Computer Fundamentals

Competency-Based Learning Materials

INTRODUCTION TO COMPUTER
CONCEPTS

1

Computer Fundamentals Reviewer

Table of Contents
Computer Fundamentals Reviewer ............................................................................................................................................................ 8
Audience .................................................................................................................................................................................................... 8
Prerequisites .............................................................................................................................................................................................. 8
Computer - Overview ................................................................................................................................................................................. 9
Functionalities of a computer .................................................................................................................................................................. 9
Definition ................................................................................................................................................................................................. 9
Advantages ............................................................................................................................................................................................. 9
HIGH SPEED ...................................................................................................................................................................................... 9
ACCURACY ........................................................................................................................................................................................ 9
STORAGE CAPABILITY ..................................................................................................................................................................... 9
DILIGENCE ....................................................................................................................................................................................... 10
VERSATILITY ................................................................................................................................................................................... 10
RELIABILITY ..................................................................................................................................................................................... 10
AUTOMATION .................................................................................................................................................................................. 10
REDUCTION IN PAPER WORK ....................................................................................................................................................... 10
REDUCTION IN COST ..................................................................................................................................................................... 10
Disadvantages ...................................................................................................................................................................................... 10
NO I.Q ............................................................................................................................................................................................... 10
DEPENDENCY ................................................................................................................................................................................. 10
ENVIRONMENT ................................................................................................................................................................................ 10
NO FEELING .................................................................................................................................................................................... 11
Computer – Applications .......................................................................................................................................................................... 11
Business ............................................................................................................................................................................................... 11
Banking ................................................................................................................................................................................................. 11
Insurance .............................................................................................................................................................................................. 11
Education .............................................................................................................................................................................................. 11
Marketing .............................................................................................................................................................................................. 12
Health Care........................................................................................................................................................................................... 12
Engineering Design .............................................................................................................................................................................. 12
Military .................................................................................................................................................................................................. 13
Communication ..................................................................................................................................................................................... 13
Government Applications ...................................................................................................................................................................... 13
Computer – History Timeline .................................................................................................................................................................... 13
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Computer Fundamentals Reviewer
Computer – Generations .......................................................................................................................................................................... 16
Computer Generations.......................................................................................................................................................................... 16
First Generation .................................................................................................................................................................................... 17
Second Generation ............................................................................................................................................................................... 17
Third Generation ................................................................................................................................................................................... 18
Fourth Generation ................................................................................................................................................................................. 19
Fifth Generation .................................................................................................................................................................................... 19
Computer – Types .................................................................................................................................................................................... 21
PC (Personal Computer) or Desktop .................................................................................................................................................... 21
WorkStation .......................................................................................................................................................................................... 22
Mainframe ............................................................................................................................................................................................. 22
Supercomputer ..................................................................................................................................................................................... 22
2013 TOP 10 SUPERCOMPUTERS ................................................................................................................................................. 23
Computer – Components ......................................................................................................................................................................... 24
Input Unit .............................................................................................................................................................................................. 24
CPU (Central Processing Unit) ............................................................................................................................................................. 24
Output Unit............................................................................................................................................................................................ 24
Computer – CPU ...................................................................................................................................................................................... 25
Memory or Storage Unit: ....................................................................................................................................................................... 25
Control Unit ........................................................................................................................................................................................... 25
ALU (Arithmetic Logic Unit)................................................................................................................................................................... 26
ARITHMETIC SECTION ................................................................................................................................................................... 26
LOGIC SECTION .............................................................................................................................................................................. 26
Computer - Input Devices ......................................................................................................................................................................... 26
Keyboard .............................................................................................................................................................................................. 26
Mouse ................................................................................................................................................................................................... 27
TYPES .............................................................................................................................................................................................. 27
CONNECTIVITY................................................................................................................................................................................ 27
ADVANTAGES .................................................................................................................................................................................. 28
Joystick ................................................................................................................................................................................................. 28
Light Pen............................................................................................................................................................................................... 28
Track Ball .............................................................................................................................................................................................. 28
Scanner ................................................................................................................................................................................................ 28
Digitizer ................................................................................................................................................................................................. 28
Microphone ........................................................................................................................................................................................... 29
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Computer Fundamentals Reviewer
Magnetic Ink Card Reader (MICR) ....................................................................................................................................................... 29
Optical Character Reader (OCR) .......................................................................................................................................................... 29
Bar Code Readers ................................................................................................................................................................................ 29
Optical Mark Reader (OMR) ................................................................................................................................................................. 29
Biometric Input Devices ........................................................................................................................................................................ 30
Computer - Output Devices ...................................................................................................................................................................... 30
Monitors ................................................................................................................................................................................................ 30
Cathode-Ray Tube (CRT) Monitor ........................................................................................................................................................ 30
Flat-Panel Display Monitor .................................................................................................................................................................... 31
Printers ................................................................................................................................................................................................. 31
Impact Printers ...................................................................................................................................................................................... 31
Character Printers: ................................................................................................................................................................................ 31
Dot Matrix Printer .................................................................................................................................................................................. 31
Advantages ....................................................................................................................................................................................... 32
Disadvantages .................................................................................................................................................................................. 32
Daisy Wheel.......................................................................................................................................................................................... 32
Advantages ....................................................................................................................................................................................... 32
Disadvantages .................................................................................................................................................................................. 32
Line Printers.......................................................................................................................................................................................... 32
Drum Printer ......................................................................................................................................................................................... 32
Advantages ....................................................................................................................................................................................... 33
Disadvantages .................................................................................................................................................................................. 33
Non-impact Printers .............................................................................................................................................................................. 33
Laser Printers ....................................................................................................................................................................................... 33
Advantages ....................................................................................................................................................................................... 33
Disadvantage .................................................................................................................................................................................... 33
Inkjet Printers ........................................................................................................................................................................................ 33
Advantages ....................................................................................................................................................................................... 34
Disadvantages .................................................................................................................................................................................. 34
Computer – Memory ................................................................................................................................................................................. 34
Cache Memory ..................................................................................................................................................................................... 34
ADVANTAGE .................................................................................................................................................................................... 34
DISADVANTAGE: ............................................................................................................................................................................. 35
Primary Memory (Main Memory) .......................................................................................................................................................... 35
Secondary Memory ............................................................................................................................................................................... 35
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Computer Fundamentals Reviewer
Removable disk ................................................................................................................................................................................. 35
Internal .............................................................................................................................................................................................. 36
External ............................................................................................................................................................................................. 36
Types of Secondary Storage Devices (rank by capacity, lowest to highest) ......................................................................................... 36
Floppy Disk ....................................................................................................................................................................................... 36
Zip Drive Disks .................................................................................................................................................................................. 36
Compact Disk .................................................................................................................................................................................... 36
DVD................................................................................................................................................................................................... 37
Flash Drive ........................................................................................................................................................................................ 37
Solid State Drive (SSD) ..................................................................................................................................................................... 37
Hard Disk Drive (HDD) ...................................................................................................................................................................... 37
Computer – Memory Characteristics ........................................................................................................................................................ 37
Volatility ................................................................................................................................................................................................ 37
Non-volatile memory ......................................................................................................................................................................... 37
Volatile memory ................................................................................................................................................................................ 37
Mutability............................................................................................................................................................................................... 38
Read/write storage or mutable storage ............................................................................................................................................. 38
Read only storage ............................................................................................................................................................................. 38
Slow write, fast read storage ............................................................................................................................................................. 38
Accessibility .......................................................................................................................................................................................... 38
Random access ................................................................................................................................................................................ 38
Sequential access ............................................................................................................................................................................. 38
Capacity ................................................................................................................................................................................................ 38
Raw capacity ..................................................................................................................................................................................... 38
Computer – RAM...................................................................................................................................................................................... 38
Static RAM (SRAM) .............................................................................................................................................................................. 39
Dynamic RAM (DRAM) ......................................................................................................................................................................... 39
Computer – ROM ..................................................................................................................................................................................... 39
MROM (Masked ROM) ......................................................................................................................................................................... 39
PROM (Programmable Read only Memory) ......................................................................................................................................... 40
EPROM (Erasable and Programmable Read Only Memory) ................................................................................................................ 40
EEPROM (Electrically Erasable and Programmable Read Only Memory) ............................................................................................ 40
Advantages of ROM.............................................................................................................................................................................. 40
Computer – Motherboard ......................................................................................................................................................................... 40
Features................................................................................................................................................................................................ 40
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Computer Fundamentals Reviewer
Popular Manufacturers.......................................................................................................................................................................... 40
Description: ........................................................................................................................................................................................... 41
Computer - Memory Units ........................................................................................................................................................................ 41
Computer – Ports ..................................................................................................................................................................................... 42
What is a Port? ..................................................................................................................................................................................... 42
Characteristics ...................................................................................................................................................................................... 42
Serial Port ............................................................................................................................................................................................. 42
Parallel Port .......................................................................................................................................................................................... 42
PS/2 Port .............................................................................................................................................................................................. 42
Universal Serial Bus (or USB) Port ....................................................................................................................................................... 43
VGA Port............................................................................................................................................................................................... 43
Power Connector .................................................................................................................................................................................. 43
Firewire Port ......................................................................................................................................................................................... 43
Modem .................................................................................................................................................................................................. 43
Ethernet Port......................................................................................................................................................................................... 43
Game Port ............................................................................................................................................................................................ 43
Digital Video Interface, DVI port ............................................................................................................................................................ 43
Sockets ................................................................................................................................................................................................. 44
Computer – Hardware .............................................................................................................................................................................. 44
Relationship between Hardware and Software ..................................................................................................................................... 44
Computer – Software ............................................................................................................................................................................... 44
System Software or Operating System ................................................................................................................................................. 44
Two categories of Operating System ................................................................................................................................................ 45
Types of Operating System ............................................................................................................................................................... 45
Functions of Operating System ......................................................................................................................................................... 45
Examples of Operating System for desktop computers ..................................................................................................................... 46
Example of operating system for Servers.......................................................................................................................................... 46
Application Software ............................................................................................................................................................................. 47
Forms of Application Software .......................................................................................................................................................... 47
Computer - Number System ..................................................................................................................................................................... 48
Decimal Number System ...................................................................................................................................................................... 49
Binary Number System ......................................................................................................................................................................... 49
Characteristics .................................................................................................................................................................................. 49
EXAMPLE ......................................................................................................................................................................................... 49
Octal Number System ........................................................................................................................................................................... 50
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Computer Fundamentals Reviewer
Characteristics .................................................................................................................................................................................. 50
EXAMPLE ......................................................................................................................................................................................... 50
Hexadecimal Number System .............................................................................................................................................................. 50
Characteristics .................................................................................................................................................................................. 50
EXAMPLE ......................................................................................................................................................................................... 50
Computer - Number Conversion ............................................................................................................................................................... 50
Decimal to Other Base System ............................................................................................................................................................. 51
Steps ................................................................................................................................................................................................. 51
EXAMPLE ......................................................................................................................................................................................... 51
Other base system to Decimal System ................................................................................................................................................. 51
Steps ................................................................................................................................................................................................. 51
EXAMPLE ......................................................................................................................................................................................... 51
Other Base System to Non-Decimal System ........................................................................................................................................ 52
Steps ................................................................................................................................................................................................. 52
EXAMPLE ......................................................................................................................................................................................... 52
STEP 1: CONVERT TO DECIMAL.................................................................................................................................................... 52
STEP 2: CONVERT DECIMAL TO BINARY ..................................................................................................................................... 52
Shortcut method - Binary to Octal ......................................................................................................................................................... 53
Steps ................................................................................................................................................................................................. 53
EXAMPLE ......................................................................................................................................................................................... 53
Shortcut method - Octal to Binary ......................................................................................................................................................... 53
Steps ................................................................................................................................................................................................. 53
EXAMPLE ......................................................................................................................................................................................... 53
Shortcut method - Binary to Hexadecimal............................................................................................................................................. 53
Steps ................................................................................................................................................................................................. 53
EXAMPLE ......................................................................................................................................................................................... 53
Shortcut method - Hexadecimal to Binary............................................................................................................................................. 54
Steps ................................................................................................................................................................................................. 54
EXAMPLE ......................................................................................................................................................................................... 54
Computer - Data & information ................................................................................................................................................................. 54
What is Data? ....................................................................................................................................................................................... 54
What is Information? ............................................................................................................................................................................. 55
Data Processing Cycle.......................................................................................................................................................................... 55
Computer – Networking ............................................................................................................................................................................ 56
What is a Computer Network? .............................................................................................................................................................. 56
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Computer Fundamentals Reviewer
Characteristics ...................................................................................................................................................................................... 56
Network Cables .................................................................................................................................................................................... 56
Distributors............................................................................................................................................................................................ 56
Router ................................................................................................................................................................................................... 56
Network Card ........................................................................................................................................................................................ 57
Internal Network Cards ......................................................................................................................................................................... 57
External Network Cards ........................................................................................................................................................................ 57
Computer - Operating System .................................................................................................................................................................. 57
Objectives of Operating System ........................................................................................................................................................... 58
Characteristics of Operating System..................................................................................................................................................... 58
Computer - Internet & Intranet .................................................................................................................................................................. 58
Internet.................................................................................................................................................................................................. 58
Intranet.................................................................................................................................................................................................. 59
Similarities in Internet & Intranet ........................................................................................................................................................... 59
Differences in Internet & Intranet .......................................................................................................................................................... 59

