.txt located in the current directory and in all
subdirectories. Useful when you know the name of a file but don't recall which subdirectory it is located in.
You can think of this command as the equivalent of the Windows Search Companion (accessible by
pressing F3 when viewing a Windows folder).
dir /w
Wide directory listing.
dir /b
Displays a directory listing showing just the filenames without header information or file size/date. This bare
format is useful when you just want the actual filenames and you're going to do some sort of further
processing. For example dir /b /s \mystuff > files.txt would create a file named files.txt that contains just
the filenames of files located in the \mystuff directory and all its subdirectories.
dir /ah
Displays a listing of hidden files (if any) that are located in the directory. Tip: Use the attrib command to
change the hidden attribute of a file.
help dir
Displays a list of files and subdirectories in a directory.
DIR [drive:][path][filename] [/A[[:]attributes]] [/B] [/C] [/D] [/L] [/N]
[/O[[:]sortorder]] [/P] [/Q] [/S] [/T[[:]timefield]] [/W] [/X] [/4]
Specifies drive, directory, and/or files to list.
Displays files with specified attributes.
attributes D Directories
R Read-only files
H Hidden files
A Files ready for archiving
S System files
- Prefix meaning not
Uses bare format (no heading information or summary).
Display the thousand separator in file sizes. This is the
default. Use /-C to disable display of separator.
Same as wide but files are list sorted by column.
Uses lowercase.
New long list format where filenames are on the far right.
List by files in sorted order.
sortorder N By name (alphabetic)
S By size (smallest first)
E By extension (alphabetic) D By date/time (oldest first)
G Group directories first - Prefix to reverse order
Pauses after each screenful of information.
Display the owner of the file.
Displays files in specified directory and all subdirectories.
Controls which time field displayed or used for sorting
timefield C Creation
A Last Access
W Last Written
Uses wide list format.
This displays the short names generated for non-8dot3 file
names. The format is that of /N with the short name inserted
before the long name. If no short name is present, blanks are
displayed in its place.
Displays four-digit years
Switches may be preset in the DIRCMD environment variable. Override
preset switches by prefixing any switch with - (hyphen)--for example, /-W.
MS-DOS Commands :: CD (change directory)
When you are using a Microsoft MS-DOS command window, MS-DOS works on one directory at a time. The
"current" directory is indicated as part of the command prompt.
For example, the command prompt "C:\mystuff\ebooks>" means that the current directory is the "ebooks"
directory which is located inside the "mystuff" directory on the c: drive.
Use the cd command to make a different directory the "current" directory ("cd" is short for "change
The command can be typed as either:
For example, "cd \mystuff" will make "\mystuff" the current directory. To get to the "root" (top level directory)
of your c: drive, type cd \
If directory contains spaces, then enclose it with quotation marks. For example: cd "C:\Documents and
Settings\CCC\My Documents\My Music" or cd "My Music"
Command Variations:
cd directory
cd drive:directory
Make the specified directory directory (or drive:directory) the current directory.
The directory can start with a \ or be relative to the current directory. For example, if the current directory is
C:\mystuff then typing cd ebooks will change the current directory to C:\mystuff\ebooks (assuming that there
is in fact a ebooks sub-directory inside C:\mystuff).
Note: Each drive (c:, d:, e:, etc.) has its own current directory. That's why there is the drive:directory variation
of the cd command. For example: cd e:\photos will set the current directory of the e: drive to \photos. To
switch to the e: drive, you would simply type e: and press the Enter key.
cd /d drive:directory
Make the specified directory directory the current directory and also switch do the drive: drive.
Tip: To make cd always do /d without you having to type it, create a command macro named cd by typing:
doskey cd = cd /d $*
cd ..
You can also type cd .. (the two dots are required) to back out one level out of the current directory. For
example, if the current directory is C:\mystuff\ebooks then typing cd .. will change the current directory to
If you type cd without specifying a directory, the cd command will display the directory path of the current
directory. Typically you will not use this variation of the cd command since the directory path is shown in the
command prompt. It is more useful in batch files.
help cd
Displays the name of or changes the current directory.
CHDIR [/D] [drive:][path]
CHDIR [..]
CD [/D] [drive:][path]
CD [..]
.. Specifies that you want to change to the parent directory.
Type CD drive: to display the current directory in the specified drive.
Type CD without parameters to display the current drive and directory.
Use the /D switch to change current drive in addition to changing current
directory for a drive.
If Command Extensions are enabled CHDIR changes as follows:
The current directory string is converted to use the same case as
the on disk names. So CD C:\TEMP would actually set the current
directory to C:\Temp if that is the case on disk.
CHDIR command does not treat spaces as delimiters, so it is possible to
CD into a subdirectory name that contains a space without surrounding
the name with quotes. For example:
cd \winnt\profiles\username\programs\start menu
is the same as:
cd "\winnt\profiles\username\programs\start menu"
which is what you would have to type if extensions were disabled.
MS-DOS Commands :: md (mkdir)
Creates a directory.
The command mkdir is the same as the md command; they do the same thing. You can use either the mkdir
command or use the md command which takes fewer characters to type.
md /?
Creates a directory.
MKDIR [drive:]path
MD [drive:]path
If Command Extensions are enabled MKDIR changes as follows:
MKDIR creates any intermediate directories in the path, if needed.
For example, assume \a does not exist then:
which is what you would have to type if extensions were disabled.
Cd.. is a command it is used to close of the sub directory and main directory
For example:- C:\mohan\rajesh>cd..
MS-DOS Commands :: tree
Graphically displays the directory structure of a drive or directory.
Tip: You can save the directory tree listing to a file by using tree > filename such as tree > mytree.txt
Tip: You can use the clip command to save the directory tree listing to the Windows clipboard, such as: tree |
help tree
Graphically displays the folder structure of a drive or path.
TREE [drive:][path] [/F] [/A]
/F Display the names of the files in each folder.
/A Use ASCII instead of extended characters.
Copies one or more files to another location. See also: xcopy
help copy
Copies one or more files to another location.
COPY [/D] [/V] [/N] [/Y | /-Y] [/Z] [/A | /B ] source [/A | /B]
[+ source [/A | /B] [+ ...]] [destination [/A | /B]]
Specifies the file or files to be copied.
Indicates an ASCII text file.
Indicates a binary file.
Allow the destination file to be created decrypted
destination Specifies the directory and/or filename for the new file(s).
Verifies that new files are written correctly.
Uses short filename, if available, when copying a file with a
non-8dot3 name.
Suppresses prompting to confirm you want to overwrite an
existing destination file.
Causes prompting to confirm you want to overwrite an
existing destination file.
Copies networked files in restartable mode.
The switch /Y may be preset in the COPYCMD environment variable.
This may be overridden with /-Y on the command line. Default is
to prompt on overwrites unless COPY command is being executed from
within a batch script.
To append files, specify a single file for destination, but multiple files
for source (using wildcards or file1+file2+file3 format).
Deletes one or more files. The specified file (or files) is deleted immediately deleted without any
Tip: It is recommended that you delete files using Windows rather than MS-DOS. If you do use the del
command, it is recommeded that you use the /p parameter so that a confirmation prompt is displayed before
doing the deletion, such as: del /? *.txt
Danger: Do not delete anything unless you know exactly what you are doing. MS-DOS does not have a
"Recycle Bin" so you cannot recover files deleted with the "del" command.
Danger: The character * (an asterisk) is the wildcard character and allows you to delete all matching files by
using one command, such as "del *.tmp" deletes all files that end with ".tmp" in their filename. All matching
files are immediately deleted without any confirmation and cannot be recovered.
Danger: It is extremely dangerous to use "del *" since that would delete everything in the directory. In this
one case, MS-DOS realizes the danger and prompts you to confirm.
help del
Deletes one or more files.
DEL [/P] [/F] [/S] [/Q] [/A[[:]attributes]] names
ERASE [/P] [/F] [/S] [/Q] [/A[[:]attributes]] names
Specifies a list of one or more files or directories.
Wildcards may be used to delete multiple files. If a
directory is specified, all files within the directory
will be deleted.
Prompts for confirmation before deleting each file.
Force deleting of read-only files.
Delete specified files from all subdirectories.
Quiet mode, do not ask if ok to delete on global wildcard
Selects files to delete based on attributes
attributes R Read-only files
S System files
H Hidden files
A Files ready for archiving
- Prefix meaning not
If Command Extensions are enabled DEL and ERASE change as follows:
The display semantics of the /S switch are reversed in that it shows
you only the files that are deleted, not the ones it could not find.
