computer fundamental bba/bca/bba(FT)/B.com(CA)

1. 1
Acknowledgement
Anything new started is always with mixed feelings. There is the joy of
novelty, the determination of a missionary, but also the apprehension of a
new comer. Will it click? Will it be liked? Will it serve any purpose at all? Is
it worth the effort?
From the responses received, I can safely say that the phase of
apprehension is over. Colleagues and friends from all over, esteemed
teachers and researchers have called up or written to encourage the
effort. I am extremely grateful to them. My esteemed guide and support of
Mr. Narendra Narang (Bamanendra) from Indore, Chairman-Vishisht
Education Society was the first to call and offer appreciation.
Dr.S.M. Anas Iqbal, Academic Director Institute (VSOM) to so many of
us, revered in the field of I.T., called me up to congratulate me and
providing valuable suggestions. I indeed felt blessed. a well respected
name in the field of Commerce HOD Prof. Shweta Arora and my grateful
thanks to him.
We wish to thank all of them for being with us. Co-operation of
colleagues, Prof. Ashish Mehta , Prof. Robin Neema , Prof. Shekhar
updhyay, Prof. Paridhi Mangal Jain , Prof. Dr. Narendra Singh , Prof.
Neha Mahiwal , Prof. Tripda Rawal , Prof. Vineet , Prof. Sandeep Kour
, Prof. Samuel Norment, Prof. Hemant Chaturvedi Prof. Vineeta, and
Prof. Anuja is on record of my acknowledgement and appreciated the
effort. My friend Mr. Akshay Johari has taken over typesetting and
printing work for which I wish to thank him wholeheartedly. Also co-
operation of Bharti Sunhere , Librarian Head is on record of my
acknowledgement.
I admire the patience with which he and his office carry out the numerous
corrections and additions in getting the monographs ready for printing.
My Father Shree Murlidharji Bhangdia from Indore writes back to say,
"It is an important issue and very timely and can be a good stimulus for
Indian authors to start addressing such problems in greater numbers...
Keep up the good work".
I seek your suggestions and advice, your views and opinions on the
issues raised by this collection. Please feel free to write or call. It will be a
great pleasure to interact with you.
Meanwhile, all the best.
Sanjay Maheshwsari

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Index
The History Of Computers 1
The Invention Of Computers 9
What Is A Computer 12
Classification Of Computers ! 13
Classification Of Computers ! 14
CPU Components 15
Input Unit: 16
Output Unit: 17
Central Processing Unit: 18
Input/Output Devices 18
Computers Generation 23
Advantage And Disadvantages 29
System Software And Application Software 30
Functions Of An Operating System: 31
Hardware 33
Software 36
Programmers 37
Disk Operating System (DOS) 40
Linux 45
Computer Viruses 46
Hardware Vs. Software 47
Networking Hardware Components 51
Computer Peripherals 52
Computer Parts List 53
Graphics Card 56
Sound Card 57
Sound Card 61
Physical Memory 62
Primary And Secondary Memory 63
Main Types Of RAM Memory 66
Hard Disk 68
RAM Vs. ROM 69
Algorithm 70
Flow Chart 74
Programming Languages 77
Electronic Communication 78
Directory And Files 81
PC Configuration 81
General Packet Radio Service 85
Search Engine Optimization 88
Demorgan’s Theorems 89
Number System 91
Boolean Algebra 96
SYSTEM SOFTWARE & APPLICATION SOFTWRE 99
Compiler 103
Compiler 104
Assemblers 105
Computer Language 105
Windows 107
Operating System 108

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Functions Of An Operating System 110
File System 111
Icon 114
Taskbar 116
Moving And Sizing The Taskbar 119
My Computer 121
Control Panel 123
Desktop 124
Files And Folders 131
Creating And Deleting Files 134
Back Up 136
The Disk Defragmenter 137
Screensaver 138
Passwords 138
Recycle Bin 139
Paint Brush 141
Ms-Word 141
Ms-Excel 142
Ms-Access 144
Tally 147
Video Conferencing 149
DECISION SUPPORT SYSTEM 153
Expert System 154
Artificial Intelligence 155
Impact Of IT 157
Image Processing 160
Digital Image Processing 161
Virtual Reality 162
Information Superhighway 163
Online Shopping 164
E-Mail 165
4 GL 166
Internet Explorer 167
Network 169
Computer Keyword 170

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The History of Computers
Computers have wedged themselves into every facet of our lives—they are what
we would use as the symbolic representation of the modern world. But did you
know that the history of computers dates back to the 1800s?Indeed, the history
and evolution of computers is quite extraordinary—and with many early
computing technology innovations tied to defense contracts, much of this
information were kept secret from the public for decades. In this article, we
explore the development and progression of computers.
Mid-1800s-1930s: Early Mechanical Computers
The first computers were designed by Charles Babbage in the mid-1800s, and are
sometimes collectively known as the Babbage Engines. These include the
Difference Engine No. 1, the Analytical Engine, and the Difference Engine No. 2.
The Difference Engine was constructed from designs by Charles Babbage. Photo
by Allan J. Cronin These early computers were never completed during
Babbage’s lifetime, but their complete designs were preserved. Eventually, one
was built in 2002.
While these early mechanical computers bore little resemblance to the computers
in use today, they paved the way for a number of technologies that are used by
modern computers, or were instrumental in their development. These concepts
include of the idea of separating storage from processing, the logical structure of
computers, and the way that data and instructions are inputted and outputted.

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Z1 was used to take the U.S. Census in 1890.
Other important mechanical computers are the Automatic Electrical Tabulating
Machine—which was used in the U.S. Census of 1890 to handle data from more
than 62 million Americans—and the first binary computer: Konrad Zuse’s Z1,
which was developed in 1938 and was the precursor to the first electro-
mechanical computer.
1930s: Electro-Mechanical Computers
Electro-mechanical computers generally worked with relays and/or vacuum
tubes, which could be used as switches. Some electro-mechanical computers—
such as the Differential Analyzer built in 1930—used purely mechanical internals
but employed electric motors to power them. These early electro-mechanical
computers were either analog or were digital—such as the Model K and the
Complex Number Calculator, both produced by George Stibitz.Stibitz, by the
way, was also responsible for the first remote access computing, done at a
conference at Dartmouth College in New Hampshire. He took a teleprinter to the
conference, leaving his computer in New York City, and then proceeded to take
problems posed by the audience. He then entered the problems on the keypad of
his teleprompter, which outputted the answers afterward.
Z3 used floating-point numbers which improved the accuracy of calculations. It
was during the development of these early electro-mechanical computers that
many of the technologies and concepts still used today were first developed. The
Z3, a descendent of the Z1 developed by Konrad Zuse, was one such pioneering

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computer. The Z3 used floating-point numbers in computations and was the first
program-controlled digital computer.
Other electro-mechanical computers included Bombes, which were used during
WWII to decrypt German codes.
1940s: Electronic Computers
Colossus—whose name was fitting for its size—was developed during World
War II.The first electronic computers were developed during the World War II,
with the earliest of those being the Colossus. The Colossus was developed to
decrypt secret German codes during the war. It used vacuum tubes and paper tape
and could perform a number of Boolean (e.g. true/false, yes/no) logical
operations.
Williams Tube used RAM for its computations.
Another notable early electronic computer was nicknamed "The Baby" (officially
known as the Manchester Small-Scale Experimental Machine). While the
computer itself wasn’t remarkable—it was the first computer to use the Williams
Tube, a type of random access memory (RAM) that used a cathode-ray tube.
Some early electronic computers used decimal numeric systems (such as the
ENIAC and the Harvard Mark 1), while others—like the Atanasoff-Berry
Computer and the Colossus Mark 2—used binary systems. With the exception of

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the Atanasoff-Berry Computer, all the major models were programmable, either
using punch cards, patch cables and switches, or through stored programs in
memory.
1950s: The First Commercial Computers
The first commercially available computers came in the 1950s. While computing
up until this time had mainly focused on scientific, mathematical, and defense
capabilities, new computers were designed for business functions, such as
banking and accounting.
The J. Lyons Company, which was a British catering firm, invested heavily in
some of these early computers. In 1951, LEO (Lyons Electronic Office) became
the first computer to run a regular routine office job. By November of that year,
they were using the LEO to run a weekly bakery valuations job.
The UNIVAC was the first mass-produced computer. The UNIVAC was the first
commercial computer developed in the U.S., with its first unit delivered to the
U.S. Census Bureau. It was the first mass-produced computer, with more than
45 units eventually produced and sold.
The IBM 701 was another notable development in early commercial computing;
it was the first mainframe computer produced by IBM. It was around the same
time that the Fortran programming language was being developed (for the
704).

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The IBM 650 would cost you $4 million dollars if you bought it today.
A smaller IBM 650 was developed in the mid-1950s, and was popular due to its
smaller size and footprint (it still weighed over 900kg, with a separate 1350kg
power supply).They cost the equivalent of almost $4 million today (adjusted for
inflation).
Mid-1950s: Transistor Computers
The development of transistors led to the replacement of vacuum tubes, and
resulted in significantly smaller computers. In the beginning, they were less
reliable than the vacuum tubes they replaced, but they also consumed
significantly less power.
IBM 350 RAMAC used disk drives. These transistors also led to developments
in computer peripherals. The first disk drive, the IBM 350 RAMAC, was the
first of these introduced in 1956. Remote terminals also became more common
with these second-generation computers.
1960s: The Microchip and the Microprocessor
The microchip (or integrated circuit) is one of the most important advances in
computing technology. Many overlaps in history existed between microchip-
based computers and transistor-based computers throughout the 1960s, and even
into the early 1970s.