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Computer Fundamentals Reviewer

Computer Fundamentals Reviewer
Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of
set of instructions (called program) and gives the result (output) and saves output for the future use.
This Computer Fundamentals tutorial covers a foundational understanding of computer hardware, software, operating systems,
peripherals etc and how to get the most value and impact from computer technology.

Audience
This tutorial has been prepared for the beginners as well as advanced learners who want to deal with computers. This tutorial is also
very useful for the undergraduate students of computer science, engineering, business administration, management, science,
commerce and arts where an introductory course on computers is a part of curriculum. After completing this tutorial you will find
yourself at a moderate level of expertise in knowledge of Computer basics from where you can take yourself to next levels

Prerequisites
Knowledge of computers is not a prerequisite to follow the contents of this tutorial. This tutorial assumes no background in computers or
computer programming.
Today's world is an information rich world and it has become a necessity for everyone to know about computers. Purpose of this tutorial
is to introduce you about computer systems and its fundamentals.

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Computer - Overview

Computer - Overview
Functionalities of a computer
Any digital computer carries out five functions in gross terms:


Takes data as input.



Stores the data/instructions in its memory and can use them when required.



Process the data and convert it into useful information.



Output the information.



Control all the above four steps.

Definition
Computer System is an electronic data processing device which does the following:


Accept and store an input data.



Process the data input.



And output the processed data in required format.

Advantages
Following list demonstrates the advantages of Computers in today's arena.

HIGH SPEED


Computer is a very fast device.



It is capable of performing addition of very big data.



The computer has units of speed in:



o

Milliseconds

-

one thousandth of a second

(0.0001 sec)

o

Microseconds

-

one millionth of a second

(0.0000001 sec)

o

Nanoseconds

-

one billionth of a second

(0.0000000001 sec)

o

Picoseconds

-

one trillionth of a second

(0.0000000000001 sec)

It can perform millions of calculations in a few seconds as compared to man who can spend many months for doing the same
task.

ACCURACY


In addition to being very fast, computers are very accurate.



The computer has performed calculations 100% error free.



Computers perform all jobs with 100% accuracy.



The computer’s accuracy reflects great precision.



Computations are accurate within a penny, a micron, a picoseconds or whatever level of precisions are required.

STORAGE CAPABILITY


Memory is a very important characteristic of computers.



The computer has much more storage capacity than human beings.
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Computer - Overview


It can store large amount of data.



It can store any type of data such as images, videos, text, audio and any other type.

DILIGENCE


Unlike human beings, a computer is free from monotony, tiredness and lack of concentration.



It can work continuously without creating any error and boredom.



It can do repeated work with same speed and accuracy.

VERSATILITY


A computer is a very versatile machine.



A computer is very flexible in performing the jobs to be done.



This machine can be used to solve the problems relating to various different fields.



At one instant, it may be solving a complex scientific problem and the very next moment it may be playing a card game.

RELIABILITY


A computer is a reliable machine.



The computer can work for unlimited lengths of time with a great accuracy and a little human intervention.



Modern electronic components have failure free long lives.



Computers are designed to make maintenance easy.

AUTOMATION


Computer is an automatic machine.



Automation means ability to perform the task automatically.



Once a program is written and fed into computer, it will accurately execute the program repeatedly without any additional
direction.



Once a program is given to computer i.e stored in computer memory, the program and instruction can control the program
execution without human interaction.

REDUCTION IN PAPER WORK


The use of computers for data processing in an organization leads to reduction in paper work and speeds up the process.



As data in electronic files can be retrieved as and when required, the problem of maintenance of large number of files gets
reduced.

REDUCTION IN COST


Though the initial investment for installing a computer is high but it substantially reduces the cost of each of its transaction.

Disadvantages
Following list demonstrates the disadvantages of Computers in today's arena.

NO I.Q


A computer is a machine and has no intelligence of its own to perform any task.



Each and every instruction has to be given to computer.



A computer cannot take any decision on its own.

DEPENDENCY


It can perform function as instructed by user. So it is fully dependent on human being.

ENVIRONMENT


The operating environment of computer should be dust free and suitable to it.
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Computer – Applications

NO FEELING


Computer has no feeling or emotions.



It cannot make Judgment based on feeling, taste, experience and knowledge unlike a human being.

Computer – Applications
Following list demonstrates the various applications of Computers in today's arena.

Business
The computer's characteristic as high speed of calculation, diligence, accuracy, reliability, or versatility has made it an integrated part in
all business organizations.
Computer used in business organization for:


Payroll Calculations



Budgeting



Sales Analysis



Financial forecasting



Managing employees database



Maintenance of stocks etc.

Banking
Today Banking is almost totally dependent on computer.
Banks provide following facilities:


Banks on-line accounting facility, which include current balances, deposits,
overdrafts, interest charges, shares and trustee records.



ATM machines are making it even easier for customers to deal with banks.

Insurance
Insurance companies are keeping all records up to date with the help of computer. The Insurance Companies, Finance houses and
Stock broking firms are widely using computers for their concerns.
Insurance Companies are maintaining a database of all clients with information showing





how to continue with policies



starting date of the policies



next due installment of a policy



maturity date



interests due



survival benefits

bonus

Education
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Computer – Applications
The computer has provided a lot of facilities in the Education System.


The uses of computer provide a tool in the Education system is known as CBE (Computer Based Education).



CBE involves Control, Delivery and Evaluation of learning.



The computer education is very familiar and rapidly increasing the graph of computer students.



There are number of methods in which educational institutions can use computer to educate the students.



It is used for prepare a database about student performance and analysis are carried out.