Displays or sets the computer's date. See also: time
Tip: If you want to set your computer's internal clock, it is recommended that you do that task via the Date
and Time Control Panel (Start > Settings > Control Panel > Date and Time).
help date
Displays or sets the date.
DATE [/T | date]
Type DATE without parameters to display the current date setting and
a prompt for a new one. Press ENTER to keep the same date.
If Command Extensions are enabled the DATE command supports
the /T switch which tells the command to just output the
current date, without prompting for a new date.
Displays or sets the computer's time. See also: date
Tip: If you want to set your computer's internal clock, it is recommended that you do that task via the Date
and Time Control Panel (Start > Settings > Control Panel > Date and Time).
help time
Displays or sets the system time.
TIME [/T | time]
Type TIME with no parameters to display the current time setting and a prompt
for a new one. Press ENTER to keep the same time.
If Command Extensions are enabled the TIME command supports
the /T switch which tells the command to just output the
current time, without prompting for a new time.
MS-DOS Commands :: time
Displays or sets the computer's time. See also: date
Tip: If you want to set your computer's internal clock, it is recommended that you do that task via the Date
and Time Control Panel (Start > Settings > Control Panel > Date and Time).
help time
Displays or sets the system time.
TIME [/T | time]
Type TIME with no parameters to display the current time setting and a prompt
for a new one. Press ENTER to keep the same time.
If Command Extensions are enabled the TIME command supports
the /T switch which tells the command to just output the
current time, without prompting for a new time.
Renames a file or files.
help ren
Renames a file or files.
RENAME [drive:][path]filename1 filename2.
REN [drive:][path]filename1 filename2.
Note that you cannot specify a new drive or path for your destination file.
(Enlarge: help ren)
MS-DOS Commands :: attrib
Displays or changes file attributes.
Quick Guide:
Hide/Unhide a Directory:
attrib -h directory
Display attributes of all the files in the current directory or of only the specified file.
For the specified file, either sets (+) or clears (-) the specified a attribute:
Multiple attributes can be specified at the same time, all as part of one a command. The order of the
attributes does not matter. For example, to simultaneously clear the hidden attribute and set the read-only
attribute of the file , use: attrib -h +r mystuff.txt
Command Options:
The following examples demonstrate some of the more useful options of the command. For the complet list
of options, type a or hHide/Unhide a Directory: example, if is hidden then type: to unhide it.
To reverse the change and make the directory hidden, type: attrib +h c:\mystuff\secret\
Hide/Unhide a File:
attrib -h filename
For example, if c is hidden then type:.txt to unhide it.
To reverse the change and make the file hidden, type: attrib +h c:\mystuff\secret.txt
help attrib
Displays or changes file attributes.
ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [drive:][path][filename]
[/S [/D]]
+ Sets an attribute.
- Clears an attribute.
R Read-only file attribute.
A Archive file attribute.
S System file attribute.
H Hidden file attribute.
Attribute Meaning
Specifies a file or files for attrib to process.
/S Processes matching files in the current folder
and all subfolders.
/D Processes folders as well.
MS-DOS Commands :: rd (rmdir)
Removes a directory.
The command rmdir is the same as the rd command; they do the same thing. You can use either the
rmdir command or use the rd command which takes fewer characters to type.
help rd
Removes (deletes) a directory.
RMDIR [/S] [/Q] [drive:]path
RD [/S] [/Q] [drive:]path
Removes all directories and files in the specified directory
in addition to the directory itself. Used to remove a directory
Quiet mode, do not ask if ok to remove a directory tree with /S
Changing of drive:-type the drive latter with colon (:) to change the drive for example: - c:\>d:
PATH Command Displays or sets a search path for executable/ command files.
PATH [[drive:] path [;...]]
Type PATH; to clear all search-path settings and direct Windows to search only in the current directory.
Type PATH without parameters to display the current path. Multiple paths can be specified by using
VOL Command displays the disk volume label and serial number, if they exist.
VOL [drive:]
RENAME Command renames a file/directory or files/directories.
RENAME [drive:][path][directoryname1 | filename1] [directoryname2 | filename2]
REN [drive:][path][directoryname1 | filename1] [directoryname2 | filename2]
Difference Between Internal & External Command
Internal commands are functions that are built into the command interpreter, External commands are
those not included in the interpreter, and are instead invoked by calling an external binary. Whether or
not a particular command is internal or external varies by system. For example, echo is an internal
command in MS-DOS (it is built into COMMAND.COM), while in most Linux systems, it is an external one,
provided by GNU core utils.
DOS Internal command is associated with his Shell file Command.Com.. DOS external command is saved
on the disk..
Create the directory by using MD & CD command.
Create two subdirectories under peripheral that is Input & Output.
Your current directory is peripheral, create a file & a sub directory under application.
Your current directory is CPU, rename the file which create under application.
Current directory is peripheral, create a file under directory DOS.
Create a file under CPU [current directory is Hardware].
Create two sub directories under system software DOS & WINDOW current directory is CPU.
Create three sub directories ALU, CU, Memory under CPU current directory is system
9. Change directory to software as current directory.
10. Create two files under input & output.
11. Create same structure without using CD command by using path.
12. Current directory is CPU, create a file under application.
13. Current directory is Hardware, display the directory structure of software.
Concept Of UNIX Operating System
UNIX is a computer operating system.
An operating system is the program that controls all the other parts of a computer system, both the
hardware and the software. It allocates the computer's resources and schedules tasks. It allows you
to make use of the facilities provided by the system. Every computer requires an operating system.
UNIX is a multi-user, multi-tasking operating system. Multiple users may have multiple tasks running
simultaneously. This is very different from PC operating systems such as MS-DOS or MS-Windows
(which allows multiple tasks to be carried out simultaneously but not multiple users).
UNIX is a machine independent operating system. Not specific to just one type of computer
hardware. Designed from the beginning to be independent of the computer hardware.
UNIX is a software development environment. Was born in and designed to function within this type
of environment.
The "UNIX" trademark, previously owned by AT&T and then deeded to UNIX Systems Laboratories
(USL), an AT&T subsidiary, passed to Novell when it acquired USL. After a brief period of
negotiations with rival Unix vendors, namely, Sun Microsystems, Santa Cruz Operation,
International Business Machines, and Hewlett-Packard, Novell granted exclusive licensing rights of
the UNIX trademark to X/Open Co. Ltd., an Open Systems industry standards branding agent based
in the United Kingdom.
. Why UNIX?
 Hardware independence
o operating system code is written in C language rather than a specific assembly language
o operating system software can be easily moved from one hardware system to another
o UNIX applications can be easily moved to other UNIX machines. Porting is usually as
simple as transfer of the source and a recompile
 Productive environment for software development
o rich set of tools
o versatile command language
 Distributed processing and multi-tasking
UNIX Components
 Kernel
o The core of the UNIX system. Loaded at system start up (boot). Memory-resident control
o Manages the entire resources of the system, presenting them to you and every other user
as a coherent system. Provides service to user applications such as device management,
process scheduling, etc.
o Example functions performed by the kernel are:
 managing the machine's memory and allocating it to each process.
 scheduling the work done by the CPU so that the work of each user is carried out as
efficiently as is possible.
 accomplishing the transfer of data from one part of the machine to another
 interpreting and executing instructions from the shell
 enforcing file access permissions
o You do not need to know anything about the kernel in order to use a UNIX system. These
details are provided for your information only.
 Shell
o Whenever you login to a Unix system you are placed in a shell program. The shell's prompt
is usually visible at the cursor's position on your screen. To get your work done, you enter
commands at this prompt.
The shell is a command interpreter; it takes each command and passes it to the operating
system kernel to be acted upon. It then displays the results of this operation on your screen.
o Several shells are usually available on any UNIX system, each with its own strengths and
o Different users may use different shells. Initially, your system adminstrator will supply a
default shell, which can be overridden or changed. The most commonly available shells are:
 Bourne shell (sh)
 C shell (csh)
 Korn shell (ksh)
 TC Shell (tcsh)
 Bourne Again Shell (bash)
o Each shell also includes its own programming language. Command files, called "shell
scripts" are used to accomplish a series of tasks.
o UNIX provides several hundred utility programs, often referred to as commands.
o Accomplish universal functions
 editing
 file maintenance
 printing
 sorting
 programming support
 online info
 etc.
o Modular: single functions can be grouped to perform more complex tasks
Introduction to Windows Operating System
Graphic User Interface based OS
DOS is a command-oriented operating system, i.e. we have to remember the commands and the
corresponding syntaxes to get our work done by DOS. Innumerable software packages and programs were
developed based on DOS. MSDOS remained very popular OS for many years till a more powerful method of
interacting with computer called WIMP was introduced , which supported Graphic User Interface, GUI, in
WIMP system uses windows, icons, menus and a pointer. Window is a part of the screen wherein the user
works on the program. Each program was shown as a small picture known as icon. The options available for
the user are displayed in the form of a menu. A more powerful input device (commonly mouse) is used as a
pointing device. So instead of typing the commands, it is now possible to point out to a picture and select the
menu options from a menu.