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Microchips allowed the manufacturing of smaller computers. Photo by Ioan
Sameli The microchip spurred the production of minicomputers and
microcomputers, which were small and inexpensive enough for small businesses
and even individuals to own. The microchip also led to the microprocessor,
another breakthrough technology that was important in the development of the
personal computer.
There were three microprocessor designs that came out at about the same time.
The first was produced by Intel (the 4004).
The first processors were 4-bit, but 8-bit models quickly followed by 1972. 16-bit
models were produced in 1973, and 32-bit models soon followed. AT&T Bell
Labs created the first fully 32-bit single-chip microprocessor, which used 32-bit
buses, 32-bit data paths, and 32-bit addresses, in 1980.The first 64-bit
microprocessors, were in use in the early 1990s in some markets, though they
didn’t appear in the PC market until the early 2000s.
1970s: Personal Computers
The first personal computers were built in the early 1970s. Most of these were
limited-production runs, and worked based on small-scale integrated circuits and
multi-chip CPUs.
The Commodore PET was a personal computer in the 70s. The Altair 8800 was
the first popular computer using a single-chip microprocessor. It was also sold in
kit form to electronics hobbyists, meaning purchasers had to assemble their own
computers.
Clones of this machine quickly cropped up, and soon there was an entire market
based on the design and architecture of the 8800. It also spawned a club based
around hobbyist computer builders, the Homebrew Computer Club.
1977 saw the rise of the "Trinity" (based on a reference in Byte magazine): the
Commodore PET, the Apple II, and the Tandy Corporation’s TRS-80. These
three computer models eventually went on to sell millions.

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These early PCs had between 4kB and 48kB of RAM. The Apple II was the only
one with a full-color, graphics-capable display, and eventually became the best-
seller among the trinity, with more than 4 million units sold.
1980s-1990s: The Early Notebooks and Laptops
One particularly notable development in the 1980s was the advent of the
commercially available portable computer.
Osborne 1 was small and portable enough to transport.
The first of these was the Osborne 1, in 1981. It had a tiny 5" monitor and was
large and heavy compared to modern laptops (weighing in at 23.5 pounds).
Portable computers continued to develop, though, and eventually became
streamlined and easily portable, as the notebooks we have today are. These early
portable computers were portable only in the most technical sense of the word.
Generally, they were anywhere from the size of a large electric typewriter to the
size of a suitcase.
The Gavilan SC was the first PC to be sold as a "laptop". The first laptop with a
flip form factor, was produced in 1982, but the first portable computer that was
actually marketed as a "laptop" was the Gavilan SC in 1983.
Early models had monochrome displays, though there were color displays
available starting in 1984 (the Commodore SX-64).Laptops grew in popularity as
they became smaller and lighter. By 1988, displays had reached VGA resolution,
and by 1993 they had 256-color screens. From there, resolutions and colors

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progressed quickly. Other hardware features added during the 1990s and early
2000s included high-capacity hard drives and optical drives.
Laptops typically come in three categories, as shown by these Mac books.
Laptops are generally broken down into a three different categories:
• Desktop replacements
• Standard notebooks
• Subnotebooks
Desktop replacements are usually larger, with displays of 15-17" and
performance comparable with some better desktop computers.
Standard notebooks usually have displays of 13-15" and are a good compromise
between performance and portability. Subnotebooks, including net books, have
displays smaller than 13" and fewer features than standard notebooks.
2000s: The Rise of Mobile Computing
Mobile computing is one of the most recent major milestones in the history of
computers. Many smart phones today have higher processor speeds and more
memory than desktop PCs had even ten years ago. With phones like the iPhone
and the Motorola Droid, it’s becoming possible to perform most of the functions
once reserved for desktop PCs from anywhere.
The Droid is a Smartphone capable of basic computing tasks such as emailing
and web browsing. Mobile computing really got its start in the 1980s, with the
pocket PCs of the era. These were something like a cross between a calculator, a
small home computer and a PDA. They largely fell out of favor by the 1990s.
During the 1990s, PDAs (Personal Digital Assistant) became popular.

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A number of manufacturers had models, including Apple and Palm. The main
feature PDAs had that not all pocket PCs had was a touch screen interface. PDAs
are still manufactured and used today, though they’ve largely been replaced by
smart phones.
Smartphone’s have truly revolutionized mobile computing. Most basic computing
functions can now be done on a Smartphone, such as email, browsing the
internet, and uploading photos and videos.
Late 2000s: Net books
Another recent progression in computing history is the development of net book
computers. Net books are smaller and more portable than standard laptops, while
still being capable of performing most functions average computer users need
(using the Internet, managing email, and using basic office programs). Some
netbooks go as far as to have not only built-in Wife capabilities, but also built-in
mobile broadband connectivity options.
The Asus Eee PC 700 was the first netbook to enter mass production.
The first mass-produced net book was the Asus Eee PC 700, released in 2007.
They were originally released in Asia, but were released in the US not long
afterward.
Other manufacturers quickly followed suit, releasing additional models
throughout 2008 and 2009.
One of the main advantages of netbooks is their lower cost (generally ranging
from around US$200-$600). Some mobile broadband providers have even
offered net books for free with an extended service contract. Comcast also had a
promotion in 2009 that offered a free net book when you signed up for their cable
internet services.
Most net books now come with Windows or Linux installed, and soon, there will
be Android-based net books available from Asus and other manufacturers.
The history of computing spans nearly two centuries at this point, much longer
than most people realize. From the mechanical computers of the 1800s to the
room-sized mainframes of the mid-20th century, all the way up to the net books
and smart phones of today, computers have evolved radically throughout their
history. The past 100 years have brought technological leaps and bounds to
computing, and there’s no telling what the next 100 years might bring.
The Invention of Computers

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"Who invented the computer?" is not a question with a simple
answer. The real answer is that many inventors contributed to the
history of computers and that a computer is a complex piece of
machinery made up of many parts, each of which can be
considered a separate invention.
This series covers many of the major milestones in computer history (but not all
of them) with a concentration on the history of personal home computers.
Computer History
Year/Enter
Computer History
Inventors/Inventions
Computer History
Description of Event
1936
Konrad Zuse - Z1
Computer
First freely programmable
computer.
1942
John Atanasoff &
Clifford Berry
ABC Computer
Who was first in the computing
biz is not always as easy as
ABC.
1944
Howard Aiken &
Grace Hopper
Harvard Mark I
Computer
The Harvard Mark 1 computer.
1946
John Presper Eckert
& John W. Mauchly
ENIAC 1 Computer
20,000 vacuum tubes later...
1948
Frederic Williams &
Tom Kilburn
Manchester Baby
Computer & The
Williams Tube
Baby and the Williams Tube
turn on the memories.
1947/48
John Bardeen, Walter
Brattain & Wiliam
Shockley
The Transistor
No, a transistor is not a
computer, but this invention
greatly affected the history of
computers.
1951
John Presper Eckert
& John W. Mauchly
UNIVAC Computer
First commercial computer &
able to pick presidential winners.
1953
International
Business Machines
IBM 701 EDPM
IBM enters into 'The History of
Computers'.

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Computer
1954
John Backus & IBM
FORTRAN
Computer
Programming
Language
The first successful high level
programming language.
1955
(In Use 1959)
Stanford Research
Institute, Bank of
America, and General
Electric
ERMA and MICR
The first bank industry computer
- also MICR (magnetic ink
character recognition) for
reading checks.
1958
Jack Kilby & Robert
Noyce
The Integrated
Circuit
Otherwise known as 'The Chip'
1962
Steve Russell & MIT
Spacewar Computer
Game
The first computer game
invented.
1964
Douglas Engelbart
Computer Mouse &
Windows
Nicknamed the mouse because
the tail came out the end.
1969 ARPAnet The original Internet.
1970
Intel 1103 Computer
Memory
The world's first available
dynamic RAM chip.
1971
Faggin, Hoff &
Mazor
Intel 4004 Computer
Microprocessor
The first microprocessor.
1971
Alan Shugart &IBM
The "Floppy" Disk
Nicknamed the "Floppy" for its
flexibility.
1973
Robert Metcalfe &
Xerox
The Ethernet
Computer
Networking
Networking.
1974/75
Scelbi & Mark-8
Altair & IBM 5100
Computers
The first consumer computers.

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1976/77
Apple I, II & TRS-
80 & Commodore
Pet Computers
More first consumer computers.
1978
Dan Bricklin & Bob
Frankston
VisiCalc
Spreadsheet
Software
Any product that pays for itself
in two weeks is a surefire
winner.
1979
Seymour Rubenstein
& Rob Barnaby
WordStar Software
Word Processors.
1981
IBM
The IBM PC - Home
Computer
From an "Acorn" grows a
personal computer revolution
1981
Microsoft
MS-DOS Computer
Operating System
From "Quick And Dirty" comes
the operating system of the
century.
1983
Apple Lisa
Computer
The first home computer with a
GUI, graphical user interface.
1984
Apple Macintosh
Computer
The more affordable home
computer with a GUI.
1985 Microsoft Windows
Microsoft begins the friendly
war with Apple.
What is a Computer !
A computer is an electronic machine that accepts information, stores it until the
information is needed, processes the information according to the instructions
provided by the user, and finally returns the results to the user. The computer can
store and manipulate large quantities of data at very high speed, but a computer
cannot think. A computer makes decisions based on simple comparisons such as
one number being larger than another. Although the computer can help solve a
tremendous variety of problems, it is simply a machine. It cannot solve problems
on its own.
COMPUTER stands for:
• C - Common

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• O - Oriented
• M - Machine
• P - Particularly
• U - Used For
• T - Trade
• E - Education And
• R - Research
Characteristics of Computers !
Computer has the following characteristics:
• Automation
• Speed
• Accuracy
• Continuity
• Memory
• Storage power
• Versatility
• Reliability
• Micro size
• Thoughtless
•
Classification of Computers !
1. Mainframe Computers
2. Minicomputers
3. Microcomputers
4. Supercomputers
Mainframe computers are very large, often filling an entire room. They can store
enormous of information, can perform many tasks at the same time, can
communicate with many users at the same time, and are very expensive. . The
price of a mainframe computer frequently runs into the millions of dollars.
Mainframe computers usually have many terminals connected to them. These
terminals look like small computers but they are only devices used to send and
receive information from the actual computer using wires. Terminals can be
located in the same room with the mainframe computer, but they can also be in
different rooms, buildings, or cities. Large businesses, government agencies, and
universities usually use this type of computer.
Minicomputers are much smaller than mainframe computers and they are also
much less expensive. The cost of these computers can vary from a few thousand
dollars to several hundred thousand dollars. They possess most of the features
found on mainframe computers, but on a more limited scale. They can still have