Marketing
In Marketing uses of computer are following:


Advertising: With computers, advertising professionals create art and graphics,

write and revise copy, and print and disseminate ads with the goal of selling more products.


At Home Shopping: At home shopping has been made possible through use of

computerized catalogues that provide access to product information and permit direct entry of
orders to be filled by the customers.

Health Care
Computers have become important part in all Medical Systems.
The computers are being used in hospitals to keep the record of patients and
medicines. It is also used in scanning and diagnosing different diseases.
ECG, EEG, Ultrasounds and CT Scans etc. are also done by computerized
machines.
Some of major fields of health care in which computer are used:


Diagnostic System: Computers are used to collect data and
identify cause of illness.



Lab-diagnostic System: All tests can be done and reports are prepared by computer.



Patient Monitoring System: These are used to check patient's signs for abnormality such as in Cardiac Arrest, ECG etc.



Parma Information System: Computer checks Drug-Labels, Expiry dates, harmful drug side effects etc.



Nowadays, computers are also used in performing surgery.

Engineering Design
Computers are widely used in engineering purposes.
One of major areas is CAD (Computer aided design).CAD provides creation, edition, and modification of image. Some fields are:


Structural Engineering: Requires stress and strain analysis required for design

of Ships, Buildings, Budgets, and Airplanes etc.


Industrial Engineering: Computers deals with design, implementation and

improvement of integrated systems of people, materials and equipment.


Architectural Engineering: Computers help in planning towns, designing

buildings, determining a range of buildings on a site using both 2D and 3D drawings.

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Computer – History Timeline

Military
Computers are largely used in defense. Modern tanks, missiles, weapons etc. Employ computerized control systems. Some military
areas where a computer has been used are:



Missile Control



Military Communication



Military operation and planning



Smart Weapons

Communication
Communication means to convey a message, an idea, a picture or speech that
is received and understood clearly and correctly by the person for whom it is
meant. Some main areas in this category are:



E-mail



Chatting



Usenet



FTP



Telnet



Video-conferencing

Government Applications
Computers play an important role in government applications. Some major fields in
this category are:



Computerization of PAN card



Weather Forecasting.



Budgets



Sales tax department



Income tax department



Male/Female ratio



Computerization of voters lists



Computerization of Driving Licensing system

Computer – History Timeline
2000 B.C.

The Abacus is first used for computations. Some claim it originated with the Chinese, but
most scholars argue that it was invented by the Babylonians

1600s

John Napier creates Napiers Bones (multiplication tables on wood or paper) and
logarithms.

1621

William Oughtred invents the slide rule, an early analog computer

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Computer – History Timeline

1642 A.D.

1670

Blaise Pascal creates a mechanical adding machine for tax computations (Pascal’s
Calculator/ Pascaline Calculator). It is unreliable.

Gottfried von Liebniz creates a more reliable adding machine that adds, subtracts, multiplies, divides, and calculates
square roots. He also invented the Binary Arithmetic that became the basis of virtually all modern computers.
Step Reckoner (1671), featured a stepped drum which found use in numerous subsequent
computers.

1842

Charles Babbage (Father of modern computer) designs an analytical engine to perform
general calculations automatically.
The Difference Engine, designed by the English mathematician and inventor Charles
Babbage, was intended to automatically compute mathematical tables which, until that time,
had been tediously calculated by hand and were prone to error. Difference Engine was to be
steam-powered and as large as a locomotive.
The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician
Charles Babbage. It was first described in 1837 as the successor to Babbage's Difference engine, a design for a
mechanical computer. The Analytical Engine incorporated an arithmetic logic unit, control flow in the form of conditional
branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be
described in modern terms as Turing-complete.
Lady Augusta Ada Byron (a.k.a. Lady Lovelace)Countess of lovelace is known as "the first programmer" because she
suggested that a binary system should be used for storage rather than a decimal system for Babbage's designs

1850s

George Boole developed Boolean Logic which would later become significant to the design of computer circuitry and
as a method for refining the searching of information

1890

Herman Hollerith designs a system to record census data (Hollerith’s Tabulating Machine). He was an American

statistician and inventor who developed a mechanical tabulator based on punched cards to rapidly tabulate
statistics from millions of pieces of data. The information is stored as holes in cards, which are interpreted by
machines with electrical sensors. Hollerith starts a company that will eventually become IBM (International Business
Machine).

1939

John Atanasoff, with graduate student Clifford Berry, designs and builds the first electronic digital computer. His
project was funded by a grant for 650$.

1942

ABC (Astanasoff Berry Corporation) was invented by John Astanasoff and Berry Corporation of IOWA state
university. It is the first model of an electronic digital computer. It used vacuum tubes instead of electrical relays in
carrying out computations

1944

Mark 1 was by Howard Aiken with support of IBM. It is the first large scale electromechanical digital computer. It used
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Computer – History Timeline
electrical relays instead of mechanical gears

1946

The giant ENIAC (Electrical Numerical Integrator and Calculator) machine was developed by John W. Mauchly and
J. Presper Eckert, Jr. at the University of Pennsylvania. It used 18,000 vacuum tubes, punch-card input, weighed thirty
tons and occupied a thirty-by-fifty-foot space and cost $500,000 to build. It was only programmable by changing the
wiring, not through software changes, but was productive from 1946 to 1955 and was used to compute artillery firing
tables.

1946

John von Neumann proposes that a program be stored in a computer in the same way that data are stored. His
proposal, called the "von Neumann architecture," is the basis for modern computers.

1947

William Shockley, John Bardeen and Walter Brattain of Bell Labs invented the transistor. In the next decade, vacuum
tubes will be replaced by transistors for which they will receive the Nobel Prize in physics in 1956.

1949

EDSAC (Electronic Delayed Storage Automatic Computer) was an early
British computer. The machine was constructed by Maurice Wilkes and his team
at the University of Cambridge Mathematical Laboratory in England. EDSAC was
the second usefully operational electronic digital stored-program computer.

1951

Eckert and Mauchly build the first general-purpose commercial computer, the UNIVAC (UNIVersal Automatic
Computer). It is the first computer designed and sold commercially, specifically for business data-processing
applications

1952

EDVAC (Electronic Discrete Variable Automatic Calculator) was one of the earliest electronic computers. Unlike its
predecessor the ENIAC, it was binary rather than decimal, and was a stored program computer. It was a binary serial
computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an
ultrasonic serial memory capacity of 1,000 44-bit words (later set to 1,024 words, thus giving a memory, in modern
terms, of 5.5 kilobytes). The EDVAC was built for the U.S. Army's Ballistics Research Laboratory at the Aberdeen
Proving Ground by the University of Pennsylvania's Moore School of Electrical Engineering.

1957

An IBM team, led by John Backus, designs the first successful high-level programming language, FORTRAN (FORmula
TRANslator), for solving engineering and science problems.

1958

The first computer to use the transistor as a switching device, the IBM 7090, is introduced.
Jack St. Clair Kilby and Robert Noycefirst of Texas Instruments manufactured the first integrated circuit, or chip,
which is made up of six components, a feat for which they eventually win a Nobel Prize for physics in the year 2000.
This led to hundreds of tiny transistors that fit on a chip of silicon, then thousands, then millions over the next decade.

1964

The first computer to use integrated circuits, the IBM 360, is announced.

1965

The CTSS (Compatible Time-Sharing System) operating system is introduced. It allows several users simultaneously
to use, or share, a single computer.

1970

A first version of the UNIX operating system is running on the DEC PDP-7.

1971

Nicklaus Wirth designs the Pascal programming language as a language for teaching structured programming
concepts.

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Computer – Generations

1972

Dennis Ritchie of Bell Laboratories in New Jersey develops the language C.

1973

Part of the UNIX operating system is implemented in C.

1975

The first microcomputer, the Altair, is introduced.

1975

The first supercomputer, the Cray-1, is announced.

1976

Digital Equipment Corporation introduces its popular minicomputer, the DEC VAX 11/780.

1977

Steve Wozniak and Steve Jobs found Apple Computer.

1978

Dan Bricklin and Bob Frankston develop the first electronic spreadsheet, called VisiCalc, for the Apple computer.

1979-82

Bjarne Stroustrup of Bell Laboratories in New Jersey introduces "C with Classes."

1981

IBM introduces the IBM PC.

1983-85

C with Classes is redesigned and reimplemented as C++.

1984

Apple introduces the Macintosh, the first widely available computer with a "user-friendly" graphical interface using
icons, windows, and a mouse device.

1988

Work on standardization of C++ begins.

1989

Microsoft Corporation introduces Windows for IBM computers.

1989

The American National Standards Institute (ANSI) publishes the first standard for the C programming language.

Computer – Generations
Computer Generations
Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to
distinguish between varying hardware technologies. But nowadays, generation includes both hardware and software, which together
make up an entire computer system.
There are totally five computer generations known till date. Each generation has been discussed in detail along with their time period,
characteristics. We've used approximate dates against each generation which are normally accepted.
Following are the main five generations of computers
S.N. Generation & Description
1

First Generation
The period of first generation: 1946-1959. Vacuum tube based.

2

Second Generation
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17

Computer – Generations
The period of second generation: 1959-1965. Transistor based.
3

Third Generation
The period of third generation: 1965-1971. Integrated Circuit based.

4

Fourth Generation
The period of fourth generation: 1971-1980. VLSI microprocessor based.