As pictures reveal more than texts, WIMP gained popularity over command-based DOS. Windows
operating system is entirely based on WIMP. The user need not remember the commands and its syntaxes
any more. Of course it is still possible for the old fashioned user to type in commands as Windows include
MSDOS. Every task that the OS can do is displayed as icons or menu items thus popularizing the use of
computers among many users. Thanks to the Windows and the software packages developed for working
with Windows, the awareness of use of computers by the layman has multiplied manifold. PCs are now not
only easily affordable but also usable by common people. Working with Windows is more fun and productive
than earlier.
Features of Windows
 Graphic User Interface
In DOS, users had to interact with the computer by typing in commands, where as, in Windows users
select the graphics to communicate. Windows is based on Graphic User Interface. GUI provides us a facility
to control the system through pictures symbols and icons on the screen by clicking and moving a pointing
device. This makes the user – computer interaction easier, faster and interesting. Problem of remembering
the syntax rules of the command , which was more error prone, is completely eliminated. Thus the speed of
execution is also improved.
 Multitasking
More than one application can run simultaneously in Windows, as it is a multitask system. One need
not close the previous program in order to start a next one like it is done in DOS. In fact we can open many
windows and navigate between them. For example, while working on Word document, if certain calculations
are to be done, we may open Calculator program and obtain the result and get back to our task in word. In
fact it is possible to copy the results of one program into another one. We can hear our favourite music on
computer while working on our program. This is made possible because Windows allows us to open many
program and other windows on the desktop screen, at the same time. Program opens just by a click of the
mouse. It is also possible to keep our favourite and frequently used programs, document, web site or folders
in task bar or in Start menu or in desktop so that we can access them quickly.
 Easy to use
Installing new hardware is no more a big job. Windows allows us to plug in a new hardware easily
and use it instantly. This plug and play feature of Windows is easy to use.
 Reliable
There are diagnostic tools and troubleshooter tools, which help in checking the hard disk and the system
files regularly and even fix some of the problems automatically. Windows can be kept up-to-date by
accessing a web site for finding solution to our Windows related problems. This makes Windows more
 Effective and faster
Maintenance wizard of Windows helps in improving the computer‟s speed and efficiency. Power
management feature of Windows minimizes the power usage whenever possible. For example, the monitor
can be made to go in a sleep-mode when not used for a specific time. File management of Windows is very
effective and faster.
 Integration with Web
Using internet through Windows is easier, faster and interesting. Windows internet connection
wizard makes connection to World Wide Web simple. Microsoft Front Page Express facilitates us to create
web pages easily. Web-style Active Desktop allows us to view web pages in any window. Microsoft Outlook
Express is a powerful software, which helps in net communication. We can send electronic mails (emails)
and post messages to newsgroups. We can save Internet connection expenses by saving a web page and
view it offline. Net conferencing is made simple by use of Microsoft Net meeting.
In addition to locating files on our personal computer, or a network computer, the enhanced Find feature of
Windows can locate content on Internet.
Windows supports high quality multimedia, which includes images, sound, music, and movies, thus
making the computer more entertaining and fun to work with and making it more productive. Windows
supports digital audio and video. With Microsoft WebTV for Windows one can even watch some TV
telecasts. We can receive live concerts and other exciting events. NetShow provides an easy way to receive
live multimedia. Video conferencing has been a major application, which is very useful, thanks to Windows.
If you are bored looking at the same mouse pointer symbols and are fed up seeing the same background
and wallpaper, Windows offers variety of desktop themes like wallpaper, screen savers, 3D icons, fonts,
colours and mouse pointer symbols to choose from.
 Help feature
Every program of Windows has a feature called online help. This means while working on a
program, if you have doubts, you need not refer to the book or manuals, Windows online Help menu is just
for this purpose. Clicking on Help menu opens help window; it offers content wise help, displays help on
topic, which are indexed; you can also type in a question and Windows help facility searches for the answer.
Even help window has Help menu to know more about how to use help.
Windows offers interactive online tutorial, which a new user may find helpful.
Minimum Hardware Requirement
8MB RAM , 260 MB Hard Disk , Mouse , EGA/VGA Monitor
Why This Requirement Are Used?
 This Special requirement are essential for Windows Operating System because windows
operating system required more space.
Windows Operating System is a multitasking operating system that means windows
operating system support multiple task . Multiple software program can execute
 VGA (Visual Graphics Adapter) or EGA (Enhancement Graphics Adapter) monitor is required
for windows operating system because this monitor provides high resolution. Resolution is
the unit through which can measure the sharpness of image. More number of dots or pixel
provides high resolution
Starting Windows
When you switch on the computer, which has Windows98 OS (many versions of Windows are
available), the opening screen will look similar to Figure below.
Task bar
Mouse pointer
This screen is called Desktop. This is the area where we will be doing all the works. Desktop has
many small pictures known as Icons. Number of icons on the desktop varies from computer to computer.
You can create icons called shortcuts for the programs , which you use frequently and place them on the
desktop. So your screen may look different from the figure shown here. At the bottom of the desktop a gray
bar like strip is displayed. This is called Task Bar. Start button is situated on the extreme left side of the task
bar. Task bar and Start button can be used for navigating through Windows98, as both are always available
on the desktop no matter how many windows you open. When you open many windows, some of them may
hide behind the other. You can see all the opened windows in minimized button form on the task bar. All the
tasks , which are currently being done, are displayed in task bar, hence, the name task bar. Start button is a
very important button as almost any task can be accomplished by a click of Start button. We can open any
document, program, find the location of file, customize the system, get windows help and do many more
Start button
Task bar
It is one of the most component of windows operating system. It is the initial screen appear on to the monitor
after after booting. This screen indicates now the machine is on or ready to execute any GUI based or
command based program .This screen used as a background screen it contain two components.
It is a small picture or graphics which associated with a program. When this picture or graphics select
through mouse the associated program executed through windows operating system.
It is a horizontal bar which appear at bottom edge of the
desktop. But it can move four edge at the desktop. (Left, Right,
Top, Bottom). Taskbar is used to switch between different
program or software. Taskbar consist of
1-Start Button
2-Volume Control
Press the mouse pointer at the taskbar and right click on it. It
will display a popup menu then choose the option properties. It
will display a dialog box with taskbar appearance.
Lock the taskbar
If the option will be checked then the taskbar position can not
be change.
Auto hide the taskbar
If the option will be checked the taskbar automatically hide.
When the mouse pointer point on the taskbar then the taskbar
will be show
Keep the taskbar on top of other windows
If the option will be checked then the taskbar display in other application.
Clock is one of the most important component of the taskbar. Through
which the system date or time can be changed. It will display the current
date and time when the mouse pointer placed on this icon. It provides a
calendar with clock in which user can adjust the date and time.
This component used for the multimedia application to increase or
decrease the volume .
When windows operating system is install some folder is created by
This folder contain the list of
all the storage device
It contain the document file which are created in windows operating system. By default windows operating
system try to save different file in this folder
This folder is known as protection layer which contain the deleted files. When user delete a file from any
folder or also folder the folder or file store in the recycle bin for restoring. From this folder the files and
folder can be restore again.
Select the file or folder which are deleted then right click on mouse then choose restore.
This folder is used to contain the program files or application files. The files which are store in this folder that
are appears onto the desktop inform of icon.
It is a rectangular frame having three control button.
1-Closed Button :
It is symbol like a (X) mark through which closed the current windows
2-Maximized or Restore Button :
Maximized button expand the windows over the desktop. Restore button
switched back to its last position or its size.
3-Minimized Button :
Minimized button minimized the windows and convert into a icon which are appear on the
Each an every application program open with its own rectangular frame or windows. Each an every windows
identify through frame. It is appear at the top of the windows.