17. 17
many terminals, but not as many as the mainframes. They can store a tremendous
amount of information, but again usually not as much as the mainframe. Medium
and small businesses typically use these computers.
Microcomputers are the types of computers we are using in your classes at Floyd
College. These computers are usually divided into desktop models and laptop
models. They are terribly limited in what they can do when compared to the
larger models discussed above because they can only be used by one person at a
time, they are much slower than the larger computers, and they cannot store
nearly as much information, but they are excellent when used in small businesses,
homes, and school classrooms. These computers are inexpensive and easy to use.
They have become an indispensable part of modern life.
Computer Architecture
Computer architecture refers to the definition of basic attributes of hardware
components and their interconnections, in order to achieve certain specified goals
in terms of functions and performance. The attributes may include, for example
the instruction set , data representation, I/O mechanisms, etc. The architecture
basically defines the logical structure of a computer system.
The Central Processing Unit (CPU) is the "brain" of the computer, it is the
'computer' in computer. Without the CPU, you have no computer. Computer
CPU's (processors) are composed of thin layers of thousands of transistors.
Transistors are tiny, nearly microscopic bits of material that will block electricity
when the the electricity is only a weak charge, but will allow the electricity pass
through when the electricity is strong enough. The transistors transition from
being a non-conductor (resist the electricity) to a conductor (they conduct
electricity) when the electrical change is strong enough. The material the
transistor is made of loses its resistance to electricity and becomes a conductor
when the electricity gets strong enough. The ability of these materials (called
semi-conductors) to transition from a non-conducting to a conducting state allows
them to take two electrical inputs and produce a different output only when one
or both inputs are switched on. A computer CPU is composed of millions (and
soon billions) of transistors. Because CPU's are so small, they are often referred
to as microprocessors. So, the terms processor, microprocessor and CPU are
interchangeable. AMD, IBM, Intel, Motorola, SGI and Sun are just a few of the
companies that make most of the CPU's used for various kinds of computers
including home desktops, office computers, mainframes and supercomputers.
Modern CPU's are what are called 'integrated chips'. The idea behind an
integrated chip is that several types of components are integrated into a single
piece of silicon (a single CPU), such as one or more execution cores, arithmetic

18. 18
logic unit (ALU) or 'floating point' processor, registers, instruction memory,
cache memory and the input/output controller (bus controller).
Each transistor is a receives a set of inputs and produces output. When one or
more of the inputs receive electricity, the combined charge changes the state of
the transistor internally and you get a result out the other side. This simple effect
of the transistor is what makes it possible for the computer to count and perform
logical operations, all of which we call processing.
A modern computer's CPU usually contains an execution core with two or more
instruction pipelines, a data and address bus, a dedicated arithmetic logic unit
(ALU, also called the math co-processor), and in some cases special high-speed
memory for caching program instructions from RAM.
Generations
CPU manufacturers engineer new ways to do processing that requires some
significant re-engineering of the current chip design. When they create this new
design that changes the number of bits the chip can handle, or some other major
way in which the chip performs its job, they are creating a new generation of
processors. As of the time this tutorial was last updated (2008), there were seven
generations of chips, with an eighth on the drawing board.
CPU Components
A lot of components go into building a modern computer processor and just what
goes in changes with every generation as engineers and scientists find new, more
efficient ways to do old tasks.
• Execution Core(s)
• Data Bus
• Address Bus
• Math Co-processor
• Instruction sets / Microcode
• Multimedia extensions
• Registers
• Flags
• Pipelining
• Memory Controller
• Cache Memory (L1, L2 and L3)
Block Diagram of Computer and its Explanation?

19. 19
Block Diagram of Computer :
A computer can process data, pictures, sound and graphics. They can solve highly
complicated problems quickly and accurately.
Input Unit:
Computers need to receive data and instruction in order to solve any problem.
Therefore we need to input the data and instructions into the computers. The
input unit consists of one or more input devices. Keyboard is the one of the most
commonly used input device. Other commonly used input devices are the mouse,
floppy disk drive, magnetic tape, etc. All the input devices perform the following
functions.
•Accept the data and instructions from the outside world.
•Convert it to a form that the computer can understand.
•Supply the converted data to the computer system for further processing.
Storage Unit:
The storage unit of the computer holds data and instructions that are entered
through the input unit, before they are processed. It preserves the intermediate
and final results before these are sent to the output devices. It also saves the data
for the later use. The various storage devices of a computer system are divided
into two categories.
1. Primary Storage: Stores and provides very fast. This memory is generally
used to hold the program being currently executed in the computer, the data being
received from the input unit, the intermediate and final results of the program.
The primary memory is temporary in nature. The data is lost, when the computer
is switched off. In order to store the data permanently, the data has to be
transferred to the secondary memory. The cost of the primary storage is more

20. 20
compared to the secondary storage. Therefore most computers have limited
primary storage capacity.
2. Secondary Storage: Secondary storage is used like an archive. It stores
several programs, documents, data bases etc. The programs that you run on the
computer are first transferred to the primary memory before it is actually run.
Whenever the results are saved, again they get stored in the secondary memory.
The secondary memory is slower and cheaper than the primary memory. Some of
the commonly used secondary memory devices are Hard disk, CD, etc.,
Memory Size:
All digital computers use the binary system, i.e. 0’s and 1’s. Each character or a
number is represented by an 8 bit code.
The set of 8 bits is called a byte.
A character occupies 1 byte space.
A numeric occupies 2 byte space.
Byte is the space occupied in the memory.
The size of the primary storage is specified in KB (Kilobytes) or MB (Megabyte).
One KB is equal to 1024 bytes and one MB is equal to 1000KB. The size of the
primary storage in a typical PC usually starts at 16MB. PCs having 32 MB,
48MB, 128 MB, 256MB memory are quite common.
Output Unit:
The output unit of a computer provides the information and results of a
computation to outside world. Printers, Visual Display Unit (VDU) are the
commonly used output devices. Other commonly used output devices are floppy
disk drive, hard disk drive, and magnetic tape drive.
Arithmetic Logical Unit:
All calculations are performed in the Arithmetic Logic Unit (ALU) of the
computer. It also does comparison and takes decision. The ALU can perform
basic operations such as addition, subtraction, multiplication, division, etc and
does logic operations viz, >, <, =, ‘etc. Whenever calculations are required, the
control unit transfers the data from storage unit to ALU once the computations
are done, the results are transferred to the storage unit by the control unit and then
it is send to the output unit for displaying results.
There are 4 types of arithmetic operations that the CPU can perform...
1. Addition
2. Subtraction
3. Multiplication
4. Division

21. 21
The ALU will also perform logical operations. This is simply a comparison
operation. Does A = B? It can compare numbers, letters, and some special
characters. The CPU will then take action based on the outcome of this operation.
This is central to the CPU and allows it to be able to tell you things like...
Control Unit:
It controls all other units in the computer. The control unit instructs the input unit,
where to store the data after receiving it from the user. It controls the flow of data
and instructions from the storage unit to ALU. It also controls the flow of results
from the ALU to the storage unit. The control unit is generally referred as the
central nervous system of the computer that control and synchronizes its working.
Central Processing Unit:
The control unit and ALU of the computer are together known as the Central
Processing Unit (CPU). The CPU is like brain performs the following functions:
• It performs all calculations.
• It takes all decisions.
• It controls all units of the computer.
A PC may have CPU-IC such as Intel 8088, 80286, 80386, 80486, Celeron,
Pentium, Pentium Pro, Pentium II, Pentium III, Pentium IV, Dual Core, and
AMD etc.
Related Posts:
• Internal parts of CPU
• What is RAM and what are its functions
• Classification of computers based on memory size
• What is an operating system? What are its functions?
• What is a hard disk? What are its features
Input/output Devices
Contents:
I. Introduction : The computer will be of no use unless it is able to
communicate with the outside world. Input/output devices are required for users
to communicate with the computer. In simple terms, input devices bring
information INTO the computer and output devices bring information OUT of a
computer system. These input/output devices are also known as peripherals since
they surround the CPU and memory of a computer system.
II. Input Devices :- Keyboard, mouse, joystick, scanners, digital camera, bar code
reader, touch Screen, Speech input device (microphone)
III. Output Devices :- a. Monitor , Speaker, Printers ( different types)

22. 22
(a) Keyboard
It is a text base input device that allows the user to input alphabets, numbers and
Other characters. It consists of a set of keys mounted on a board.
Alphanumeric Keypad
It consists of keys for English alphabets, 0 to 9 numbers, and special characters
like +
−/ * ( ) etc.
Function Keys
There are twelve function keys labeled F1, F2, and F3… F12. The functions
assigned to these keys differ from one software package to another. These keys
are also user programmable keys.
Special-function Keys
These keys have special functions assigned to them and can be used only for
those
specific purposes. Functions of some of the important keys are defined below.
Enter : It is similar to the ‘return’ key of the typewriter and is used to execute
a command or program.
Spacebar : It is used to enter a space at the current cursor location.
Backspace : This key is used to move the cursor one position to the left and
also delete the character in that position.
Delete : It is used to delete the character at the cursor position.
Insert : Insert key is used to toggle between insert and overwrite mode
during data entry.
Shift : This key is used to type capital letters when pressed along with an
alphabet key. Also used to type the special characters located on the upper-side
of a key that has two characters defined on the same key.
Caps Lock : Cap Lock is used to toggle between the capital lock features. When
‘on’, it locks the alphanumeric keypad for capital letters input only.