5

Fifth Generation
The period of fifth generation : 1980-onwards.ULSI microprocessor based

First Generation
The period of first generation was 1946-1959.
First generation of computer started with using vacuum tubes as the basic components for
memory and circuitry for CPU (Central Processing Unit). These tubes like electric bulbs
produced a lot of heat and were prone to frequent fusing of the installations, therefore, were
very expensive and could be afforded only by very large organizations.
In this generation mainly batch processing operating system were used. In this generation
Punched cards, Paper tape, Magnetic tape Input & Output device were used.
There were Machine code and electric wired board languages used.
The main features of First Generation are:



Vacuum tube technology



Unreliable



Supported Machine language only



Very costly



Generate lot of heat



Slow Input/output device



Huge size



Need of A.C.



Non portable



Consumed lot of electricity

Some computers of this generation were:



ENIAC (Electronic Numerical Integrator And Computer)



EDVAC (Electronic Discrete Variable Automatic Computer)



UNIVAC (Universal Automatic Computer)



IBM-701 (International Business Machine)



IBM-650

Second Generation
The period of second generation was 1959-1965.
These generations using the transistor were cheaper, consumed less power,
more compact in size, more reliable and faster than the first generation
machines made of vaccum tubes. In this generation, magnetic cores were
used as primary memory and magnetic tape and magnetic disks as
secondary storage devices.
In this generation assembly language and high level programming language
like FORTRAN, COBOL was used.
There was Batch processing and Multiprogramming Operating system used.

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18

Computer – Generations
The main features of Second Generation are:



Use of transistors



Reliable as compared to First generation computers



Smaller size as compared to First generation computers



Generate less heat as compared to First generation computers



Consumed less electricity as compared to First generation computers



Faster than first generation computers



Still very costly



A.C. needed



Support machine and assembly languages

Some computers of this generation were:



IBM 1620



IBM 7094



CDC 1604



CDC 3600



UNIVAC 1108

Third Generation
The period of third generation was 1965-1971.
The third generation of computer is marked by the use of Integrated Circuits
(IC's) in place of transistors. A single I.C has many transistors, resistors and
capacitors along with the associated circuitry. The I.C was invented by Jack
Kilby. This development made computers smaller in size, reliable and
efficient.
In this generation Remote processing, Time-sharing, Real-time, Multiprogramming Operating System were used.
High level language (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC,
ALGOL-68 etc.) were used during this generation.
The main features of Third Generation are:



IC used



More reliable



Smaller size



Generate less heat



Faster



Lesser maintenance



Still costly



A.C needed



Consumed lesser electricity



Support high level language

Some computers of this generation were:



IBM-360 series



Honeywell-6000 series



PDP(Personal Data Processor)



IBM-370/168
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19

Computer – Generations



TDC-316

Fourth Generation
The period of Fourth Generation was 1971-1980.
The fourth generation of computers is marked by the use of Very Large Scale
Integrated (VLSI) circuits. VLSI circuits having about 5000 transistors and other
circuit elements and their associated circuits on a single chip made it possible to
have microcomputers of fourth generation. Fourth Generation computers became
more powerful, compact, reliable, and affordable. As a result, it gave rise to personal
computer (PC) revolution.
In this generation Time sharing, Real time, Networks, Distributed Operating System
were used.
All the Higher level languages like C and C++, DBASE etc. were used in this
generation.

The main features of Fourth Generation are:



VLSI technology used



Very cheap



Portable and reliable



Use of PC's



Very small size



Pipeline processing



No A.C. needed



Concept of internet was introduced



Great developments in the fields of networks



Computers became easily available

Some computers of this generation were:



DEC 10



STAR 1000



PDP 11



CRAY-1(Super Computer)



CRAY-X-MP(Super Computer)

Fifth Generation
The period of Fifth Generation is 1980-till date.
In the fifth generation, the VLSI technology became ULSI (Ultra Large Scale Integration)
technology, resulting in the production of microprocessor chips having ten million
electronic components.
This generation is based on parallel processing hardware and AI (Artificial Intelligence)
software.
AI is an emerging branch in computer science, which interprets means and method of
making computers think like human beings.
All the Higher level languages like C and C++, Java, .Net etc. are used in this generation.
AI includes:
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20

Computer – Generations



Robotics



Neural networks



Game Playing



Development of expert systems to make decisions in real life situations.



Natural language understanding and generation.

The main features of Fifth Generation are:



ULSI technology



Development of true artificial intelligence



Development of Natural language processing



Advancement in Parallel Processing



Advancement in Superconductor technology



More user friendly interfaces with multimedia features



Availability of very powerful and compact computers at cheaper rates

Some computer types of this generation are:



Desktop



Laptop



Notebook



Ultra Book



Chrome Book

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21

Computer – Types

Computer – Types
Computer can be broadly classified by their speed and computing power.
Sr. No.

1

Type

Desktop Computer

Specifications





2

3

WorkStation






Single user computer system.
Similar to Personal Computer or Desktop but have more powerful microprocessor.
High-powered business computers.
They are designed for specialized, high-end applications like engineering programs
such as CAD (Computer Aided Design).





These are computers that can be carried easily
Laptop computer is a small, light weight PC about size of the three-ring notebook
Notebooks and subnotebook computers that offer similar computing power but
are smaller in size than a laptop.
Tablet PCs are portable lightweight computers that allow users to roam the office,
home, or factory floor carrying the device like clipboard.

Portable Computers




3

Server







4

Main Frame





5

Single user computer system.
Moderately powerful microprocessor.
Commonly used to run applications such as word processing, spreadsheets and
networked applications such as email and web browsing.
They are small enough to fit on an office desk

Supercomputer


Servers are high performance computers used in businesses and other
organizations.
Servers provide services to many end users or clients.
Server hardware is optimized for quick response time to multiple network requests.
Servers have multiple Central Processing Units (CPUs), large amounts of Random
Access Memory (RAM) and multiple high capacity disk drives that provide very fast
information retrieval.
It is used to handle internet traffic and communications.
Multi-user computer system. Capable of supporting hundreds of users
simultaneously.
Large and powerful computer shared by dozens or even hundreds of concurrent
users connected to the machine over network.
This is the most powerful computer systems, with the fastest processing speeds.
Designed for applications that requires extensive and rapid computational
activities.
An extremely fast computer which can perform hundreds of millions of instructions
per second.

PC (Personal Computer) or Desktop
A PC can be defined as a small, relatively inexpensive computer designed for an
individual user. PCs are based on the microprocessor technology that enables
manufacturers to put an entire CPU on one chip. Businesses use personal computers for
word processing, accounting, desktop publishing, and for running spreadsheet and
database management applications. At home, the most popular use for personal
computers is for playing games and surfing the Internet.
Although personal computers are designed as single-user systems, these systems are normally linked together to form a network. In
terms of power, now-a-days High-end models of the Macintosh and PC offer the same computing power and graphics capability as lowend workstations by Sun Microsystems, Hewlett-Packard, and DELL.

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22

Computer – Types

WorkStation
Workstation is a computer used for engineering applications (CAD/CAM), desktop
publishing, software development, and other such types of applications which
require a moderate amount of computing power and relatively high quality graphics
capabilities.
Workstations generally come with a large, high-resolution graphics screen, large
amount of RAM, inbuilt network support, and a graphical user interface. Most
workstations also have a mass storage device such as a disk drive, but a special
type of workstation, called a diskless workstation, comes without a disk drive.
Common operating systems for workstations are UNIX and Windows NT. Like PC,
Workstations are also single-user computers. However, workstations are typically
linked together to form a local-area network, although they can also be used as stand-alone systems.

Mainframe
Mainframe is a very large in size and is an expensive computer capable of supporting hundreds, or even thousands, of users
simultaneously. Mainframe executes many programs concurrently. Mainframes support many simultaneous programs execution.

Supercomputer
Supercomputers are one of the fastest computers currently available. Supercomputers are very expensive and are employed for
specialized applications that require immense amounts of mathematical calculations (number crunching). For example, weather
forecasting , scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and
analysis of geological data (e.g. in petrochemical prospecting).

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23

Computer – Types

2013 TOP 10 SUPERCOMPUTERS
Site / Country

OS

Number of
cores

Clock
Speed /
Core

Power
(kW)

1

Tianhe-2
(MilkyWay-2)

National University
of Defense
Technology
China

LINUX

3,120,000

2.20 GHz

17,808

2

Titan

Oak Ridge National
Laboratory
United States

LINUX

560,640

2.20 GHz

8,209

Sequoia

Lawrence
Livermore National
Laboratory
United States

LINUX

1,572,864

1.60 GHz

7,890

4

K
Supercomputer

RIKEN Advanced
Institute for
Computational
Science (AICS)
Japan

LINUX

705,024

2.00 GHz

12,660

5

Mira

Argonne National
Laboratory
United States

LINUX

786,432

1.60 GHz

3,945

6

Stampede

Texas Advanced
Computing
Center/Univ. of
Texas
United States

LINUX

462,462

2.70 GHz

4,510

7

JUQUEEN

Forschungszentrum
Juelich (FZJ)
Germany

LINUX

458,752

1.60 GHz

2,301

8

Vulcan

Lawrence
Livermore National
Laboratory United
States

LINUX

393,216

1.60 GHz

1,972

9

SuperMUC

Leibniz
Rechenzentrum
Germany

LINUX

147,456

2.70 GHz

3,423

Tianhe-1A

National
Supercomputing
Center in Tianjin
China

LINUX

186,368

2.93 GHz

4,040

Rank

3

10

System

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24

Computer – Components

Computer – Components
All types of computer follows a same basic logical structure and perform the following five basic operations for converting raw input data
into information useful to their users
Sr. No.

Operation

Description

1

Take Input

The process of entering data and instructions into the computer system.