It is the file manager of windows operating system. It is used as a tool to manage files and folders. It is
display the file ad folder structure in a graphical way. This windows divided into two part. The first part
display all the storage device name and main folder name. Right part of this windows list all the files and
sub-folder of the selected folder.
This bar is display the current open application name. It holds a control menu at the left edge of the title
bar. By using mouse or key board (Alt+ spacebar) we can open the control menu. It is provides different
command option like (Closed, Minimized, Maximized, Size, Move, Restore) etc. By using control menu we
can control the explorer windows. Title bar also holds three button at the right side . First button is called
minimized button, second one is called maximized or restore button and third one is called closed button.
The menu bar display the name of the menus. Menu bar activate by holding down Alt + Underscore
letter of the menu. Each menu gives there sub menu. To sub menu simply press the under score letter. By
using four navigating keys (
) we can move left, right, down, up.
Standard tool bar provides different command inform of icon like search, open, back, print etc.
This bar display the current position of the file directory.
Status bar display the information about various step.
* Create a files and folders
* Copy a files and folders
* Rename a files and folders
* Delete a files and folders
* Moves a files and folders
Open the specified folder then click on files menu from menu bar. It will display option where we can choose
new option. It will display different application name like paint, note pad, word pad, text document etc. We
can choose the required application. Then enter the file name and right click on it. Then choose open option
where we can write specified content .Go to file menu and click on save option . Then click on close button.
Open the specified folder then right click on windows area. Then select new option from it. Choose the
specified application and enter the name of the file. Right click on it and choose open option and type the
content. Right click on work area and choose save option. Then click on close button.
Choose the specified file & folder by using left click on mouse. Then choose copy option from edit menu.
Open the target folder then go to edit option and choose paste option.
Right click on the specified file & folder and choose copy from it. Open the target folder and right click on
it. Then choose paste option from it.
1st Way- Select the file & folder and go to file menu and choose rename option then enter the new name.
2nd Way- Select the file & folder and right click on it. Then choose rename option and enter the new name.
1st Way- First select the specified file & folder then select the edit menu then choose cut option. Open the
target folder and go to edit menu and choose paste option.
2nd Way- First select the file & folder then right click on it . Then choose cut option and select the target
folder. Right click on windows area and choose paste option.
1st Way- Select the file & folder then choose delete option from file menu or simply press delete key. It will
display a message to the user do you want to send the file or folder to recycle bin. If yes then selected file
and folder will be erase.
2nd Way- Select the file & folder and right click on it then choose delete option. It will display a message to
the user. If yes then selected files & folder will be erase.
Windows it self provide set of program in accessories like* Game
* Paint
* Notepad
* WordPad
* System Tools
* Character Map
* Entertainment
Windows accessories provides a drawing program that is known as paint brush. This program is provides
tool box and color box. Through which user can draw any colorful image or graphics. Windows operating
system use the extension name .bmp for this paint brush file.
It is windows editor in which user can simply type the information and store in it. It does not support different
formatting the
task and graphic. The extension name of notepad file is .txt .
It is just like windows editor but this option provides set of menu and tools which support graphic and
different font formatting. WordPad program provides a formatting tool bar for formatting of text. The
extension name of .doc can be used by default to the file name.
Windows operating system needs to manage and check various components like disk, monitor for that it is
provides a tool windows system tools.
In windows operating system maximum 256 character can be used to naming a files including blank space.
In between the files name it can support the character, number, symbol and blank space etc
Windows operating system provides the features of OLE. It is a method or process through which the
document, image, graphic can be inserted to the another document with linking to source one. It is create a
link between the source and destination.
FOR EXAMPLEA paint brush picture can be inserted to ms word with linking. For OLE used the paste option that is
paste special.
• Open the first application and select text, image, graphic which user want to embedded with link.
• Then choose edit copy.
• Open the another application or document where user wants to insert the object.
• Then choose edit-paste special . It will display a dialog box then click on the paste link button
In windows operating system tools through which files and folders can be search and gives the information
about its location and path. Click on the start button it will display a program list. Select search option then
choose files and folder option. It will display a dialog box where user can type the files and folders name
which use want to search. Then choose the storage devices or folder from where the search operation will
be start.
In windows operating system various operating control object are used through which control the operation
or program.
*Push Button
*Radio Button
*Check Box
*List Box
*Pull down Menu
*Popup Menu
Press the mouse pointer on to the desktop and right click on it . It will display option that is desktop
properties. Then choose the properties option from the desktop. It will display a dialog box that is properties
dialog box. This dialog box having the tabs like* Background
* Screensaver
* Appearance
* Settings
* themes
Here user can change the desktop or wallpaper. It will provides a list box of JPG or BMP files through which
user can change the wallpaper or background.
Right click on desktop
Choose background style
It is a program which can run automatically when the machine left without any operation this program will be
execute. User can set the time period for the screensaver program.
Right click on desktop
Select the screensaver style
Set the wait time
Through this option user can change the appearance of the desktop, icon, dialog box etc. Appearance
means it can change the foreground or background color.
Right click on desk top
Appearance ->
Choose color scheme
-> Choose the item -> Ok
Apply -> Ok
Right click on desktop
-> properties ->
decrease the resolution -> Apply -> Ok
Click on start button
-> Setting
Control panel -> Right click on mouse
and secondary buttons -> Apply -> OK
Left Mouse Button
Choose the font size
Settings ->
Set the color quality ->
Open ->
Buttons ->
Increase or
Click Switch primary
Right Mouse Button
Click on start button
Control panel
--> click on mouse ->
Apply 
Pointers ->
browse ->
Select pointer ->
Right click on start button  Setting  Control panel  Right click on Accessibility option
Mouse  check mark on use MouseKey option
 Apply 
Logging On
Open 
The following instructions are for logging onto any machine running Windows
XP in CMU's Clusters.
When you arrive at a machine, you should see a Welcome to Windows box
Hold down the Ctrl and Alt keys and press the Del key (often written
Ctrl+Alt+Delete); a Log on to Windows box will pop up.
In the User Name box, enter your Andrew username.
In the Password box, enter your Andrew password (it will appear as
Ensure the Log on to option box says ANDREW.CMU.EDU
(Kerberos Realm); if it is showing anything else, select this option
from this option box.
Click the button labelled OK or press the Enter/Return key.
If you enter your username and password correctly, you will be logged on;
otherwise repeat this process until you successfully logged on.
Logging Off
When you are finished working on a cluster machine, you should always log
off. Before logging off, make sure to Backup all your files that contain useful
information. Then ...
Drag and Drop all your folders/files from the desktop into the Recycle
Bin icon.
Drag and Drop all your folders/files from c:\temp into the Recycle Bin
Double Click the Recycle Bin icon.
Select File | Empty Recycle Bin.
Click Yes for Confirm multiple File Delete.
To actually log off
Click Start and select Shutdown....
The What do you want the computer to do text field should show
Log off username (where username is your username on Andrew); if
this action is not selected, select it.
Click OK or press Enter/Return.
At this point the machine will begin logging you off. To ensure that this
operation is successful, you should wait until the Welcome to Windows box
Viewing File
File extensions are the the part of the file name after the period (e.g., the mcp
in project.mcp or the java in It is often very useful to be
able to see both file names and extensions. On some Windows operating
systems (e.g., 2000), this is the default; on others (e.g., NT) you must follow
the instructions below.
Open an Explorer window.
Select View | Options...
Click the View tab, if it is not already visible.
Ensure the box labeled Hide file extensions for known types is NOT
checked (click it if it is checked to toggle it to unchecked).
Click OK
You should now be able to see the extensions of all files.
To rename a folder or file (if it is a file with an extension, the extension should
Folders and Files remain the same: you will be warned if you accidentally change it);
Right Click the folder or file.
In its context menu, click the Rename option.
Type the new name (and the same extension) in the highlighted blue
The folder or file should now have the name that you typed.
Java programs often input/output text in the console window. If scrolling is
enabled on these windows, you can look at all the text printed. On some
Scrolling in the
Console Window Windows operating systems (e.g., Windows 2000), this is the default (300
lines); on others (e.g., Windows NT) you must follow the instructions below.
To allow [more] scrolling in this window, so that you can see a [longer] history
of all your program's input/output, perform the following steps (you may have
to perform these steps each time that you log on):
Right Click in the header (on the top of the frame) of the Console
Click Properties.
Select the Layout tab.