23. 23
Tab : Tab is used to move the cursor to the next tab position defined in the
document. Also,it is used to insert indentation into a document.
Ctrl : Used with combination key ex Ctrl S for Save the File
Function Keys :- Numeric Keypad , Cursor Movement, Keys , Alphanumeric
Keypad/
Special-function Keys :- Control key is used in conjunction with other keys to
provide additional functionality on the keyboard.
Alt : Also like the control key, Alt key is always used in combination with
other keys to perform specific tasks.
Esc : This key is usually used to negate a command. Also used to cancel or
abort executing programs.
Numeric Keypad : Numeric keypad is located on the right side of the keyboard
and consists of keys having numbers (0 to 9) and mathematical operators (+ −* /)
defined on them. This keypad is provided to support quick entry for numeric data.
Cursor Movement Keys : These are arrow keys and are used to move the cursor
in the direction indicated by the arrow (up, down, left, right).
(b) Mouse : The mouse is a small device used to point to a particular place on
the screen and select in order to perform one or more actions. It can be used to
select menu commands, size windows, start programs etc. The most conventional
kind of mouse has two buttons on top: the left one being used most frequently.
Mouse Actions
Left Click : Used to select an item.
Double Click : Used to start a program or open a file.
Right Click : Usually used to display a set of commands.
Drag and Drop : It allows you to select and move an item from one location to
another. To achieve this place the cursor over an item on the screen, click the left
mouse button and while holding the button down move the cursor to where you
want to place the item, and then release it.
(c) Joystick
The joystick is a vertical stick which moves the graphic cursor in a direction the
stick is moved. It typically has a button on top that is used to select the option

24. 24
pointed by the cursor. Joystick is used as an input device primarily used with
video games, training simulators and controlling robots
(d) Scanner
Scanner is an input device used for direct data entry from the source document
into the computer system. It converts the document image into digital form so
that it can be fed into the computer. Capturing information like this reduces the
possibility of errors typically experienced during large data entry. Hand-held
scanners are commonly seen in big stores to scan codes and price information for
each of the items. They are also termed the bar code readers.
(e) Bar codes
A bar code is a set of lines of different thicknesses that represent a number. Bar
Code Readers are used to input data from bar codes. Most products in shops have
bar codes on them .Bar code readers work by shining a beam of light on the lines
that make up the bar code and detecting the amount of light that is reflected back.
(f) Light Pen
It is a pen shaped device used to select objects on a display screen. It is quite like
the mouse (in its functionality) but uses a light pen to move the pointer and select
any object on the screen by pointing to the object. Users of Computer Aided
Design (CAD) applications commonly use the light pens to directly draw on
screen.
(g) Touch Screen
It allows the user to operate/make selections by simply touching the display
screen. Common examples of touch screen include information kiosks, and bank
ATMs.
(h) Digital camera
A digital camera can store many more pictures than an ordinary camera. Pictures
taken using a digital camera are stored inside its memory and can be transferred
to a
computer by connecting the camera to it. A digital camera takes pictures by
converting the light passing through the lens at the front into a digital image.
(i) The Speech Input Device

25. 25
The “Microphones - Speech Recognition” is a speech Input device. To operate it
we require using a microphone to talk to the computer. Also we need to add a
sound card to the computer. The Sound card digitizes audio input into 0/1s .A
speech recognition program can process the input and convert it into machine-
recognized commands or input.
Output Devices
(a) Monitor
Monitor is an output device that resembles the television screen and uses a
Cathode Ray Tube (CRT) to display information. The monitor is associated with
a keyboard for manual input of characters and displays the information as it is
keyed in. It also displays the program or application output. Like the television,
monitors are also available in different sizes.
(b) Liquid Crystal Display (LCD)
LCD was introduced in the 1970s and is now applied to display terminals also. Its
advantages like low energy consumption, smaller and lighter have paved its way
for usage in portable computers (laptops).
(c) Printer
Printers are used to produce paper (commonly known as hardcopy) output. Based
on the technology used, they can be classified as Impact or Non-impact printers.
Impact printers use the typewriting printing mechanism wherein a hammer strikes
the paper through a ribbon in order to produce output. Dot-matrix and Character
printers fall under this category. Non-impact printers do not touch the paper while
printing. They use chemical, heat or electrical signals to etch the symbols on
paper. Inkjet, DeskJet, Laser, Thermal printers fall under this category of printers.
When we talk about printers we refer to two basic qualities associated with
printers: resolution, and speed. Print resolution is measured in terms of number of
dots per inch (dpi). Print speed is measured in terms of number of characters
printed in a unit of time and is represented as characters-per-second (cps), lines-
per-minute (lpm), or pages-per-minute (ppm).
(d) Plotter
Plotters are used to print graphical output on paper. It interprets computer
commands and makes line drawings on paper using multicolored automated pens.
It is capable of producing graphs, drawings, charts, maps etc. Computer Aided
Engineering (CAE) applications like CAD (Computer Aided Design) and CAM
(Computer Aided Manufacturing) are typical usage areas for
plotters.

26. 26
(e) Audio Output: Sound Cards and Speakers:
The Audio output is the ability of the computer to output sound. Two components
are needed: Sound card – Plays contents of digitized recordings, Speakers –
Attached to sound card.
Summary:
The Chapter has given an introduction to the Input/output devices. It gives a
detailed listing of the various types of input devices and the output devise.
First Generation Computers:
The First Generation Computers was marked by the use of vacuum tubes for the
electronic components and by the use of electrostatic tubes or mercury delay lines
for storage.
The first computers used vacuum tubes for circuitry and magnetic drums for
memory, and were often enormous, taking up entire rooms. They were very
expensive to operate and in addition to using a great deal of electricity, generated
a lot of heat, which was often the cause of malfunctions. First generation
computers relied on machine language to perform operations, and they could only
solve one problem at a time. Input was based on punched cards and paper tape,
and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing
devices. The UNIVAC was the first commercial computer delivered to a business
client, the U.S. Census Bureau in 1951. Their outstanding features were:-
1. Very expensive, poor reliability, slow input/output.
2. Quite large, generated lot of heat and required special housing.
3. The medium of internal storage was magnetic drum.
4. Punched cards and paper tapes were used for secondary storage.
5. Continuous maintenance is required; produces lot of heat hence requires
special air conditioning.
6. Applications-pay roll and other single applications in large companies.
7. Uses batch processing technology, to process the data.
Ex. In 1949 – at Cambridge University EDSAC (Electronic Delayed Storage
Automatic Calculator was developed).
In 1952 at Pennsylvania University, EDVAC (Electronic Discrete Variable
Automatic Calculator) was developed.
In 1951, UNIVAC-I (Universal Automatic Computer) was developed.

27. 27
The First Generation (1951-1959)
• 1951: Mauchly and Eckert built the UNIVAC I, the first computer designed and
sold commercially, specifically for business data-processing applications.
• 1950s : Dr. Grace Murray Hopper developed the UNIVAC I compiler.
• 1957 : The programming language FORTRAN (FORmula TRANslator) was
designed by John Backus, an IBM engineer.
• 1959 : Jack St. Clair Kilby and Robert Noyce of Texas Instruments
manufactured the first integrated circuit, or chip, which is a collection of tiny
little transistors.
Second Generation Computers:
The second generation computers are initially marked by either magnetic drum or
magnetic core storage and later by the use of the transistor in the place of vacuum
tubes.
Transistors replaced vacuum tubes and ushered in the second generation of
computers. The transistor was invented in 1947 but did not see widespread use in
computers until the late 50s. The transistor was far superior to the vacuum tube,
allowing computers to become smaller, faster, cheaper, more energy-efficient and
more reliable than their first-generation predecessors. Though the transistor still
generated a great deal of heat that subjected the computer to damage, it was a vast
improvement over the vacuum tube. Second-generation computers still relied on
punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to
symbolic, or assembly, languages, which allowed programmers to specify
instructions in words. High-level programming languages were also being
developed at this time, such as early versions of COBOL and FORTRAN. These
were also the first computers that stored their instructions in their memory, which
moved from a magnetic drum to magnetic core technology.
Main features of the second generation computers are:
1. Magnetic core was used as primary storage device and tape as secondary
storage.
2. Used transistor circuits, hence the size of the computer was small compared to
that of first generation computer.
3. Greater reliability and higher speed, when compared to that of first generation
computers.
4. Uses high level procedural languages viz., FORTRAN (Formula Translator)
1954-57, COBOL (Common Business Oriented Language) 1957-61.
5. They are small, faster and required less power to operate.

28. 28
6. Applications: Payroll, Inventory, Accounts Receivable, in large and medium
sized companies:
Ex: IBM 700, 1401; ATLAS; ICL 1901
The Second Generation (1959-1965)
• 1960s : Gene Amdahl designed the IBM System/360 series of mainframe (G)
computers, the first general-purpose digital computers to use integrated circuits.
• 1961: Dr. Hopper was instrumental in developing the COBOL (Common
Business Oriented Language) programming language.
• 1963 : Ken Olsen, founder of DEC, produced the PDP-I, the first minicomputer
(G).
• 1965 : BASIC (Beginners All-purpose Symbolic Instruction Code)
programming language developed by Dr. Thomas Kurtz and Dr. John Kemeny.
Third Generation Computers (1965-1971):
The arrival of the third generation in the mid 1960’s proved to be an important
milestone in the evolution of computers. The development of the integrated
circuit was the hallmark of the third generation of computers. Transistors were
miniaturized and placed on silicon chips, called semiconductors, which
drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation
computers through keyboards and monitors and interfaced with an operating
system, which allowed the device to run many different applications at one time
with a central program that monitored the memory. Computers for the first time
became accessible to a mass audience because they were smaller and cheaper
than their predecessors.
The following are the features of this generation:
1. Further reductions in size of computer.
2. The cost/performance factor has improved significantly.
3. Increased internal core memory capacity.
4. Processor speeds are rated in nano seconds.
5. The use of high level languages became common e.g.: COBOL, FORTRAN
and PL/I.
6. Multiprogramming operating system was developed.
7. Magnetic disk was used as secondary storage.
8. Transistors were replaced with integrated circuits – hence increased
miniaturization.
9. Computers were capable of performing both scientific and business tasks with
high speed and reliability.