2

Store Data

Saving data and instructions so that they are available for processing as and when required.

3

Processing Data

Performing arithmetic, logical operations on data in order to convert them into useful
information.

4

Output Information

The process of producing useful information or results for the user, such as a printed report
or visual display.

5

Control the workflow

Direct the manner and sequence in which all of the above operations are performed.

Input Unit
This unit contains devices with the help of which we enter data into computer. This unit makes link between user and computer.
The input devices translate the human being information into the form understandable by computer.

CPU (Central Processing Unit)
CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate
results and instructions (program).It controls the operation of all parts of computer.
CPU itself has following three components



ALU(Arithmetic Logic Unit)



Memory Unit



Control Unit

Output Unit
Output unit consists of devices with the help of which we get the information from computer. This unit is a link between computer and
users.
Output devices translate the computer's output into the form understandable by users.

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Computer – CPU

Computer – CPU


CPU is considered as the brain of the computer.



CPU performs all types of data processing operations.



It stores data, intermediate result and instructions (program).



It controls the operation of all parts of computer.

CPU itself has following three components.



Memory Or Storage Unit:



Control Unit



ALU(Arithmetic Logic Unit)

Memory or Storage Unit:
This unit can store instruction, data and intermediate results. This unit supplies information to the other units of the computer when
needed. It is also known as internal storage unit or main memory or primary storage or Random access memory (RAM).
Its size affects speed, power and capability. There are primary memory and secondary memory two types of memories in the computer.
Functions of Memory Unit are:



It stores all the data to be processed and the instructions required for processing.



It stores intermediate results of processing.



It stores final results of processing before these results are released to an output device.



All inputs and outputs are transmitted through main memory.

Control Unit
This unit controls the operations of all parts of computer. It does not carry out any actual data processing operations.
Functions of this unit are



It is responsible for controlling the transfer of data and instructions among other units of a computer.



It manages and coordinates all the units of the computer.



It obtains the instructions from the memory, interprets them and directs the operation of the computer.



It communicates with Input/Output devices for transfer of data or results from storage.



It does not process or store data.
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26

Computer - Input Devices

ALU (Arithmetic Logic Unit)
This unit consists of two subsections namely



Arithmetic section



Logic Section

ARITHMETIC SECTION
Function of Arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication and division. All complex
operations are done by making repetitive use of above operations.

LOGIC SECTION
Function of logic section is to perform logic operations such as comparing, selecting, matching and merging of data.

Computer - Input Devices
Following are few of the important input devices which are used in Computer Systems



Keyboard



Mouse



Joy Stick



Light pen



Track Ball



Scanner



Graphic Tablet



Microphone



Magnetic Ink Card Reader(MICR)



Optical Character Reader(OCR)



Bar Code Reader



Optical Mark Reader

Keyboard
Most common and very popular input device is keyboard. The keyboard helps in inputting the data to the computer. The layout of the
keyboard is like that of traditional typewriter, although there are some additional keys provided for performing some additional functions.
Keyboards are of two sizes 84 keys or 101/102 keys, but now 104 keys or 108 keys keyboard is also available for Windows and
Internet.
The keys are following
Sr. No.

Keys

Description

1

Typing Keys

These keys include the letter keys (A-Z) and digits keys (0-9) which are generally give same layout as that
of typewriters.

2

Numeric
Keypad

It is used to enter numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid
out in the same configuration used by most adding machine and calculators.

3

Function Keys

The twelve (12) functions keys are present on the keyboard. These are arranged in a row along the top of
the keyboard. Each function key has unique meaning and is used for some specific purpose.

4

Control keys

These keys provides cursor and screen control. It includes four directional arrow key. Control keys also
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27

Computer - Input Devices
include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).
Special
Purpose Keys

5

Keyboard also contains some special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Space bar,
Tab, and Print Screen.

The following are the different keyboard layout:
Sr. No.

Layout

Description

1

QWERTY

Invented Christopher Sholes.

2

QWERTZ

Widely used in Germany and much of Central Europe.

3

AZERTY

Used in France, Belgium and some neighboring countries.

Mouse
Mouse is most popular Pointing device. It is a very famous cursor-control
device. It is a small palm size box with a round ball at its base which senses
the movement of mouse and sends corresponding signals to CPU on
pressing the buttons.
Generally it has two buttons called left and right button and scroll bar is
present at the mid. Mouse can be used to control the position of cursor on
screen, but it cannot be used to enter text into the computer.

TYPES


Mechanical mouse – has a rubber or metal ball on its underside.



Optical and laser mouse – uses devices that emit and sense light to detect the mouse movements.



Inertial and gyroscopic mice - Often called "air mice" since they do not require a surface to operate,



3D mice - Also known as bats, flying mice, or wands, these devices generally function through ultrasound and provide at least
three degrees of freedom.



Ergonomic mouse - type of mouse intended to provide optimum comfort and avoid injuries.

CONNECTIVITY


Serial interface and protocol



PS/2 interface and protocol



USB



Cordless or wireless
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28

Computer - Input Devices

ADVANTAGES


Easy to use



Not very expensive



Moves the cursor faster than the arrow keys of keyboard.

Joystick
Joystick is also a pointing device which is used to move cursor position on a monitor screen. It is
a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves
in a socket. The Joystick can be moved in all four directions.
The function of joystick is similar to that of a mouse. It is mainly used in Computer Aided
Designing (CAD) and playing computer games.

Light Pen
Light pen is a pointing device which is similar to a pen. It is used to select a displayed
menu item or draw pictures on the monitor screen. It consists of a photocell and an optical
system placed in a small tube.
When light pen's tip is moved over the monitor screen and pen button is pressed, its
photocell sensing element detects the screen location and sends the corresponding signal
to the CPU.

Track Ball
Track ball is an input device that is mostly used in notebook or laptop computer,
instead of a mouse. This is a ball which is half inserted and by moving fingers on ball,
pointer can be moved.
Since the whole device is not moved, a track ball requires less space than a mouse.
A track ball comes in various shapes like a ball, a button and a square.

Scanner
Scanner is an input device which works more like a photocopy machine. It is used when some
information is available on a paper and it is to be transferred to the hard disc of the computer for
further manipulation.
Scanner captures images from the source which are then converted into the digital form that can be
stored on the disc. These images can be edited before they are printed.

Digitizer
Digitizer is an input device which converts analog information into a digital form. Digitizer can
convert a signal from the television camera into a series of numbers that could be stored in a
computer. They can be used by the computer to create a picture of whatever the camera
had been pointed at.

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Computer - Input Devices
Digitizer is also known as Tablet or Graphics Tablet because it converts graphics and pictorial data into binary inputs. A graphic tablet
as digitizer is used for doing fine works of drawing and images manipulation applications.

Microphone
Microphone is an input device to input sound that is then stored in digital form. The microphone is used
for various applications like adding sound to a multimedia presentation or for mixing music.

Magnetic Ink Card Reader (MICR)
MICR input device is generally used in banks because of a large number of cheese to be processed
every day. The bank's code number and cheque number are printed on the cheques with a special type
of ink that contains particles of magnetic material that are machine readable.
This reading process is called Magnetic Ink Character Recognition (MICR). The main advantages of
MICR are that it is fast and less error prone.

Optical Character Reader (OCR)
OCR is an input device used to read a printed text. OCR scans text optically character by character,
converts them into a machine readable code and stores the text on the system memory.

Bar Code Readers
Bar Code Reader is a device used for reading bar coded data (data in form of light and
dark lines). Bar coded data is generally used in labeling goods, numbering the books etc. It
may be a hand held scanner or may be embedded in a stationary scanner.
Bar Code Reader scans a bar code image, converts it into an alphanumeric value which is
then fed to the computer to which bar code reader is connected.

Optical Mark Reader (OMR)
OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few
alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice
questions.

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Computer - Output Devices

Biometric Input Devices
It is the technology of authenticating a person’s identity by verifying a personal characteristic. Biometric devices grant users access to
programs, systems, or rooms by analyzing some biometric identifier.
Example of personal identity measured by biometric input device


Fingerprints



Hand Geometry



Facial Features



Voice



Signature



Eye Pattern

Computer - Output Devices
Following are few of the important output devices which are used in Computer Systems



Monitors



Graphic Plotter



Printer

Monitors
Monitor commonly called as Visual Display Unit (VDU) is the main output device of a computer. It forms images from tiny dots, called
pixels that are arranged in a rectangular form. The sharpness of the image depends upon the no. of the pixels.
Monitors are defined in terms of the following:


Graphical Adapter - it is the electronic linked between the motherboard and the monitor.



Size – It refers to the diagonal dimension of the display screen. It ranges from 5 to 30 inches.



Resolution – refers to the number of addressable points on the screen – the number of light can be directed under the
program control. These points is sometimes called PIXELS (short for picture elements)



Color – either monochrome or colored
o

Monochrome – displays images in a single color, usually white, green, blue, red or amber.

o

Color Monitors – mix red, green and blue to achieve a spectrum of colors and are called RGB monitors.

There are two kinds of viewing screen used for monitors.