In the Screen Buffer Size section, type 1000 (or an even bigger
number) into the Height text field.
Click OK.
On the Apply Properties window, check the bullet marked Save
properties for future windows with same title.
Click OK.
The console window should now be scrollable (you should see the scrolling tab
along the right border of the window)
Zipping Files
WinZip (the zipping/unzippng software) is already installed on all the
computers in the cluster. If you want to install it on your own computer, follow
this link to the WinZip web page to download a copy).
Programming assignments must be turned in as single zip file that contains all
the files inside a project folder. To zip all the files in a folder named F, for
example, into a single zip file
Right Click the folder that you want to zip.
In its context menu, select the Add to option (note that the name
of the folder, in this example F, always precedes the zip extension; do
not use the more generic Add to Zip operation).
A WinZip window will automatically appear and disappear from your screen
(this might happen so fast that you do not see it). When finished you should see
a new file on your desktop (or wherever the folder you zipped came from) with
the same names as your folder (the folder will still be there too) and the zip file
extension (so in this case, the zip file is named
Unzipping Files
To unzip all the files in a zip file, for example
Right Click the zip file that you want to unzip.
In its context menu, select the Extract to folder C:\...F option (note
that the name of the zip file, in this example F, always appears at the
end of the selection).
When finished you should see a new folder on your desktop (or wherever the
folder you unzipped came from) with the same names as the zip file (the zip
file will still be there too; so in this case, the folder is named F).
Difference Between Windows XP & Widows 7 & Windows 8
Key Difference: Windows 7 and Windows XP are two operating systems that are offered by
Microsoft for running on their PCs and Laptops. Windows 7 offers a new layout and look, while
Windows XP offered upgrades on the older Windows 2000 and Windows ME systems.
Windows 7 was the upgrade for the Windows XP OS and was launched in October 2009. Both of these
systems offered some great features for users. Usage for Windows XP has declined and is only found on
older computers, while Windows 7 has become the most used OS
The Windows 7 required a 1 GHz processor, 1 GB RAM, DirectX 9 graphics processor with WDDM driver
model 1.0, 16-20 GB (depending on architecture) free disk space and a DVD-ROM drive.
The Windows XP required a 233 MHz clock speed, 64 GB RAM, Super VGA (800 x 600) or higher
resolution, 1.5 GB or higher HDD space, CD-ROM drive, keyboard and mouse and sound card, speakers or
Windows 8 is the latest operating system by Microsoft
for its PCs, laptops and tablets. The newest OS hit the
markets in October 2012 and had a whole new look.
The company has launched the operating system
keeping in mind the constant upgrade from keyboard
and mouse PCs to touch tablets. Windows 8 was
launched with touch compatibility in mind. The system
sports a whole new Menu Screen, with a new ‘Live Tile’
format that is found in the Windows phones. These tiles
automatically update to show users new e-mails or
other information.
Windows 8 also supports new advancing technology such as USB 3.0, 4Kn Advanced Format, near field
communications, cloud computing, and the low-power ARM architecture. This is the first OS that allows ARM
architecture support, with the previous OS only supporting IA-32 and x86-64 architectures. It also offers
built-in antivirus capabilities and advanced security features. Other features that make this OS handier are
the Windows Store and app compatibility. The OS supports apps and are allow certain apps to dock on one
side of the screen, while other apps can open in to proper programs. The OS also allows users to purchase
and download apps from the Windows Store and use them on their laptops, PC as they would on their
Windows 8 is offered in four editions: Windows 8, Windows 8 Pro, Windows 8 Enterprise and Windows RT.
Windows 8 comes pre-loaded on the new PCs by the company. Windows 8 Pro is aimed at power users and
professionals. Windows 8 Enterprise is aimed at business environments and is available through volume
licensing, while Windows RT is the only edition comes preloaded on new ARM-based devices for Windows.
In order to run Windows 8, the user must have certain system requirements: 1 GHz clock rate, 1-2 GB RAM
(depending on the architecture), DirectX 9 graphics device WDDM 1.0 or higher driver, 1024×768 pixels
display, keyboard and mouse and 16-20 GB internal storage space.
Windows XP
Windows 7
Windows 8
Proprietary commercial
Proprietary commercial
Proprietary commercial
Worldwide release
October 25, 2001
October 22, 2009
October 26, 2012
Stable release
April 21, 2008
February 22, 2011
August 1, 2012
Kernel type
Platform support
IA-32, x86-64 and Itanium
IA-32 and x86-64
IA-32, x64, and ARM
Preceded by
Windows 2000
Windows ME
Windows Vista
Windows 7
Succeeded by
Windows Vista
Windows 8
Physical Memory Limits
4 GB-128 GB depending on
the version and the
2 – 192 GB depending on the
version and architecture.
4 GB -2048 GB depending
on architecture.
32 for 32-bit, 64 for 64-bit
32 for 32-bit, 256 for 64-bit
32 for 32-bit, 256 for 64-bit
New Features
GDI+ graphics
DirectX 8.1
upgradeable to
DirectX 9.0c
Improved Taskbar
New features
(task panes, tiles,
improved sorting
and grouping, builtin CD player,
Autoplay, Simple
File Sharing, etc.)
Faster start-up
Ability to discard a
newer device
driver in favor of
previous one.
More user-friendly
Fast user
ClearType Font
New networking
features (Windows
Firewall, Internet
Touch and
Support for virtual
hard disks
performance on
Faster startup
Support of ARM
new "Hybrid Boot"
New lock screen
New Start Menu
Improved boot
Native USB 3.0
4K Advanced
Microsoft Account
New version of
Windows Media
XPS Essential Pack
New calculator
Jump Lists
Show desktop
button shifted to
right-hand size
13 Additional
Sound Schemes
Window borders
and the taskbar do
Windows Store
Windows To Go
NFC support
Windows Explorer
renamed to File
File Explorer
includes a ribbon in
place of a
command bar.
Storage Spaces
allows combination
of different sized
hard disks
Sharing integration
with UPnP, NAT
traversal APIs,
Quality of Service
features, IPv6 and
Teredo tunneling,
Removed Features
New security
Improved media
speech recognition
and digital ink
CD Player, DVD
Player and Imaging
for Windows
NetBEUI and
NetDDE are
Allows more
A new version of
Microsoft Virtual PC,
newly renamed as
Windows Virtual PC
Supports the
mounting of a virtual
hard disk (VHD) as
normal data storage.
Assistance and
Remote Desktop
not turn opaque
when a window is
DLC and
AppleTalk network
protocols are
Service Pack 2
and Service Pack 3
also remove
features from
Windows XP.
Shadow Copy
Redesigned Task
Additional Security
Parental Controls,
integration with
online services
synchronization to
SkyDrive App.
Xbox branded
multi-media apps
Internet Explorer
10 as a program
and an app.’.
Improved backup
and restore
Classic Start Menu
user interface
Traditional Start
Few Taskbar
Windows Media
Player no longer
supports DVDs
Windows Explorer
Windows Media
Center as a
purchasable option
Changes in
Backup and
Shadow Copy
devices are not
The Remote
Desktop Protocol
supports real-time
Windows Media
Player features
Windows Photo
Gallery, Windows
Movie Maker,
Windows Calendar
and Windows Mail.
Windows Common Short Keyboard Command
Win+Space operates as a keyboard shortcut for Aero Peek.
Win+Up and Win+Down are new shortcuts for Maximize and Restore/Minimize.
Win+Shift+Up vertically maximises the current window
Win+Left and Win+Right snap the current window to the left or right half of the current display;
successive keypresses will move the window to other monitors in a multi-monitor configuration.
Win+Shift+Left and Win+Shift+Right move the current window to the left or right display.
Win+ + and Win+ - (minus sign) zoom the desktop in and out.
Win+Home operates as a keyboard shortcut for Aero Shake.
Win+P shows an "external display options" selector that gives the user the choice of showing the
desktop on only the computer's screen, only the external display, on both at the same time
(mirroring), or on both displays with independent desktops (extending).
Shift + Click, or Middle click starts a new instance of the application, regardless of whether it's
already running.
Ctrl + Shift + Click starts a new instance with Administrator privileges; by default, a User Account
Control prompt will be displayed.
Shift + Right-click shows the classic Window menu (Restore / Minimize / Move / etc); right-clicking
on the application's thumbnail image will also show this menu. If the icon being clicked on is a
grouped icon, the classic menu with Restore All / Minimize All / Close All menu is shown.