29. 29
10. Input and Output devices are improved.
11. Applications: Order Processing, air line reservation, real-time inventory
control etc.
12. Uses online, real time processing and multiprogramming operating system.
Ex: IBM/360/370; NCR 395; Burroughs-B6500.
The Third Generation (1965-1971)
• 1969 : The Internet is started. (See History of the Internet)
• 1970 : Dr. Ted Hoff developed the famous Intel 4004 microprocessor (G) chip.
• 1971: Intel released the first microprocessor, a specialized integrated circuit
which was able to process four bits of data at a time. It also included its own
arithmetic logic unit. PASCAL, a structured programming language, was
developed by Niklaus Wirth.
Fourth Generation Computers:
The introduction of micro technology and significant software developments,
Micro technology gave rise to the development of micro computers, work
processors and intelligent terminals.
The microprocessor brought the fourth generation of computers, as thousands of
integrated circuits were built onto a single silicon chip. What in the first
generation filled an entire room could now fit in the palm of the hand. The Intel
4004 chip, developed in 1971, located all the components of the computer - from
the central processing unit and memory to input/output controls - on a single
chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple
introduced the Macintosh. Microprocessors also moved out of the realm of
desktop computers and into many areas of life as more and more everyday
products began to use microprocessors.
As these small computers became more powerful, they could be linked together
to form networks, which eventually led to the development of the Internet. Fourth
generation computers also saw the development of GUIs, the mouse and
handheld devices.
Features of this fourth generation are:
1. Integrated Circuits are replaced with very large scale integrated circuits.
2. Semiconductors used as primary storage.
3. Dramatic decrease in the size of computer – development of micro computers,
personal computer.
4. Development of electronic spread sheet.
5. Development of database management systems.

30. 30
6. Development of distributed data bases and virtual storage operating system.
7. Increased use of data communications and computer networks.
8. Increased use of Cathode Ray Tube (CRT) terminals.
9. The computers are compact, faster, and cheaper and are more reliable.
10. Application : Corporate modeling, decision support system, electronic funds
transfer, electronic spread sheet, word processing and small business
applications.
The Fourth Generation (1971-Present)
• 1975 : Ed Roberts, the "father of the microcomputer" designed the first
microcomputer, the Altair 8800, which was produced by Micro Instrumentation
and Telemetry Systems (MITS). The same year, two young hackers, William
Gates and Paul Allen approached MITS and promised to deliver a BASIC
compiler. So they did and from the sale, Microsoft was born.
• 1976 : Cray developed the Cray-I supercomputer (G). Apple Computer, Inc was
founded by Steven Jobs and Stephen Wozniak.
• 1977 : Jobs and Wozniak designed and built the first Apple II microcomputer.
• 1970 : 1980: IBM offers Bill Gates the opportunity to develop the operating
system for its new IBM personal computer. Microsoft has achieved tremendous
growth and success today due to the development of MS-DOS. Apple III was
also released.
• 1981 : The IBM PC was introduced with a 16-bit microprocessor.
• 1982 : Time magazine chooses the computer instead of a person for its
"Machine of the Year."
• 1984 : Apple introduced the Macintosh computer, which incorporated a unique
graphical interface, making it easy to use. The same year, IBM released the 286-
AT.
• 1986 : Compaq released the DeskPro 386 computer, the first to use the 80036
microprocessor.
• 1987 : IBM announced the OS/2 operating-system technology.
• 1988 : A nondestructive worm was introduced into the Internet network
bringing thousands of computers to a halt.
• 1989 : The Intel 486 became the world's first 1,000,000 transistor
microprocessor.
• 1993s: The Energy Star program, endorsed by the Environmental Protection
Agency (EPA), encouraged manufacturers to build computer equipment that met
power consumption guidelines. When guidelines are met, equipment displays the
Energy Star logo. The same year, Several companies introduced computer
systems using the Pentium microprocessor from Intel that contains 3.1 million
transistors and is able to perform 112 million instructions per second (MIPS)
www.Onlinemca.com

31. 31
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in
development, though there are some applications, such as voice recognition, that
are being used today. The use of parallel processing and superconductors is
helping to make artificial intelligence a reality. Quantum computation and
molecular and nanotechnology will radically change the face of computers in
years to come. The goal of fifth-generation computing is to develop devices that
respond to natural language input and are capable of learn The Fifth Generation
Computer Systems project (FGCS) was an initiative by Japan's Ministry of
International Trade and Industry, begun in 1982, to create a "fifth generation
computer" (see history of computing hardware) which was supposed to perform
much calculation utilizing massive parallelism. It was to be the end result of a
massive government/industry research project in Japan during the 1980s. It aimed
to create an "epoch-making computer" with supercomputer-like performance and
usable artificial intelligence capabilities.
The term fifth generation was intended to convey the system as being a leap
beyond existing machines. Computers using vacuum tubes were called the first
generation; transistors and diodes, the second; ICs, the third; and those using
microprocessors, the fourth. Whereas previous computer generations had focused
on increasing the number of logic elements in a single CPU, the fifth generation,
it was widely believed at the time, would instead turn to massive numbers of
CPUs for added performance and self-organization.
Future Computers (since 1985):
By the end of 1982, the computers were used every where, in automobiles,
appliances, business information systems, and military hardware. With electronic
technology advancing rapidly, the use of computers expected to grow in coming
years. With the increased user requirements, the technology has evolved with
outstanding features.
Some of the important features of the future computers are:
1. Future Computers use organic chips to process the data.
2. Both the software and hardware costs are decreasing at a high speed, so that
the computers can be used by every common man (within the reach of common
man).
3. Increased miniaturization and price/performance ratio.
4. The computers have high speed, and storage capacity.
5. Has the capacity to make decisions. (Auto decisions).
6. Uses non procedural software, which is very user friendly.

32. 32
7. Applications: Artificial Intelligence, Robots, Large Scale Corporate modeling,
oil exploration, star wars system and personal robots.
Advantage And Disadvantages
The main advantages of computerizing the activities of business organization are
as follows:
Advantages:
Speed: Computerization helps in processing the data placed in several data files
in no time. This is possible due to the high speed of computers for processing
data and CPU of the computer works at the speed of electricity which is the
highest ever attainable speed.
Accuracy: The data processed by the computer are highly accurate. The programs
written on the system checks and controls data before and during processing. It
detects invalid data and ensures high degree of accuracy and reliability of output
reports.
Flexibility: The modern digital computers can be used for a variety of purposes.
E.g. online processing, multiprogramming etc.
Choice of Configuration: Wide ranges of peripherals are available for many
computer systems, which allow business organization to select those which most
suit its processing requirements.
1. Storage capacity: Large volumes of data can be conveniently stored,
accessed and altered.
2. Management information: They can be used to provide useful information
of management for control and decision making.
3. Data Processing: Computer has lifted the heavy data processing constraint
with the manual system and has opened up new avenues for planning, control and
data experimentation.
4. Volume: Computers can store volumes of data and can retrieve the
desired information quickly. This is very useful in the areas like insurance, bank
accounts etc where large number of documents is handled every day.
5. Database: Computer facilities the establishment of database. Such a
database integrates data records and reduces data redundancy.
6. Reduction in paper work: The use of computers for data processing has
helped the management of business organizations to cope with increasing
problem of paper handling. The computers have speeded up the process and have
eliminated the paper needs through the storage of data in elaborately constructed
data bases and files.
7. Reduced cost: Though the initial investment for installing a computer is
high, but it substantially reduces the cost of each of its transaction. Cost reduction
occurs due to processing of huge data and record keeping.

33. 33
8. Facilitates report preparation: Computer facilitates the preparation of
various types of reports required by organizational executives for the purpose of
decision making and control.
9. Reduce the space requirements: The use of computer for office activities
reduces the requirements of office space which otherwise is required.
10. Reduces the manpower requirement: The number of persons required for
performing various organizational activities will be reduced by using a computer
system.
11. Increased ability to perform computations: Computers perform
computations with a very high speed.
Diligence: Being a machine, it does not suffer from boredom, tiredness or lack of
concentration, even if millions of computations are to be performed by a
computer. It performs the calculations with same accuracy and speed.
Disadvantages:
1. Installing the computer requires a grueling and expensive task of system
analysis and design. There is a scarcity of computer professionals to do this.
2. Management tends to treat computer like ordinary equipment Viz., air
conditioning equipment, and keep themselves aloof from the system development
effort. Computer pervades the working of the entire organization and unless
managements involve themselves fully during the system development effort and
the employees, the customers, the vendors etc. are willing to accept the
computerized system and its outputs the system is bound to prove a failure.
3. The initial investment can be very high though this can be mitigated to
some extent by the rental and tax concessions.
4. Since the lead-time of installing is long and the hardware technology is a
rapidly advancing field, some of the peripherals/components may be rendered
obsolete before even they are installed.
5. The need to obtain stand by facilities in the event of breakdown of any
computerized systems. Manual systems, though slow, are vastly flexible. If the
format of a report, for example has to be changed, it can be readily done by
communicating the necessary instruction to the concerned staff whereas in a
computerized system, this would have to go through all the stages of systems
analysis and design before it is effected
System Software And Application Software
Software is a set of instructions, programs which enable the computer to perform
specified task. In other words, software is nothing but binary code instructions
which control the hardware.
In most of the organizations the computer is a valuable resource. Among the
resources that a computer has are processing time, storage space, printers,
terminals and information. The management of these resources is performed
largely by a type of system software called an operating system. When users
interact with the computer the interaction is with system software.