Cathode-Ray Tube (CRT)



Flat- Panel Display

Cathode-Ray Tube (CRT) Monitor
In the CRT display is made up of small picture elements called pixels for short. The
smaller the pixels, the better the image clarity, or resolution. It takes more than one
illuminated pixel to form whole character, such as the letter e in the word help.
A finite number of characters can be displayed on a screen at once. The screen can be
divided into a series of character boxes - fixed location on the screen where a standard
character can be placed.
The most screens are capable of displaying 80 characters of data horizontally and 25
lines vertically. There are some disadvantages of CRT



Large in Size
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Computer - Output Devices



High Power consumption

Flat-Panel Display Monitor
The flat-panel display refers to a class of video devices that have reduced volume,
weight and power requirement compare to the CRT. You can hang them on walls or
wear them on your wrists. Current uses for flat-panel displays include calculators,
videogames, monitors, laptop computer, graphics display.
The flat-panel display are divided into two categories



Emissive Displays - The emissive displays are devices that convert electrical
energy into light. Examples are plasma panel and LED (Light-Emitting Diodes).



Non-Emissive Displays - The Non-emissive displays use optical effects to
convert sunlight or light from some other source into graphics patterns. Example is LCD(Liquid-Crystal Device)

Printers
Printer is the most important output device, which is used to print information on paper.
There are two types of printers



Impact Printers



Non-Impact Printers

Impact Printers
The printers that print the characters by striking against the ribbon and onto the paper are called impact printers.
Characteristics of Impact Printers are following



Very low consumable costs



Impact printers are very noisy



Useful for bulk printing due to low cost



There is physical contact with the paper to produce an image



These printers are of two types



Character printers



Line printers

Character Printers:
Character Printers are printers which print one character at a time.
These are of further two types



Dot Matrix Printer(DMP)



Daisy Wheel

Dot Matrix Printer
In the market one of the most popular printer is Dot Matrix Printer because of their ease of
printing features and economical price. Each character printed is in form of pattern of Dot's
and head consists of a Matrix of Pins of size(5*7, 7*9, 9*7 or 9*9) which comes out to form
a character that is why it is called Dot Matrix Printer.

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Computer - Output Devices

ADVANTAGES


Inexpensive



Widely Used



Other language characters can be printed

DISADVANTAGES


Slow Speed



Poor Quality

Daisy Wheel
Head is lying on a wheel and Pins corresponding to characters are like petals of Daisy (flower
name) that is why it is called Daisy Wheel Printer. These printers are generally used for wordprocessing in offices which require a few letters to be sent here and there with very nice quality
representation.

ADVANTAGES


More reliable than DMP's



Better quality



The fonts of character can be easily changed.

DISADVANTAGES


Slower than DMP's



Noisy



More expensive than DMP's

Line Printers
Line printers are printers which print one line at a time.

These are of further two types



Drum Printer



Chain Printer

Drum Printer
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Computer - Output Devices
This printer is like a drum in shape so it called drum printer. The surface of drum is
divided into number of tracks. Total tracks are equal to size of paper i.e for a paper
width of 132 characters, Drum will have 132 tracks. A character set is embossed on
track. The different characters sets are available in market 48 character set, 64 and 96
characters set. One rotation of drum prints one line. Drum Printers are fast in speed
and speed in between 300 to 2000 lines per minute.

ADVANTAGES


Very high speed

DISADVANTAGES


Very expensive



Characters fonts cannot be changed

Non-impact Printers
The printers that print the characters without striking against the ribbon and onto the paper are called Non-impact Printers. These
printers print a complete page at a time, also called as Page Printers.
The quality of output from a non-impact printer is normally excellent and much better than the output of impact printers.
These printers are of two types



Laser Printers



Inkjet Printers

Characteristics of Non-impact Printers



Faster than impact printers.



They are not noisy.



High quality.



Support many fonts and different character size.

Laser Printers
These are non-impact page printers. They use laser lights to produces the dots
needed to form the characters to be printed on a page.

ADVANTAGES


Very high speed.



Very high quality output.



Give good graphics quality.



Support many fonts and different character size.

DISADVANTAGE


Expensive.



Cannot be used to produce multiple copies of a document in a single printing.

Inkjet Printers

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Computer – Memory
Inkjet printers are non-impact character printers based on a relatively new technology. They print characters by spraying small drops of
ink onto paper. Inkjet printers produce high quality output with presentable features.
They make less noise because no hammering is done and these have many styles of
printing modes available. Color printing is also possible. Some models of Inkjet printers
can produce multiple copies of printing also.

ADVANTAGES


High quality printing



More reliable

DISADVANTAGES


Expensive as cost per page is high



Slow as compare to laser printer

Computer – Memory
A memory is just like a human brain. It is used to store data and instruction. Computer memory is the storage space in computer where
data is to be processed and instructions required for processing are stored.
Alternatively referred to as storage, storage media, or storage medium, a storage device is a hardware device capable of holding
information.
The memory is divided into large number of small parts. Each part is called Cell. Each location or cell has a unique address which
varies from zero to memory size minus one.
For example if computer has 64k words, then this memory unit has 64 * 1024=65536 memory location. The address of these locations
varies from 0 to 65535.
Memory is primarily of three types



Cache Memory



Primary Memory/Main Memory



Secondary Memory

Cache Memory
Cache memory is a very high speed semiconductor memory which can speed up CPU. It acts
as a buffer between the CPU and main memory.
It is used to hold those parts of data and program which are most frequently used by CPU.
The parts of data and programs are transferred from disk to cache memory by operating
system, from where CPU can access them.

ADVANTAGE


Cache memory is faster than main memory.



It consumes less access time as compared to main memory.



It stores the program that can be executed within a short period of time.



It stores data for temporary use.

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Computer – Memory

DISADVANTAGE:


Cache memory has limited capacity.



It is very expensive.

Primary Memory (Main Memory)
Primary memory holds only those data and instructions on which computer is currently working. It
has limited capacity and data get lost when power is switched off.
It is generally made up of semiconductor device. These memories are not as fast as registers. The
data and instruction required to be processed earlier reside in main memory. It is divided into two
subcategories RAM and ROM.
Characteristic of Main Memory



These are semiconductor memories.



It known as main memory.



Usually volatile memory.



Data is lost in case power is switch off.



It is working memory of the computer.



Faster than secondary memories.



A computer cannot run without primary memory.

Secondary Memory
This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing
Data/Information permanently.
CPU directly does not access these memories instead they are accessed via input-output
routines. Contents of secondary memories are first transferred to main memory, and then
CPU can access it. For example: disk, CD-ROM, DVD etc.
Characteristic of Secondary Memory



These are magnetic and optical memories.



It is known as backup memory.



It is non-volatile memory.



Data is permanently stored even if power is switched off.



It is used for storage of the data in the computer.



Computer may run without secondary memory.



Slower than primary memories.



The secondary memory could be a removable, internal, or external storage.

REMOVABLE DISK
Alternatively referred to as removable storage and removable media, a removable disk is a media that enables a user to move d ata
between computers without having to open their computer. Below is a listing of the removable disks you're likely to use with your
computer.


Floppy diskettes



CD disc, DVD disc, Blu-ray disc



Tape drive cartridges



Thumb drives. Flash drives

Although hard drives that connect to a computers USB port do allow you to move data between computers without opening the
computer these drives are referred to as an external drive and not a removable disk drive.
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Computer – Memory

INTERNAL
Internal is a term used to describe a device that is installed within the computer. For example, a video card is an internal device and a
printer is an external device. When referring to a drive an internal drive such as an internal hard drive is any drive that is inside the
computer.

EXTERNAL
External describes a hardware device that is installed outside of the computer.

Types of Secondary Storage Devices (rank by capacity, lowest to
highest)
RANK

DEVICE

CAPACITY

1

Floppy Disk

1.44MB to 4MB

2

Zip Drive Disks

100MB, 250MB and 750MB

3

Compact Disc (CD)

650MB to 700MB (74-80 minutes)

4

Digital Versatile Disc (DVD)

DVD-5 4.7GB (2 hours)
DVD-9 8.54GB (4 hours)
DVD-10 9.4GB (4.5 hours)
DVD-18 17.08GB (8 hours)
Blu-Ray DVD 25-50GB
HD-DVD 15-30GB

5

Jump Drive

1GB to 32 GB

6

Solid State Drive (SDD)

500GB

7

Hard Disk Drive (HDD)

1GB to 4TB

FLOPPY DISK
A floppy disk, or diskette, is a disk storage medium composed of a disk of thin and flexible
magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes
dust particles. They are read and written by a floppy disk drive (FDD).
Floppy disks, initially as 8-inch (200 mm) media and later in 5.25-inch (133 mm) and 3.5-inch (90
mm) sizes, were a ubiquitous form of data storage and exchange from the mid-1970s well into the
first decade of the 21st century.[1]
Today, because of the limited capacity and reliability of floppy diskettes many computers no
longer come equipped with floppy disk drives and are being replaced with CD-R, other writable discs, and flash drives.

ZIP DRIVE DISKS
Is a medium-capacity removable disk storage system, introduced by Iomega in late 1994, Zip disk had a capacity of 100MB but later
versions increased to 250 and then 750MB.

COMPACT DISK
Abbreviated as CD, a compact disc is a flat, round storage medium that is read by a laser in a CD-ROM
drive that was invented by James Russell and first created at a Philips factory in Germany on August 17,
1982. The standard CD is capable of holding 72 minutes of music or 650 MB of data. 80 minute CDs are
also commonly used to store data and are capable of containing 700 MB of data. In the picture to the right,
is an example of what the standard compact disc looks like.

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Computer – Memory Characteristics

DVD

DVD is a digital optical disc storage format, invented and developed by Philips, Sony,
Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than compact discs
while having the same dimensions.

FLASH DRIVE
Alternatively referred to as a USB drive, data stick, pen drive, keychain drive and thumb drive, a jump
drive is a portable drive that is often the size of your thumb that connects to the computer USB port.
Today, flash drives are available in sizes such as 256MB, 512MB, 1GB, 5GB, 8GB, 16GB, 32GB and
are an easy way to transfer and store information.
Unlike a hard drive the flash drive only contains an integrated circuit memory board capable of storing
information and has no movable parts.