Ctrl + Click on a grouped icon cycles between the windows (or tabs) in the group.
MS WORD is word processing application software which is a part of office automation package. Office
automation means computerization of file and document of office is called office automation. This is also
known as electronic data processing (EDP). MS office is most user friendly application software it supports
GUI & OLE. MS office provides following tools & applications in its package.
1. Word processing
2. Database management
3. Spreadsheet application
4. Ms outlook
5. Ms publisher
6. Database management
What is word processing ?
Word processing by means of processing of text, sentence & document. MS word is a complete & full
featured word processing software. MS word provides various tools & application for word processing
application. Word processing by means of creating of letter, reports, memos etc.
What type of items are covered in Word Processing?
* Use and manipulation of the insertion point.
* Selecting text, insert and overtype.
* Document formatting: header and footer,
margins, page breaks
* Changing fonts, changing color and size of font.
* Use of spell check and thesaurus.
* Setting tabs.
* Cut, copy, and paste.
* Page setup (portrait/landscape).
HARD copy & SOFT copy
Document stored in memory device is known
as soft copy. In soft copy allows for
modification & changes. Soft copy uses the
bytes of memory. Hard copy is the document
printed on paper. Hard copy doesn’t allow for
modification & changes. Hard copy uses the
MS word is a most useful and popular software used in office for documentation work. In MS word user can
create letter, report, memo, proposals and other documentation operations. In MS word the files are created
known as document save with extension name .DOC
Features of MS WORD
(i)On-line help system
(ii) Auto correct
(iii) Spell checking
(iv) Grammatical checking
(v) Find document fast
vi) New templates
(vii) Highlight your main point
(Viii) Word-Wrap:- this feature allow us to type the words without bothering about the line. It automatically
change the line when it goes out of right margin.
(ix) Tooltip :- Ms word provide the tooltip text to identify the buttons or objects provided by MS word. Just
place the mouse pointer on the control button or object it display the tooltip.
MS WORD Windows consists of two windows.
APPLICATION WINDOWS It is the main windows of MS-WORD which contain the components. Like
Title bars displays the name of the document .When the new document create the title bar display as
Microsoft Word Document1. When the file save the Document1 will be replaced with a new name.
It is a rectangular frame having three control button. Like MINIMIZE BUTTON, MAXIMIZE BUTTON,
Menu bar displays the name of the menus. Activate the menu bar by holding down Alt+Underscored letter of
the menu. Each menu gives their submenus. To choose sub menu simply press the underscored letter. By
using Arrows keys Move up, Down, Left and Right between the menu and option.
The first section of the status bar display the current page number, section number, page number is followed
by count the page no and the total number of pages in the document. It display the line number and column
Tool bars are used for easy & quick operations.
STANDARD TOOLBAR Standard toolbar provides different buttons in form of icon. Like cut, copy, new,
open, paste, print, undo etc
FORMATTING TOOLBAR : Formatting toolbar provides the facility to format the character, paragraph. It will
make the character bold, under line or Italic. By using formatting toolbar change the font size, Of the word
sentence etc.
One of the various tool bar which can be made available on the screen. This particular one is used for
making drawing in the document.
Document windows provides the blank white area known as work area where user can work, type letter,
alpha bate, symbols, insert pictures etc.
In work area the mouse pointer appears like I-beam.
In MS WORD windows we will get two scroll buttons or
bars. At the right side scroll bar is called Vertical scroll
bar and at the bottom the status bar is called Horizontal
bar. The box within the scroll bar is called scroll box.
Vertical scroll is used to move lines up and down which
are not able to see in document at a time. In page layout
view two extra buttons appears at the button of vertical
scroll bar. The double headed up arrow moves to top of
provides page and double headed down arrows moves to
the bottom of next page. Horizontal scroll bar used to
move line left to right. Which are not able to see in
document at a time in normal view.
The ruler is found below the Ribbon.
you can use the ruler to change the format of your
document quickly. If your ruler is not visible, follow the
steps listed here:(1)Go to view menu (click)
(2) The click ruler in the show/hide group.
Toolbar provides various buttons for different task and
operation. It is used for easy and quick operation.
In MS-WORD user can work 2 ways.
(1)By using Mouse
(2)By using Keyboard
File menu
Creating A New Document
Choose File  New , It will ask for Blank Document or Template. Select Blank Document.
Before typing it is required to set the margin ,Page Size , Paper source etc. Choose File Page setup
You can change the page layout of the document. This option is used and set the page by means of Set
margin (top , button , left, right) ,Set paper size (A4, A3, Letter)
(1)Go to file menu--> page setup -->then click margins tab ->change the new margin setting from top , bottom ,left , right ,
gutter , gutter position The ok button (click)
(2) Each new document based on that automatically uses the
new margin setting.
Go to file menu page setup click then click the paper tab
select your paper size then ok button click.
Save As:- It is used to store your documents in your disk. To save a file you have to give a file name. The
file name can be up to 255 characters.
Step Write your document go to file menu Save As option (click) enter your file name save button (click).
It is used to rename the file or save the file with a name.
StepGo to file menu open option (click) select your file or document  open button (click). Go to file
menu Save As option (click)  enter your new name then press save button (click).
To open an existing document from the folder. It display a dialog box in which
1 select the folder where the document is stored then select the document
which wants to open.
File-Save To save the current changes & modification in the existing document
choose File-save.
It is used to save the document from webpage and save the document
extension name .HTML .
Before printing the document it is required to view how it is printed onto the
paper. Preview shows the document just like printed on paper.
File-Print This option is used to the document onto the paper. It
creates the hardcopy. It provides the print dialog box. In this dialog
box 1 select the printer by which the document is to be printed 
select the page to print  no of copies for the printing.
EDIT MENU: It provides various options for the purpose of editing of
the document that means modify, changing & delete text which are
type in the document.
For example:Cut, copy, paste, paste special, office clipboard ,undo, redo, find etc
UNDO (ctrl+Z)
Undo option is used to reverts/cancel the last action
Select your text, word, or sentence then press delete key. go to edit
menu click undo option.
REDO (Ctrl+Y)
Redo option is gives you the modified text/object back after using undo command. It repeats the last action.
Select your text, word or sentence then delete key press go to edit menu click  undo option click go to
edit menu click Redo option (Click)
PASTE (Ctrl+ V)
Paste the contents of the Clipboard on the document.
Step:Selected text or object go to edit menu
Copy or cut option click  then pasting text in your target point (click) then paste option (click)
Office Clipboard works with the standard Copy and Paste commands. Just copy an item to the Office
Clipboard to add it to your collection, then paste it from the Office Clipboard into any Office document at any
time. The collected items stay on the Office Clipboard until you exit Office. The Office Clipboard can hold up
to 24 items. If you copy a 25th item, the first item in the Office Clipboard is deleted.
Go to edit menu  office clipboard option click  then select your text, sentence or word and copy or cut
option click (at least 24 items copy or cut) office clipboard task pane select your item then click  or
paste all option click then all item paste  and clear all option click (the clear the all items from office
PASTE SPECIAL: This option is used for the OLE operation. It paste the object with linking.
1 open two documents then Select your text, sentence or word from the 1 document go to Edit menu
copy or cut option click select the 2 document go to paste special  select the paste link option
select Microsoft Word Document object click  display as icon click  Change icon click select your
icon and ok button click--> ok button click.
FIND & REPLACE: Ms Word provides find & replace tool by which user can search the text in entire
document & also it allows to replace with the specified text.
Edit - Find
It provides the find dialog box & click on more button following options
will be available.
Match case: By default it searches the text ignores the case but if
match case is on it searches the text with case sensitive.
Match whole word only: By default it searches the text as a latter
wise. If this check box is on it searches as a word wise.
Wild card character: It supports the wild card character * & ? . *
represents set of characters & ? represents single character only.
Find sound like:
STEP Go to edit menu--> Replace click  find what:-enter your text (suppose apple ) replace with:- enter
your text (suppose orange)  then replace button click or replace all button click .
Go to
Go to edit menu  Go to option click  select your go to what then page, section or line click enter your
page, section or line number then next button click.
Select all: It is used to select the entire document.
Microsoft Word has different ways for you to get a good view of your work in the document, depending on
the task at hand.
(2)Web layout
(3)Print layout
(4)Out line
Work in normal view for typing, editing, and formatting text. Normal view shows text formatting but simplifies
the layout of the page so that you can type and edit quickly. In normal view, page boundaries, headers and
footers, backgrounds, drawing objects, and pictures that do not have the In line with text wrapping style do
not appear. To switch to normal view, click Normal on the View menu.