34. 34
There are two broad categories of software, system software and application
software. System software is a set of programs that manage the resources of a
computer system, so that they are used in an optimal fashion, provide routine
services such as copying data from one file to another and assist in the
development of applications programs.
System software consists of programs that assist the computer in the efficient
control, support, development and execution of application programs.
Application software on the other hand, performs specific tasks for the computer
user.
System software:
They can be broadly classified in to three types.
1. System control programs control the execution of programs, manage the
storage and processing resources of the computer and perform other management
and monitoring functions. Other examples are DBMS and communication
monitors.
2. System support programs provide routine service functions to the other
computer programs and computer users. Ex. Libraries, utilities, job accounting
etc.
3. System development programs assist in the creation of application
programs.
System programs are developed and sold by both computer companies and
specialized software firms.
Application Software:
It is a program written for, or by, a user to perform a specific job. General
purpose application software such as electronic spreadsheet has a wide
application. Specific purpose application software, such as payroll and sales
analysis is used only for the application for which it is designed.
The system software controls the execution of the application software and
provides other support functions such as data storage.
What is an operating system? What are its functions?
The operating system is a program that acts as an interface between the user and
the hardware. It is a collection of programs that coordinates the operations of
computer hardware and software.
Functions of an operating system:
1. Starting the Computer: In most computers, the BIOS and the diagnostic
routines are contained in ROM. They are permanently available to other
programs to check equipment and perform input/output tasks. In addition, ROM
contains a bootstrap loader program that is used to start a computer.

35. 35
The remainder of the operating system is contained in secondary memory.
When the computer is turned on, it automatically begins to execute the boot
program. This program first runs diagnostic programs to check the status of RAM
and of each of the attached system devices.
The boot program then reads in the operating system executive program from the
disk. The layout of the memory at this stage is shown in figure.
2. Running application programs: To run an application programs such as word
processing program, the user types the name of the program after getting the Dos
prompt on the screen.
Ex C:>WS
The operating system accepts the command WS and reads the program into
RAM. When the application program is in RAM, the operating system executive
program gives control of the computer system to the applications programs. The
computer then executes the application program. When the application program
ends, control is restored to the operating system executive program, which
monitors the keyboard for the users’ next command.
When the application program is running the operating system manages the
allocation of memory. When a user requests that a program be run, the operating
system allocates the memory required for the program instructions and for data.
3. Running utility programs: An operating system includes utility programs that
give the user control over various features of the computer system. The utility
programs are either resident or transient. Resident programs are always present in
RAM; transient program must be read into RAM, as they are requested. Ex.
CON: name of the keyboard, or console.
PRN: name of the printer.
Disk Copy A: B: (copies the contents of the disk in drive A, onto the disk on
drive B)
4. Managing files: Information on the disk is organized into files. A file is
collection of Bytes. What are assembly languages? What are its advantages and
disadvantages? Assembly Languages are structurally similar to machine language
and the programmer uses symbolic names than numerical representation of
operations. This reduces coding time and the amount of information the
programmer has to remember. They use assembler to convert the program in to
machine language (object program).
Assembly languages are also known as symbolic languages as they use symbols
to represent the arithmetic and logical operations. Instead of using machine code
operation numbers, the programmer can use mnemonics and symbolic operands
which are very easy to learn and remember.

36. 36
The programs written in Assembly Languages are machine dependant. They are
not portable. There are many low level languages. They are machine dependant.
For example
IBM – Assembly language.
ICL – System 4 user code.
Honey well – Easy coder.
Advantages:
• Programs written in machine language are replaced by mnemonics which are
easier to remember.
• It is not required to keep track of memory locations.
• Easy to make insertions and deletions.
• Requires fewer instructions to accomplish the same result.
Disadvantages:
• Programs written in such languages cannot be executed on small sized
computers.
• It takes lot of time to code or write the program, as it is more complex in
nature.
• Lack of portability of program between computers of different makes.
What is Hardware
Hardware is best described as a device that is physically connected to your
computer or something that can be physically touched. A perfect example of
hardware is a computer monitor, which is an output device that lets you see what
you're doing on the computer. Without any hardware, your computer would not
exist, and software would not be able to run. In the image to the right, are a
webcam and an example of an external hardware peripheral that allows users to
make videos or pictures and transmit them over the Internet.
What are hardware upgrades?
A hardware upgrade is any new hardware that replaces or adds to old hardware
in the computer. A good example of a common hardware upgrade is a RAM
upgrade, where the user is increasing the computers total memory, which will
increase its overall speed and efficiency. Another good example is doing a video
card upgrade, which is the act of removing the old video card and replacing it
with a new video card that is much more capable than the previously installed
video card, again increasing the capabilities of the computer.
• Additional information with installing computer hardware.
Internal hardware examples
• Blu-Ray, CD-ROM, and DVD
• CPU
• Hard drive

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• Motherboard
• RAM
• Sound card
• Video card
External hardware examples
• Flat-panel, Monitor, and LCD
• Keyboard
• Mouse
• Printer
• Scanner
Computer hardware related questions
• What are the differences between hardware and software?
• Computer hardware questions and answers.
• Full listing of computer hardware devices, support, and help.
Your PC (Personal Computer) is a system, consisting of many components. Some
of those components, like Windows XP, and all your other programs, are
software. The stuff you can actually see and touch, and would likely break if you
threw it out a fifth-story window, is hardware.
Not everybody has exactly the same hardware. But those of you who have a
desktop system, like the example shown in Figure 1, probably have most of the
components shown in that same figure. Those of you with notebook computers
probably have most of the same components. Only in your case the components
are all integrated into a single book-sized portable unit.
Figure 1
The system unit is the actual computer; everything else is called a peripheral
device. Your computer's system unit probably has at least one floppy disk drive,
and one CD or DVD drive, into which you can insert floppy disks and CDs.
There's another disk drive, called the hard disk inside the system unit, as shown
in Figure 2. You can't remove that disk, or even see it. But it's there. And
everything that's currently "in your computer" is actually stored on that hard disk.
(We know this because there is no place else inside the computer where you can
store information!).

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Figure 2
The floppy drive and CD drive are often referred to as drives with removable
media or removable drives for short, because you can remove whatever disk is
currently in the drive, and replace it with another. Your computer's hard disk can
store as much information as tens of thousands of floppy disks, so don't worry
about running out of space on your hard disk any time soon. As a rule, you want
to store everything you create or download on your hard disk. Use the floppy
disks and CDs to send copies of files through the mail, or to make backup copies
of important items.
Random Access Memory (RAM)
There's too much "stuff" on your computer's hard disk to use it all at the same
time. During the average session sitting at the computer, you'll probably use only
a small amount of all that's available. The stuff you're working with at any given
moment is stored in random access memory (often abbreviated RAM, and often
called simply "memory"). The advantage using RAM to store whatever you're
working on at the moment is that RAM is very fast. Much faster than any disk.
For you, "fast" translates to less time waiting and more time being productive.
So if RAM is so fast, why not put everything in it? Why has a hard disk at all?
The answer to that lies in the fact that RAM is volatile. As soon as the computer
is shut off, whether intentionally or by an accidental power outage, everything in
RAM disappears, just as quickly as a light bulb goes out when the plug is pulled.
So you don't want to rely on RAM to hold everything. A disk, on the other hand,
holds its information whether the power is on or off.
The Hard Disk
All of the information that's "in your computer", so to speak, is stored on your
computer's hard disk. You never see that actual hard disk because it's sealed
inside a special housing and needs to stay that way. Unlike RAM, which is
volatile, the hard disk can hold information forever -- with or without electricity.
Most modern hard disks have tens of billions of bytes of storage space on them.
Which, in English, means that you can create, save, and download files for
months or years without using up all the storage space it provides?

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In the unlikely event that you do manage to fill up your hard disk, Windows will
start showing a little message on the screen that reads "You are running low on
disk space" well in advance of any problems. In fact, if that message appears, it
won't until you're down to about 800 MB of free space. And 800 MB of empty
space is equal to about 600 blank floppy disks. That's still plenty of room!
The Mouse
Obviously you know how to use your mouse, since you must have used it to get
here. But let's take a look at the facts and buzzwords anyway. Your mouse
probably has at least two buttons on it. The button on the left is called the
primary mouse button, the button on the right is called the secondary mouse
button or just the right mouse button. I'll just refer to them as the left and right
mouse buttons.
Types Of Hardware
System Unit
• Motherboard
• Hard Disk
• ROM BIOS
• Input Devices
• CPU
• RAM
• CD-ROM
• Output Devices
What is Software?
Software is the general term for information that's recorded onto some kind of
medium. For example, when you go to the video store and rent or buy a tape or
DVD, what you're really getting is the software that's stored on that tape or disk.
You’re VCR or DVD player are hardware devices that are capable of reading the
software from a tape or disk and projecting it onto your TV screen, in the form of
a movie.
Your computer is a hardware device that reads software too. Most of the software
on your computer comes in the form of programs. A program consists of
"instructions" that tell the computer what to do, how to behave. Just as there are
thousands of albums you can buy on CD for your stereo, and thousands of movies
you can buy to play on your VCR or DVD player, there are thousands of
programs that you can buy to run on your computer.

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When you buy a computer, you don't automatically get every program produced
by every software company in the world. You usually get some programs. For
example, when you buy a computer it will probably have an operating system
(like Windows XP) already installed on it.
If you do purchase a specific program, it would be to perform some specific task.
For example, you might use a graphics program to touch up photos, or you might
use a word processing program to write text. You're using your Web browser
program right now to read this text (assuming you're not reading a printed copy
on paper). Just as there are umpteen different brands of
toothpaste, there are umpteen different brands of word
processing programs, graphics programs, and Web browsers.
For example, all graphics programs are designed to help you
work with pictures. But there are many brands of graphics
programs out there, including Adobe Photoshop, Jasc Paint
Shop Pro. Adobe Illustrator, Arcsoft Photo Studio, Corel
Draw, ULead PhotoImpact, PrintShop Photo, and
Macromedia Freehand, just to name a few. As to Web browsers, popular brands
include Microsoft Internet Explorer, MSN Explorer, Netscape Navigator,
America Online, and a few others.
When you purchase a program, you get the program stored on a CD as in the
example shown at left. You may not have seen any boxes containing software
when you bought your computer. That's because the software that came with your
computer has been pre-installed onto your computer's hard disk for you. You
don't need to use the CD to run a program that's already installed on your
computer. You only need to keep the CDs as backups, in case something goes
wrong with your hard disk and you need to re-install the programs.
What Programs Do I Have?
Perhaps you're wondering what programs are installed on your computer. Usually
when you buy a computer, they tell you what programs you're getting with it. So
if you were to go back to the original ad from which you bought your computer,
you'd probably find the names of programs you already have listed there. Though
there's no need to do that, because every program that's currently installed on
your computer is listed in your All Programs menu (assuming you're using
Windows XP).
When you first open the Start menu, the left column lists programs you've used
the most recently (Figure a1). If your computer is brand new, then the programs
listed there will just be some examples.