SOLID STATE DRIVE (SSD)
Also known as Solid-State Disk, SSD is a drive that uses non-volatile memory as a means of storing
and accessing data, much like computer RAM. Unlike other storage devices such as hard drives, an
SSD has no moving parts, which gives it advantages such as accessing stored information faster,
produces no noise, often more reliable, and consume much less power than the traditional hard drive
found in computers.

HARD DISK DRIVE (HDD)
Alternatively referred to as a hard disk drive and abbreviated as HD or
HDD, the hard drive is the computer's main storage media device that
permanently stores all data on the computer. The hard drive was first
introduced on September 13, 1956 and consists of one or more hard drive
platters inside of air sealed casing. Most computer hard drives are in an
internal drive bay at the front of the computer and connect to the
motherboard using either ATA, SCSI, or a SATA cable and power cable.
Below, is a picture of what the inside of a hard drive looks like for a
desktop and laptop hard drive.

Computer – Memory Characteristics
Storage technologies at all levels of the storage hierarchy can be differentiated by evaluating certain core characteristics as well as
measuring characteristics specific to a particular implementation. These core characteristics are volatility, mutability and accessibility.
For any particular implementation of any storage technology, the characteristics worth measuring are capacity and performance.

Volatility
NON-VOLATILE MEMORY
A memory (data storage) can retain the stored information even if it is not constantly supplied with electric power. It is suitable for longterm storage of information.

VOLATILE MEMORY
A memory requires constant power to maintain the stored information. The fastest memory technologies of today are volatile ones (not
a universal rule). Since primary storage is required to be very fast, it predominantly uses volatile memory.
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Computer – RAM
An Uninterruptible Power Supply (UPS) can be used to give a computer a brief window of time to move information from primary
volatile storage into non-volatile storage before the batteries are exhausted. Some systems have integrated batteries that maintain
volatile storage for several hours.

Mutability
READ/WRITE STORAGE OR MUTABLE STORAGE
It allows information to be overwritten at any time. A computer without some amount of read/write storage for primary storage purposes
would be useless for many tasks. Modern computers typically use read/write storage also for secondary storage.

READ ONLY STORAGE
Retains the information stored at the time of manufacture, and write once storage (Write Once Read Many) allows the information to be
written only once at some point after manufacture. These are called Immutable Storage. Immutable storage is used for tertiary and offline storage. Examples include CD-ROM, CD-R and DVD-R.

SLOW WRITE, FAST READ STORAGE
Read/write storage which allows information to be overwritten multiple times, but with the write operation being much slower than the
read operation. Examples include CD-RW, DVD-RW and flash memory.

Accessibility
RANDOM ACCESS
Any location in storage can be accessed at any moment in approximately the same amount of time. Such characteristic is well suited
for primary and secondary storage. Most semiconductor memories and disk drives provide random access.

SEQUENTIAL ACCESS
The accessing of pieces of information will be in a serial order, one after the other; therefore the time to access a particular piece of
information depends upon which piece of information was last accessed. Such characteristic is typical of off-line storage.

Capacity
RAW CAPACITY
It is the total amount of stored information that a storage device or medium can hold. It is expressed as a quantity of bits or bytes (e.g.
10.4 megabytes).

Computer – RAM
A RAM constitutes the internal memory of the CPU for storing data, program and program result. It
is read/write memory. It is called random access memory (RAM).
Since access time in RAM is independent of the address to the word that is, each storage location
inside the memory is as easy to reach as other location & takes the same amount of time. We can
reach into the memory at random & extremely fast but can also be quite expensive.
RAM is volatile, i.e. data stored in it is lost when we switch off the computer or if there is a power
failure. Hence a backup uninterruptible power system (UPS) is often used with computers. RAM is
small, both in terms of its physical size and in the amount of data it can hold.

RAM is of two types



Static RAM (SRAM)



Dynamic RAM (DRAM)

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Computer – ROM

Static RAM (SRAM)
The word static indicates that the memory retains its contents as long as power remains applied. However, data is lost when the power
gets down due to volatile nature. SRAM chips use a matrix of 6-transistors and no capacitors. Transistors do not require power to
prevent leakage, so SRAM need not have to be refreshed on a regular basis.
Because of the extra space in the matrix, SRAM uses more chips than DRAM for the same amount of storage space, thus making the
manufacturing costs higher.
Static RAM is used as cache memory needs to be very fast and small.
Characteristic of the Static RAM



It has long data lifetime



There is no need to refresh



Faster



Used as cache memory



Large size



Expensive



High power consumption

Dynamic RAM (DRAM)
DRAM, unlike SRAM, must be continually refreshed in order for it to maintain the data. This is done by placing the memory on a
refresh circuit that rewrites the data several hundred times per second. DRAM is used for most system memory because it is cheap and
small. All DRAMs are made up of memory cells. These cells are composed of one capacitor and one transistor.
Characteristic of the Dynamic RAM



It has short data lifetime



Need to refresh continuously



Slower as compared to SRAM



Used as RAM



lesser in size



Less expensive



Less power consumption

Computer – ROM
ROM stands for Read Only Memory. The memory from which we can only read but cannot
write on it. This type of memory is non-volatile. The information is stored permanently in such
memories during manufacture.
A ROM, stores such instruction as are required to start computer when electricity is first
turned on, this operation is referred to as bootstrap. ROM chip are not only used in the
computer but also in other electronic items like washing machine and microwave oven.

Following are the various types of ROM

MROM (Masked ROM)
The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are
known as masked ROMs. It is inexpensive ROM.

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Computer – Motherboard

PROM (Programmable Read only Memory)
PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents
using a PROM programmer. Inside the PROM chip there are small fuses which are burnt open during programming. It can be
programmed only once and is not erasable.

EPROM (Erasable and Programmable Read Only Memory)
The EPROM can be erased by exposing it to ultra-violet light for duration of up to 40 minutes. Usually, an EPROM eraser achieves this
function. During programming an electrical charge is trapped in an insulated gate region. The charge is retained for more than ten years
because the charge has no leakage path. For erasing this charge, ultra-violet light is passed through a quartz crystal window (lid). This
exposure to ultra-violet light dissipates the charge. During normal use the quartz lid is sealed with a sticker.

EEPROM (Electrically Erasable and Programmable Read Only
Memory)
The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and
programming take about 4 to 10 ms (milli second). In EEPROM, any location can be selectively erased and programmed. EEPROMs
can be erased one byte at a time, rather than erasing the entire chip. Hence, the process of re-programming is flexible but slow.

Advantages of ROM


Non-volatile in nature



These cannot be accidentally changed



Cheaper than RAMs



Easy to test



More Reliable than RAMs



These are static and do not require refreshing



Its contents are always known and can be verified

Computer – Motherboard
The motherboard serves as a single platform to connect all of the parts of a computer
together. A motherboard connects CPU, memory, hard drives, optical drives, video card,
sound card and other ports and expansion cards directly or via cables. It can be considered
as the backbone of a computer.

Features


Motherboard varies greatly in supporting various types of components.



Normally a motherboard supports a single type of CPU and few types of memories.



Video Cards, Hard disks, Sound Cards have to compatible with motherboard to function properly.



Motherboards, cases and power supplies must be compatible to work properly together.

Popular Manufacturers


Intel



ASUS



AOpen



ABIT



Biostar
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Computer - Memory Units



Gigabyte



MSI

Description:
The motherboard is mounted inside the case and is securely attached via small screws through pre-drilled holes.
Motherboard contains ports to connect all of the internal components. It provides a single socket for CPU. For memory, normally one or
more slots are available. Motherboards provide ports to attach floppy drive, hard drive and optical drives via ribbon cables. Mother
board carries fans and a special port designed for power supply.
There a peripheral card slots on front of the motherboard using which video cards, sound cards and other expansion cards can be
connected to motherboard.
On left side, motherboard carries a number of ports. These ports connect monitor, printer, mouse, keyboard, speaker, network cables
and all to the motherboard. Motherboards also provide USB ports which allow compatible devices to be connected in plug-in/plug-out
fashion. For example, pen drives digital cameras etc.

Computer - Memory Units


It is the amount of data that can be stored in the storage unit.



The storage capacities are expressed in terms of Bytes.

Following are the main memory storage units:
Sr. No.

Unit

Description

1

Bit (Binary
Digit)

A binary digit is logical 0 & 1 representing a passive or an active state of a
component in an electric circuit.

2

Nibble

A group of 4 bits is called nibble.

3

Byte

A group of 8 bits is called byte. A byte is the smallest unit which can
represent a data item or a character.

Word

A computer word like a byte is a group of fixed number of bits processed as
a unit which varies from computer but is fixed for each computer.
The length of a computer word is called word-size or word length and it may
be as small as 8 bits or may be as long as 96 bits.
A computer stores the information in the form of the computer words.

4

Few higher storage units are following
Sr.
No.

Unit

Description

1

Kilobyte (KB)

1 KB = 1024 Bytes

1

Megabyte (MB)

Exact Number of Bytes

1 MB = 1024 KB

2

10

= 1,024

2

20

= 1,048,576

30

1

GigaByte (GB)

1 GB = 1024 MB

2 = 1,073,741,824

1

TeraByte (TB

1 TB = 1024 GB

2 = 1,099,511,627,776

1

PetaByte (PB)

1 PB = 1024 TB

2 = 1,125,899,906,842,624

40
50

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Computer – Ports

Computer – Ports
What is a Port?