Layout View
Work in Web layout view when you are creating a Web page or a document that is viewed on the screen. In
Web layout view, you can see backgrounds, text is wrapped to fit the window, and graphics are positioned
just as they are in a Web browser. To switch to Web layout view, click Web Layout on the View menu.
Print Layout
Work in print layout view to see how text, graphics, and other elements will be positioned on the printed
page. This view is useful for editing headers and footers, for adjusting margins, and for working with columns
and drawing objects. If you'd like to type and edit text in this view, you can save screen space by hiding
white space at the top and bottom of the page. To switch to print layout view, click Print Layout on the View
Work in outline view to look at the structure of a document and to move, copy, and reorganize text by
dragging headings. In outline view, you can collapse a document to see only the main headings, or you can
expand it to see all headings and even body text. Outline view also makes it easy to work with master
documents. A master document makes it easier to organize and maintain a long document, such as a
multipart report or a book with chapters. In outline view, page boundaries, headers and footers, graphics,
and backgrounds do not appear. To switch to outline view, click Outline on the View menu.
The Document Map is a separate pane that displays a list of headings in the document. Use the Document
Map to quickly navigate through the document and keep track of your location in it.
Header always print at the top of the page within the top margin and footer always print end of the page
within the bottom margin. Through header &footer toolbar user can set the Text , Page No, date & time , No
of pages etc.
Go to view menu header and footer option click  insert your page no or date & time for header and
footer toolbar then close button click.
To display as much of your document as possible on the screen, you can switch to full-screen mode. In this
mode, Word removes distracting screen elements, such as toolbars and scroll bars.
Write your data  go to view menu  full screen option click Then display your full s
View-Toolbar: MS word provides various toolbar for easy & quick operations. We can ON & OFF the toolbar
from the application window.
Click on view menutoolbarsselect drawing toolbar it provides the button to draw following objects
Drawing tool bar provides buttons to draw the Autoshape ,Line , Rectangle , Circle , WordArt objects. It also
provides the tools for change the line color , text color, back color , Shadow , 3-D effects etc.
Same like use Word Art Toolbar , Picture Toolbar , Table & Border Tool bar.
View-Ruler: The ruler indicates the scale of the document for margin. It provides two rulers
horizontal ruler & vertical ruler. Horizontal ruler indicate the left & right margin & the vertical ruler
indicates the top & bottom margin.
View-Taskpane: Taskpan provides the list of basic task/operations which can performed in msword. Like Opening a document, New Document , Search a text etc.
View –Thumbnail : A miniature representation of a document pages . At the left side of the
document window it shows the thumbnail.
PAGE BREAK : It insert the page break line at the current position of the document that is known as manual
page break.
Go to insert menu  break option click  page break option click  Next page click
Go to insert menu page number option click select your
position and alignment  then format button click  choose
your number format  then ok button click  ok button
clickfull screen .
Auto Correct ,Autotext
DATE & TIME:-It inserts the current system date & time.
Go to insert menu --> date & time option click --> select your
available format --> then ok button click
Auto text provides a quick and easy way to store and insert
frequently used text.
Step:-Go to insert menu  Auto text option click  Auto text
click  enter your auto text  then add button click  show tool bar click or insert button click then ok
button click
INSERT YOUR TEXT :- Go to insert menu  Auto text option click  search your text then click .
Go to insert menu  Auto text option click  Auto text click  select your text  then insert button click.
SYMBOLS :- Go to insert menu  Symbols option click  Symbols tab click  Select your font  Select
your Symbol  then insert button click.
Go to insert menu  Comments option click  open
comment toolbar  write your comment  and new
comment click and delete comment click.
PICTURE:-Go to insert menu Picture option click  Clip
Art click enter your search text  search button click
then select your picture  then click.
OR:-Go to insert menu  picture option click  Clip Art
option click  Clip Organizer click Office collection click 
Select your collection list  right click on the picture  copy
option click  yes button click  right click on the document
 paste option click.
FORM FILE :- Go to insert menu  Picture option click 
From file option click  Select your picture  then insert
button click.
WORD ART:-Go to insert menu  Word Art option Click 
Select a style from the Word Art Gallery  then ok button click
 Choose a font and point size from the Font and size Drop
drown list  then ok button click.
Go to insert menu  object click  Select your object type 
then ok button click.
Go to insert menu  object click  Select your object type  Display as icon click  Select your icon or
browse button click  select your icon and ok button click  ok button click.
It is the identification mark of the document. Different bookmark can be used for different topics,
Step:-Select your text  then go to insert menu  bookmark option click enter your bookmark name 
Cheek it :-Go to edit menu  GO TO option click  Then Book mark click  Enter your book mark name or
select your Bookmark name then Go to button click.
Cross-Reference is the References of the Bookmarks in the document.
Select your text  then Go to insert menu  Book mark option click  enter your Book.Mark name  and
Add button Click  go to insert menu  Cross- reference option click  Select your reference type 
Bookmark click  Select your Book mark name  Then Insert button click.
Select your text  then Go to insert menu  Hyperlink option click  click the recent document or current
document  Select files  then ok button click.
•Format by means of change the appearance & look of the text, paragraph, Page and document.
•It provides various options like
•Format- Font
•Format – Paragraph
•Format – Border & Shading
•Format – Bullet & Numbering etc.
FONT:You can change the type of font you are using for text on
specific slides, or you can apply different fonts throughout a
whole presentation.
Steps:Select your text, sentence  Go to format menu  Font
option click  Change your font , font style, size, color,
effects or text effects  then ok button click.
•Alignment- The Selected paragraph can aligned either left ,
right, centered or Justified.
•Indention – Space & Gap used with margin Left & Right.
•Special – It provides two options i.e.
a) First line Indent- The 1st line change the position
towards right and other lines remains fixed.
b) Hanging Indent – The 1st Line remains fixed and others lines
shifted towards right. It appears like hangs the 1st line of
Spacing –Select your spacing paragraph before & after.
Writer your text with formatting then writer new text without
Formatting  Select your text with formatting  Then go to
Standard toolbar  Format painter option click  Drag on the Text without Formatting
Microsoft Word can automatically create bulleted and numbered lists as you type, or you can quickly add
bullets or numbers to existing lines of text.
Go to format menu Bullets & Numbering option click number click  choose your number style  then
customize button click  change your font style  choose your number style  ok button click  ok button
click .
HOW TO CREATE A BULLET STYLE:Go to format menu  Bullet & Numbering option click  Bullet click  Select your bullet style Customize
click click Character or picture button  choose your character style or picture style  font click  then
change your font style, font size, font color  then ok  ok button click  then ok button click.
Go to Format menu columns option click  enter your number of columns  then ok button click.
Go to format menu  columns option click  enter your number of columns=1  then ok button click.
DROP CAP:- Select your text  Suppose Select Text (Apple) then Drop cap option click  Select your
position  then ok button click.
TEXT DIRECTION:-Select your text  Suppose Select Text (Apple) then
Drop cap option click  Select your position  then ok button click  Go to
Format menu  Text Direction Option Click  Select your orientation 
then ok button click.
CHANGE CASE:- Select your Text  Go to format menu  Change option
click  Select your case  then ok button click.
BACKGROUND:-Go to format menu  Background option click  Choose
your more color or fill effect color  then ok button click.
Background option click  Printed watermark option click  Picture
Watermark option click  Select picture button click  Select your picture
 then insert button click  Choose your scale size  Apply button click 
ok button click.
PRINTED WATERMARK FOR TEXT:- format menu  Background option
click  Printed watermark option click  Text watermark option click --> enter your text --> choose font
,size, color and layout --> ok button click.
STYLE & FORMATTING:Go to Format menu  Style & formatting option Click New
Style option click  Enter your name  Select Your Format
option  then Font option click  choose your font then ok 
change your paragraph, tab, boarder, frame , language and
numbering then ok buttons click  Shortcut key option click 
enter your shortcut key  Assign button click  then Ok.
By default, Microsoft Word checks spelling and grammar
automatically as you type, using wavy red underlines to indicate
possible spelling problems and wavy green underlines to indicate possible grammatical problems.
Step:- Write your text  then go tools menu  Spelling & Grammar option click  select your correct word
 then change button click.
Step:- Write your text  then go tools menu  Spelling & Grammar option click  select your correct word
 then change button click.