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Figure a1
That little list of program icons and names on the left side of the menu doesn't
represent all the programs that are currently installed on your computer. Not by a
long shot. The All Programs option on the Start menu provides access to all your
installed programs. When you first click on (or just point to) the All Programs
option, the All Programs menu that appears (Figure a2) will show icons and name
of program groups, as well as some programs.
Figure a2
It's easy to tell the difference between a program and a program group. The
program groups all have the same icon, and all have a right-pointing triangle ()
at their right side. When you click on, or point to, a program group, icons and
names of programs within that group appear on a submenu. The submenu will
contain programs within that group, and perhaps some more program groups. For

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example, Figure a3 shows the result of clicking on the Accessories program
group in the All Programs menu. The submenu that opens contains more program
groups, and specific programs you can run.
Figure a3
Your Start menu won't look exactly like the one shown in the figures, because
different computers have different programs installed. (Just like different people
who own CD players own different CDs).
Running Programs
When you click on the icon for a program, the program opens. Which means the
program appears on the screen, so you can use it. Each program will appear in its
own program window on the Windows desktop. For example, in Figure a4 the
photograph in the background is the Windows desktop. Floating about on top of
that desktop are four different program, each in its own separate program
window.
Figure a4
Elements of Program Windows
While not two programs are exactly alike, most program windows contain certain
similar elements. Stretched across the top of the program window is the title bar,
which usually shows the name of the program that's inside the program window.
Beneath the title bar is the menu bar, which gives you access to the tools and
capabilities of that specific program. Many programs have a toolbar under their

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menu bar. The toolbar provides quick one-click access to frequently-used
commands in the menu bar. The status bar at the bottom of a program provides
general information. Figure a5 shows, in animated form, the title bar, menu bar,
toolbar, and status bar of several different sample programs.
Figure a5
Software is often divided into two categories:
 systems software : Includes the operating system and all the utilities that
enable the computer to function.
 applications software : Includes programs that do real work for users. For
example, word processors, spreadsheets, and database management systems fall
under the category of applications software.
Disk Operating System (DOS)
INTRODUCTION
When the computer starts, it starts the operating system that takes the control of
the machine. An Operating System is a set of programs that help in controlling
and managing the Hardware and the Software resources of a computer system. A
good operating system should have the following features;
1. Help in the loading of programs and data from external sources into the
internal memory before they are executed.
2. Help programs to perform input/output operations, such as;
o Print or display the result of a program on the printer or the screen.
o Store the output data or programs written on the computer in
storage device.
o Communicate the message from the system to the user through the
VDU.
o Accept input from the user through the keyboard or mouse.

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OBJECTIVES
At the end of this lesson, you would be able to;
• explain the concept operating system
• discuss the functions of operating system
• understand the procedures of loading operating system into the memory
• use file management features of operating system
• create separate locations for logically related files
• copy files from one computer to another
• use Windows for File Management
DISK OPERATING SYSTEM
As the name suggests, the operating System is used for operating the system or
the computer. It is a set of computer programs and also known as DOS (Disk
Operating System). The main functions of DOS are to manage disk files, allocate
system resources according to the requirement. DOS provides features essential
to control hardware devices such as Keyboard, Screen, Disk Devices, Printers,
Modems and programs.
Basically, DOS is the medium through which the user and external devices
attached to the system communicate with the system. DOS translate the
command issued by the user in the format that is understandable by the computer
and instruct computer to work accordingly. It also translates the result and any
error message in the format for the user to understand.
WILDCARD CHARACTERS
If you want to carry out a task for a group of files whose names have
something in common, you can use wildcard characters to specify groups of
files. DOS recognize two wildcard characters: asterisk (*) represents one or
more characters that a group of files has in common; and the question
mark (?) represents a single character that a group of files has in common
Internal Commands
BREAK Sets or clears extended CTRL+C checking.
CHDIR Displays the name of or changes the current directory.
CD Displays the name of or changes the current directory.
CLS Clears the screen.

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COPY Copies one or more files to another location.
DATE Displays or sets the date.
DEL Deletes one or more files.
ERASE Deletes one or more files.
DIR Displays a list of files and subdirectories in a directory.
ECHO Displays messages, or turns command echoing on or off.
EXIT Quits the COMMAND.COM program (command interpreter).
MKDIR Creates a directory.
MD Creates a directory.
PATH Displays or sets a search path for executable files.
PAUSE Suspends processing of a batch file and displays a message.
PROMPT Changes the MS-DOS command prompt.
REM Records comments (remarks) in a batch file or config.sys.
RENAME Renames a file or files.
REN Renames a file or files.
RMDIR Removes a directory.
RD Removes a directory.
TIME Displays or sets the system time.
TYPE Displays the contents of a text file.
VER Displays the MS-DOS version.
VOL Displays a disk volume label and serial number.
External Command

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ATTRIB
ATTRIB [d:][path]filename [/S]
ATTRIB [+R|-R] [+A|-A] [+S|-S] [+H|-H] [d:][path]filename [/S]
Sets or displays the read-only, archive, system, and hidden attributes of a file or
directory.
FORMAT
FORMAT a:/[s] [/Q][/U][/V]
Formats a disk to accept DOS files.
DOSKEY
DOSKEY [reinstall] [/bufsize=size][/macros][/history][/insert|/overstrike]
[macroname=[text]]
Loads the Doskey program into memory which can be used to recall DOS
commands so that you can edit them.
BACKUP
Makes a backup copy of one or more files. (In DOS Version 6, this program is
stored on the DOS supplemental disk.)
CHKDSK
CHKDSK [d:][path][filename] [/F][/V]
Checks a disk and provides a file and memory status report.
DELTREEDELTREE [/Y] [d:]path [d:]path[...]
Deletes (erases) a directory including all files and subdirectories that are in it.
EDIT
EDIT [d:][path]filename [/B][/G][/H][/NOHI]
Starts the MS-DOS editor, a text editor used to create and edit ASCII text files.

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LABEL
LABEL [d:][volume label]
Creates or changes or deletes a volume label for a disk.
EXPAND
EXPAND [d:][path]filename [[d:][path]filename[ . . .]]
Expands a compressed file.
What Is Dbms?
As one of the oldest components associated with computers, the database
management system, or DBMS, is a computer software program that is designed
as the means of managing all databases that are currently installed on a system
hard drive or network. Different types of database management systems exist,
with some of them designed for the oversight and proper control of databases that
are configured for specific purposes. Here are some examples of the various
incarnations of DBMS technology that are currently in use, and some of the basic
elements that are part of DBMS software applications.
As the tool that is employed in the broad practice of managing databases, the
DBMS is marketed in many forms. Some of the more popular examples of
DBMS solutions include Microsoft Access, FileMaker, DB2, and Oracle. All
these products provide for the creation of a series of rights or privileges that can
be associated with a specific user. This means that it is possible to designate one
or more database administrators who may control each function, as well as
provide other users with various levels of administration rights. This flexibility
makes the task of using DBMS methods to oversee a system something that can
be centrally controlled, or allocated to several different people.
What is ICT ?
Lets focus on the three words behind ICT:
-INFORMATION -COMMUNICATIONS -TECHNOLOGY
ICT (information and communications technology - or technologies) is an
umbrella term that includes any communication device or application,
encompassing: radio, television, cellular phones, computer and network hardware
and software, satellite systems and so on, as well as the various services and
applications associated with them, such as videoconferencing and distance
learning. ICTs are often spoken of in a particular context, such as ICTs in
education, health care, or libraries.

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A good way to think about ICT is to consider all the uses of digital technology
that already exist to help individuals, businesses and organizations use
information.
What is Linux ?
Pronounced lee-nucks or lih-nucks. A freely-distributable open source operating
system that runs on a number of hardware platforms. The Linux kernel was
developed mainly by Linux Torvalds and it is based on Unix. Because it's free,
and because it runs on many platforms, including PCs and Macintoshes, Linux
has become an extremely popular alternative to proprietary operating systems.
What is Unix ?
Pronounced yoo-niks, a popular multi-user, multitasking operating system
developed at Bell Labs in the early 1970s. Created by just a handful of
programmers, UNIX was designed to be a small, flexible system used exclusively
by programmers.
UNIX was one of the first operating systems to be written in a high-level
programming language, namely C. This meant that it could be installed on
virtually any computer for which a C compiler existed. This natural portability
combined with its low price made it a popular choice among universities.
Action Unix Command DOS Command
MS-DOS Linux / Unix
attrib chmod
backup tar
dir ls
cls clear
copy cp
del rm
deltree rm -R
rmdir
format fdformat / mount / umount
move / rename mv
type less <file>

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cd cd
chdir
more < file more file
md mkdir
What Is Virus ?
A computer virus is usually hard to detect if it's disguised as a harmless file, in
the case of a Trojan horse virus. This type of virus doesn't replicate itself like
most viruses, but instead opens your computer up to malicious imposters.
Leaving you to wonder, how can you tell if you're computer is infected?
Luckily, your computer after coming in contact with a virus or worm will display
some symptoms and signs of infection. It is particularly useful to know the signs
that indicate an infection. Because you can unintentionally introduce a virus to
your computer at anytime when you run an infected program or open an email
attachment. To guard against this you need a good anti-virus program
Signs of a Computer Infection
Some signs that may indicate that your computer is infected include:
• Your computer functions slower than normal
• Your computer responds slowly and freezes often
• Your computer restarts itself often
• You see uncommon error messages, distorted menus, and dialog boxes
• You notice applications on your computer fail to work correctly
• You fail to print correctly
Types of Viruses
But what are the types of computer viruses and worms that you're computer can
come into contact with? The list of viruses is quiet long and complex. So, we
simplified the list by mentioning few broad categories of viruses that can put your
computer and all your personal data on it, in danger. These computer viruses
include:
Computer Viruses
Boot Sector viruses: A boot sector virus infects diskettes and hard drives. All
disks and hard drives contain smaller sections called sectors. The first sector is
called the boot. The boot carries the Mater Boot Record (MBR). MBR functions
to read and load the operating system. So, if a virus infects the boot or MBR of a
disk, such as a floppy disk, your hard drive can become infected, if you re-boot
your computer while the infected disk is in the drive. Once your hard drive is
infected all diskettes that you use in your computer will be infected. Boot sector
viruses often spread to other computers by the use of shared infected disks and
pirated software applications. The best way to disinfect your computer of the boot
sector virus is by using antivirus software.