Set Language:-Go to tools menu  Language option click Set Language option click  Choose your
language  then ok button click
Thesaurus:- The thesaurus provides a list of synonyms for the text you look up, and highlights the one that
is closest to what you have typed. Any instances of seemingly inappropriate terms are coincidental.
Step:-Select your Text  then go to Tools menu  Language option click  Thesaurus option click 
Select your Synonym words  then Replace button click.
WORD COUNT:- Write your text  go to tools menu  Word count option click
AUTO SUMMARIZE Write your text  then go to tools menu  Auto Summarize option click  Select
your type of summary  then OK button click .
TRACK CHANGES:-Write Your document then save  Go to Tools menu click  Track changes option
click  Show the Reviewing tools bar  Close the Reviewing toolbar  go to file menu  then save option
Remove the Track Changes:- Go to file menu  open
option click  open the Track changes file  go to view
menu  Toolbars option click  Reviewing Toolbar
option click  Reject change / Delete comment option
Track change option click go to file menu  save
option click.
your data & save the document  go to Tools menu
Protect Document option click  Tracked changes
click  enter your password  then ok button click 
enter your reenter password  then ok button click  ok
Unprotect Document:- Go to Tools menu  Unprotect
Document option click  Enter password  Go to Tools
menu  Track Change option click Reject change /
Delete comment option click CTRL+S key press.
Protect Document for Comments & Forms:Type your data & save the document  go to Tools menu Protect Document option click click the
comments or Forms option  Enter your password OK button click  enter your reenter password then
OK button click  ok button click  go to file menu  save option click
Unprotect Document:- Go to Tools menu  Unprotect Document option click  enter your password 
then ok button click.
What is Mail Merge ?
The Mail Merge feature has been described here. In Ms-Word Mail Merge option is an important and every
way for office set up. Many times we required sending the same content of a letter to different individuals. By
using Mail Merge you can send the same letter to a number of persons without typing the content of the
letter again and again.
At the end of the lesson you should be able to:
understand the concept of Mail Merge
create a main document
create a data source
link the main document with the data source
merge print a document
In any working environment, there are situations when a similar type of letter or document is to be sent to
many persons who reside at different locations. The letters may contain the address of each recipient, in
addition to the standard information contained in the letter. One way of doing this is to print the letters by
changing the address each time in the document after printing such letter. But this would mean lot of effort
and time and also results in bad organisation.
Such problems are taken care of by the Mail Merge facility. In word processing, Mail Merge is the process of
transferring selected information from one document to another document.
Mail Merge is the facility which requires the following three information
General body of the letter called main document
Header Row, the record structure or the name of the fields, which will identify the data
Data for all the individuals, for whom the letters are to be generated also called data source
Mail Merge option of Word reads this data and physically merges it with Main document to generate letters
for all the persons or for all records in the data file.
(a) Main Document
In Mail Merge, Main Document is the common letter, which contains the common information for each of the
merged document. It also contains the field names, which contain the instructions for carrying out the merge.
(b) Data Source
Data Source is also called the Data File. It stores information to be brought into the Main document. The
data file table contains a column for each category of information, or data field, in the data file. The Header
Row is the first row of the table. It contains field names, which indicate the type of information in each
column. For example list of names and addresses.
Each field name must be unique and must begin with an alphabet/letter.
(c) Form Letter
Form letter is the resultant document of the mail merge operations, which contains the copy of the main
document along with each piece of information stored in the data file.
Steps Writer your letter--> Go to Tools menu --> Letters & Mailings option click --> Mail Merge Wizard option click
--> Select your document type --> letters click--> Next: Starting document click--> Use the current document
click--> Next: Select Recipients click--> Type a new list click --> Create option click -->Enter your new
Address List --> Or customize click --> Delete Field name or rename --> Add the New Field name --> then
Add button click --> enter your New address list --> close button click --> enter your file name --> save button
click --> Check your address list --> then ok button click -->Next: Write your letter option click --> Select your
letter style (Address block , Greetings line, Electronic, Postage, More items)--> More Items option click -->Insert merge field close button click --> next: Preview
your letters option click --> Next: Complete the merge option click --> Edit individual letters option click -->
All option click --> Ok button click.
MACRO:Macro is a tool which records the events occurred in ms-word. The recorded events can be played in future
to save the time.
A macro (macro: An action or a set of actions you can use to automate tasks. Macros are recorded in the
Visual Basic for Applications programming language.) in the Visual Basic Editor (Visual Basic Editor: An
environment in which you write new and edit existing Visual Basic for Applications code and procedures.
The Visual Basic Editor contains a complete debugging toolset for finding syntax, run-time, and logic
problems in your code.)
Go Tools menu  Macro option click  Record new macro option click  enter your macro name  ok
button click  Enter your data from document  then Stop recording click  Select your data then delete
 Go to tools menu  Macro option click  Macros option click  Select your macro name  run button
Create a New Macro with Keyboard:- Go Tools menu --> Macro option click --> Record new macro option
click --> Keyboard click --> Press new Shortcut key click --> enter your Shortcut key (CTRL+Y) --> Assign
button click --> Enter your data from document --> Stop Recording option click --> Select your data and
Delete --> Enter your Shortcut Key (CTRL+Y)
Remove Macro:-Go to Tools menu --> Macro option click --> Macros click --> Select your Macro name -->
Delete button click
AUTO CORRECT:- Go to Tools menu --> Auto correct option click--> Suppose Replace –(B) --> and With –
(BRAJRAJNAGAR) --> add button click --> Ok button click --> press on the word (B) & space key press -->
then automatic Write (BRAJRAJNAGAR)
How to Create a Table
1ST WAY:-Go to Table menu --> Draw Table option click --> Draw your table
2nd WAY:-Go to Table menu --> Insert option click --> Table option click --> Enter your No of Rows & No of
Columns --> then Ok button click
How to Insert the Row & Column:- Click the target row and column cell--> Go to Table menu --> Insert
option click --> then Choose the option Insert column left, right or Insert Row Above ,Below --> then click
How to Insert the Cells:- Click the Target Cell--> then go to Table menu click --> Insert Option Click -->
Cells option click --> Choose your Insert Cells option --> then ok button click
How to Delete the Table, Rows & Columns:-Click the target row and column cell--> Go to Table menu -->
Delete option click --> then Choose the option Table, Rows & Columns --> then clickHow to Delete the
Cells:-Click the Target cell --> then Go to Table menu -->Delete option click --> Choose your Delete cells
MERGE CELLS:-Select your cells--> then go to Table menu--> merge cells option click
SPLIT CELLS:-Click the target Cell --> then go to Table menu --> Split option click --> enter your No of rows
& No of columns --> then ok button click
SPLIT TABLE:- Click the target Cell --> then go to table menu --> Split table option click
TABLE AUTOFORMAT:-Select your Table --> Go to Table menu --> Table AutoFormat option click -->
Choose your table Style or new button click--> enter your format name --> Format button click--> Choose
your format option and change the Table format --> Apply button click--> then ok button click
AUTOFIT:- Click the target cell --> Then go to Table menu--> Auto fit Option click --> select your auto fit
option -->then click option --> ok button click.
CONVERT:-Select the table--> Go to Table menu --> Convert option click --> Table to text option click ->Select your Separate text with option click--> ok button click.
SORT:-Select your Table -->Go to table menu --> Sort option click --> Click Sort by option --> Select your
columns & Sort by Ascending or Descending option click --> then ok button click.
FORMULA:- Click the Target cell --> then Go to Table menu --> Formula option click--> Select your paste
function Formula then click --> enter your formula --> then ok button click
Table Properties:-Select your table --> then go to Table menu --> Table Properties click -->Select your table
alignment and setting boarder & setting --> & Select your Vertical Alignment --> then ok button click.
Window Menu
New Window:- Go to window menu --> New Window option click
Arrange All :- Go to Window menu --> new window option click --> go to Window menu click --> Arrange All
option click
Split Window :-Go to Window menu --> Split option click
Remove Split:- Go to window menu --> split option click --> go to Window menu --> Remove split option click
Assignment of Ms – Word
1. What do you mean by Word processing?
2. What do you mean by OLE ?
3. What do you mean by Editing ?
4. Explain about the Documentation .
5. What do you mean by Mail Merge. ?
6. Explain about the Paragraph formatting.
7. What is Page Layout ?
8. What is Custom Dictionary ?
9. What is Indent & Margin in Document ?
10. What do you mean by Orientation ?
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