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Program viruses: A program virus becomes active when the program file
(usually with extensions .BIN, .COM, .EXE, .OVL, .DRV) carrying the virus is
opened. Once active, the virus will make copies of itself and will infect other
programs on the computer.
Multipartite viruses:
Stealth viruses:
Polymorphic viruses:
Macro Viruses:
Trojan Horse Viruses
Blaster
Hardware vs. Software
Software is a general term used to describe a collection of computer programs,
procedures, and documentation that perform some task on a computer system.
Practical computer systems divide software systems into three major classes:
system software, programming software, and application software, although the
distinction is arbitrary and often blurred. Software is an ordered sequence of
instructions for changing the state of the computer hardware in a particular
sequence. It is usually written in high-level programming languages that are
easier and more efficient for humans to use (closer to natural language) than
machine language. High-level languages are compiled or interpreted into machine
language object code. Software may also be written in an assembly language,
essentially, a mnemonic representation of a machine language using a natural
language alphabet.
Hardware is best described as a device that is physically connected to the
computer or something that can be physically touched. A CD-ROM, monitor,
printer, and video card are all examples of computer hardware. Without any
hardware your computer would not exist and software would have nothing to run
on. It is the physical part of a computer, including the digital circuitry, as
distinguished from the computer software that executes within the hardware.
There are several differences between computer hardware and software.
Comparison chart
Improve
this chart
Hardware Software
Types:
Input,storage,processing,control, and output
devices.
System software,
Programming software, and
Application software.
Inter
dependency:
Hardware starts functioning once software is
loaded.
To deliver its set of
instructions, Software is
installed on hardware.
Reliability: Hardware stays at steady reliability level in useful Software needs constant

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Improve
this chart
Hardware Software
life. testing after upgrades.
Failure:
Hardware failure is random. Hardware does have
increasing failure at the last stage.
Software failure is systematic.
Software does not have an
increasing failure rate.
Function:
Hardware serves as the delivery system for
software solutions. The hardware of a computer is
infrequently changed, in comparison with software
and data, which are “soft” in the sense that they are
readily created, modified, or erased on the compute
To perform the specific task
you need to complete.
Software is generally not
needed to for the hardware to
perform its basic level tasks
such as turning on and
responding to input.
Fault: Hardware faults are physical. Software faults are not.
Lifetime: Hardware wears out over time.
Software does not wear out
over time.
Nature: It is physical in nature It is logical in nature
Definition:
Devices required to store and execute (or run) the
software.
Collection of instructions that
enables a user to interact with
the computer. Software is a
program that enables a
computer to perform a specific
task, as opposed to the
physical components of the
system (hardware).
Examples:
CD-ROM, monitor, printer, video card, scanners ,
label makers, routers , and modems.
QuickBooks, Adobe Acrobat,
Internet Explorer , Microsoft
Word , Microsoft Excel
Examples of Computer Hardware
What is computer hardware? What are the different kinds of computer hardware?
For the examples of computer hardware and peripheral devices, read on..
Hardware is the physical aspect of a computer. While computer software exists in
the form of ideas and concepts, computer hardware exists in substance. By
definition, the different parts of a computer that can be touched constitute
computer hardware. Computer hardware includes central processing unit,
motherboard, microchips as well as computer peripherals like input-output and
storage devices that are added to a host computer to enhance its abilities. Here is
an overview of the different kinds of computer hardware.
Computer Hardware Examples
Here is a list of some of the fundamental units of a computer that form the set of
hardware components.
Bus: It is a subsystem that transfers data within and between computers.

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Computer bus provides a logical connection between the different computer
peripherals. A parallel bus is capable of carrying multiple data works in parallel
while a serial bus carries data in a bit-serial form. An internal bus connects the
internal components of a computer to the motherboard while an external bus
connects the external computer peripherals to the motherboard.
• AGP: Short for Accelerated Graphic Port, AGP is a high-speed point-to-
point channel that enables the attachment of a graphics card to the computer's
motherboard.
• Hyper Transport: It is a low-latency point-to-point link that uses high
bandwidth and acts in a bi-directional manner. It facilitates power management.
• PCI: The peripheral component interconnect standard refers to the
computer bus connecting peripheral devices to a motherboard.
• PCI Express: It is a computer expansion card interface format.
• USB: Universal Serial Bus, as it is called, acts as an interface to a host
computer. It enhances the plug-and-play capabilities of a computer. USB is a
popular device used today.
• Quick Path: Also known as the Common System Interface, Quick Path is
a point-to-point processor interconnect that stands in close competition with
Hyper Transport.
• Serial ATA: It is a computer bus that enables the transfer of data between
mass storage devices and the motherboard.
• Serial Attached SCSI: It enables the transfer of data from computer
storage devices like hard drives and tape drives. It is a point-to-point serial
protocol.
Central Processing Unit: It is a set of logic machines that can execute computer
programs. The fundamental function of a CPU is to execute sequences of stored
instructions known as programs. During its first step of operation, the processor
retrieves instructions from the program memory. This step is known as the 'fetch'
step. In the 'decode' step, the processor breaks up the instructions into parts after
which it is executed. During the fourth step of write back, the CPU writes back
the results of the processed instructions into memory.
Computer fan: It is attached to the CPU and is used to lower the temperature of
a computer. There are several fans in the computer case, which help maintain a
constant flow of air to the computer system.
Firmware: It is a computer program that is embedded in a hardware device. It is
midway between hardware and software. Being a piece of computer program, it
is similar to software, while being tightly bound to hardware makes it close to
being a hardware component.
Motherboard: It is the central printed circuit board, abbreviated as PCB, which

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forms the complex electronic system of a computer. A motherboard provides the
computer system with all the electrical connections, the basic circuitry and
components required for its functioning.
Power Supply: This component is responsible for supplying power to the
computer. It converts the AC power from the mains to low voltage DC power for
the internal components of a computer. AT is one of the commonly used power
supplies.
RAM: Short for random access memory, RAM is the physical memory of a
computer. It is used to store the currently running programs and is attached to the
motherboard.
Sound Card: It is a computer expansion card that enables the input and output of
audio signals to and from a computer. Sound cards provide multimedia
applications with the audio components.
Storage Controllers: They are located on the motherboard or on the expansion
cards. Storage controllers include the controllers for the hard disk, CD-ROM and
other drives.
Video Card: Video card that is also known as the graphics card is a hardware
component, which generates and outputs the images to a display.
Media Devices
Devices such as CDs, DVDs and Blue-ray disks are some of the popular
removable storage media that can store digital data. USB flash drives are the
relatively recent storage media that have become a rage today. Tape drives and
zip drives are less commonly used while the floppy disks are obsolete today.
Hard disks and solid-state drives are used for internal storage. Here is a brief
introduction to each of these storage media. Know all about the hard drives.
Blue-ray Disc: It is an optical disc storage media format. It obtains its name from
the blue laser that is used to read and write this type of disc. Owing to its shorter
wavelength, blue-ray discs can store large amounts of data. BD-ROM drive is
used for reading data from a blue-ray disc and a BD writer can be used for both
reading from and writing to a blue-ray disc.
Compact Disc: Popularly known as CDs, compact discs are storage devices for
storing digital data. Standard CDs can store around 80 minutes of audio. CD-
ROMs contain data that is accessible for reading and is not modifiable. CD-
ROMs are used for distribution of computer software and multimedia
applications. A CD Writer is an optical disc drive that uses laser radiation or
electromagnetic waves for reading and writing data onto discs.

54. 54
Digital Versatile Disc: Commonly known as a digital video disk and abbreviated
as DVD, a digital versatile disk is an optical disc storage media. With physical
dimensions similar to those of a compact disc, DVDs can store data as much as
six times more than a CD. A DVD-ROM Drive is used for reading data from a
DVD. A DVD Writer is used for reading and writing data to a DVD. DVD-RAM
Drives allow data to be read and written rapidly from specific types of DVDs.
HD DVD is a high-density optical disc format that succeeded DVD.
Disc Array Controller: It manages physical disc drives and brings them to the
form of logical units. It provides a disk cache and implements hardware RAID.
Floppy Disc: It is a data storage media that is a disk of a thin magnetic storage
medium covered by a plastic shell. With the advent of flash and optical storage
devices, floppy discs have become obsolete.
Hard Disk: It is a non-volatile storage device that stores digital data on magnetic
surfaces. It is used for medium-term storage of data.
Solid-state Drive: This storage device uses solid-state memory to store persistent
data. It can replace the hard disk drive in many applications.
Tape Drive: This data storage device reads and writes data stored on a magnetic
tape. Tape drives have storage capacities ranging from a few megabytes to
multiple gigabytes. They are mainly used for archival storage of data.
USB Flash Drive: It is a small-sized removable and rewritable storage device
with a storage capacity ranging from 64 MB to 64 GB. Due to their high storage
capacity, durability and compact structure, they have gained immense popularity
in the modern times. How does a flash drive work?
Zip Drive: Iomega came up with this medium-capacity storage media in 1994. It
had a capacity of about 100 MB. Zip drives could never become standardized and
were replaced by rewritable CDs.
Networking Hardware Components
Here is an overview of some of those pieces of hardware, which make it possible
for a computer to be a part of a network. Enlighten yourself on computer
networking.
Modem: This device is used for dial-up connections. It modulates analog carrier
signals to encode digital information and demodulates it to decode the
information transmitted.