A computer port is a physical docking point using which an external device can be connected to the computer.



A computer port can also be programmatic docking point through which information flows from a program to computer or over
the internet.

Characteristics


External devices are connected to a computer using cables and ports.



Ports are slots on the motherboard into which a cable of external device is plugged in.



Examples of external devices attached via ports are mouse, keyboard, monitor, microphone, speakers etc.

Following are few important types of ports

Serial Port


Used for external modems and older computer mouse.



Two versions: 9 pin, 25 pin models.



Data travels at 115 kilobits per second.

Parallel Port


Used for scanners and printers



Also called printer port.



25 pin model.



Also known as IEEE 1284-compliant Centronics port.

PS/2 Port


Used for old computer keyboard and mouse



Also called mouse port.
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43

Computer – Ports



Most of the old computers provide two PS/2 port, each for mouse and keyboard.



Also known as IEEE 1284-compliant Centronics port.

Universal Serial Bus (or USB) Port


Can connect all kind of external USB devices such as external hard disk, printer, scanner, mouse, keyboard etc.



Introduced in 1997.



Most of the computers provide two USB port as minimum.



Data travels at 12 megabits per seconds



USB compliant devices can get power from a USB port

VGA Port


Connects monitor to a computer's video card.



Have 15 holes.



Similar to serial port connector but serial port connector has pins, it has holes.

Power Connector


Three-pronged plug



Connects to the computer's power cable that plugs into a power bar or wall socket.

Firewire Port


Transfer large amounts of data at very fast speed.



Connects camcorders and video equipment to the computer



Data travels at 400 to 800 megabits per seconds



Invented by Apple



Three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector and 9-Pin FireWire 800 connector

Modem


Connects a PC's modem to the telephone network.

Ethernet Port


Connects to a network and high speed Internet



Connect network cable to a computer.



This port resides on an Ethernet Card.



Data travels at 10 megabits to 1000 megabits per seconds depending upon the network bandwidth.

Game Port


Connect a PC to a joystick



Now replaced by USB.

Digital Video Interface, DVI port


Connect a Flat panel LCD monitors to the computer's high end video graphic cards.



Very popular among video card manufacturers.
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Computer – Hardware

Sockets


Connect microphone, speakers to sound card of the computer

Computer – Hardware
Hardware represents the physical and tangible components of the computer i.e. the components that can be seen and touched.
Examples of Hardware are following.



Input devices -- keyboard, mouse etc.



Output devices -- printer, monitor etc.



Secondary storage devices -- Hard disk, CD, DVD etc.



Internal components -- CPU, motherboard, RAM etc.

Relationship between Hardware and Software


Mutually dependent. Both of them must work together to make computer
produce a useful output.



Software cannot be utilized without supporting hardware.



Hardware without set of programs to operate upon cannot be utilized and is
useless.



To get a particular job done on the computer, relevant software should be
loaded into the hardware



Hardware is a one-time expense.



Software development is very expensive and is a continuing expense.



Different software can be loaded on hardware to run different jobs.



Software acts as an interface between the user and the hardware.



If hardware is the 'heart' of a computer system, then software is its 'soul’. Both are complimentary to each other.

Computer – Software
Software is a set of programs, which is designed to perform a well-defined function. A program is a sequence of instructions written to
solve a particular problem.
There are two types of software



System Software



Application Software

System Software or Operating System
The system software is collection of programs designed to
operate, control and extend the processing capabilities of the
computer itself. System software are generally prepared by
computer manufactures.
This software comprise of programs written in low level
languages which interact with the hardware at a very basic
level. System software serves as the interface between
hardware and the end users.
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Computer – Software
It is essentially the master controller for all the activities that takes place within a computer. It is referred to as a set of computer
programs that controls the computer hardware and acts as an interface with application programs.

Hardware

System Software

Application Software

User

Features of System Software are following



Close to system.



Fast in speed.



Difficult to design.



Difficult to understand.



Less interactive.



Smaller in size.



Difficult to manipulate.



Generally written in low level language.

Operating System Perform many different task often referred to as “SERVICES”. These services can be classified as either external or
internal.


External Services – It helps users start program, manage stored data and maintain security.



Internal Services – It is “behind the scenes” services to ensure that the computer system functions efficiently.

TWO CATEGORIES OF OPERATING SYSTEM


Desktop Operating System – it is also referred to as a client operating system. It is designed for single-user microcomputer.



Server Operating System – sometimes called “network operating system” is designed for computers that provide centralized
storage facilities and communications capabilities and Web Sites.

TYPES OF OPERATING SYSTEM


Real-Time Operating System - is a multitasking operating system that aims at executing real-time applications. The main
object of real-time operating systems is their quick and predictable response to events.



Multi-user vs. Single-user - A multi-user operating system allows multiple users to access a computer system concurrently.
Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time.



Multi-tasking vs. Single-tasking - When a single program is allowed to run at a time, the system is grouped under a singletasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multitasking operating system.
Two types of Multi-tasking
o

Pre-emptive - the operating system slices the CPU time and dedicates one slot to each of the programs.

o

Cooperative - is achieved by relying on each process to give time to the other processes in a defined manner.



Distributed - manages a group of independent computers and makes them appear to be a single computer.



Embedded - Embedded operating systems are designed to be used in embedded computer systems. They are designed to
operate on small machines like PDAs with less autonomy.

FUNCTIONS OF OPERATING SYSTEM


Schedule input and output operations



Schedule work of jobs according to priority



Communicate with human operator



Handle interruptions and monitors system status
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Computer – Software


Logs the jobs that are finished and currently being executed



Control system access and security functions



Facilitate in locating and debugging errors



Handle multiprogramming, so that several programs run at the same time.

EXAMPLES OF OPERATING SYSTEM FOR DESKTOP COMPUTERS
Microsoft PC Operating System
It is the most popular operating system for today’s microcomputers. Microsoft developed its first version of Windows which
provided graphical user interface (GUI) in the mid 1980s. Since then, it has continually updated its windows operating system.
Windows got its name from the rectangular work areas visible on screen. Each window can display a different document or program,
allowing you to work on more than one project at a time - a service is called multi-tasking.
Mac OS X
Since it was released in 1984 with Macintosh Computers, Apple’s Macintosh operating system has set the standard for
operating system ease of use and has been the model for most of the new GUIs developed for non-Macintosh systems. Mac OS is
used among Macintosh computers. Like windows, it also have evolved through many versions in which features have been modified
and added, including multitasking and support for small networks. The software that is compatible with Mac OS is referred to as
Macintosh software or “Mac Software for short. Special emulation hardware and software add-ons make it possible to run some
Windows software on a Macintosh computer, but performance is not optimal.
Disk operating system (DOS)
It was the first operating system used. It was strictly text based, command driven operating system. It was developed by
Microsoft for IBM PCs under the name PC-DOS. Later MS DOS was developed for non- IBM PCs. Contrary to the popular opinion;
DOS is not yet dead as it has been incorporated into windows. DOS operates behind the scenes, however, windows user does not
have to memorize and type complex commands.
Linux
Linux is an operating system developed by Linux Torvalds in 1991 as student in Finland. The OS is under the GNU General
Public License, and its source code is freely available to everyone. Linux is available over the internet and from other sources, including
Red Hat Linux and SCO Open Linux.

EXAMPLE OF OPERATING SYSTEM FOR SERVERS
Windows server 2003
Microsoft designed Windows Server 2003 to do a host of new task that are vital for websites and corporate Web Application on
the internet. They coordinate large data centers and prevent unauthorized disclosure of information by blocking text and e-mails from
being copied, printed or forwarded to other people.
Unix
Was developed in 1969 as a minicomputer operating system, but has since become popular for network and web servers of all
sizes. A variation of UNIX called Linux, has been recently gained prominence as a server operating system for minicomputers. It is
available as a freeware. It also provides a secure and stable operating environment.
Mac OS X Server
It is the first modern OS from Apple Computer that provides UNIX style process management. Protected memory puts each
service in its own well-guarded chunks of dynamically allocated memory, preventing a single process from going awry and bringing
down the system or other devices.
Solaris
Solaris is a network operating system developed by Sun Microsystems. Specifically, it is designed for e-commerce
applications. Solaris manages high-traffic accounts and incorporates security necessary for Web transaction ns. Client computers often
use desktop programs such as GNOME desktop that communicates with the Solaris operating system.
Netware
It is a server operating system designed specifically for microcomputer networks which is sold by Novell. It is considered ideal
in situation where many users must access document or other data files from a centrally located computer.

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47

Computer – Software

Application Software
Application software is the software that is designed to satisfy a particular need of a particular environment. All software prepared by us
in the computer lab can come under the category of Application software.
Application software may consist of a single program, such as a Microsoft's notepad for writing and editing simple text. It may also
consists of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet
package.
Examples of Application software are following



Payroll Software



Student Record Software



Inventory Management Software



Income Tax Software



Railways Reservation Software



Microsoft Office Suite Software



Microsoft Word



Microsoft Excel



Microsoft PowerPoint

Features of Application Software are following



It is close to user.



It is easy to design.



More interactive.



Slow in speed.



Generally written in high level language.



Easy to understand.



Easy to manipulate and use.



Bigger in size and requires large storage space.

FORMS OF APPLICATION SOFTWARE
Packaged Software – It is mass-produced, copyrighted retail software that meets the needs of a variety of users, not just a single user
or company. It is available in retail stores or on the Web.
Custom Software – It performs functions specific to a business or industry. Sometimes a company cannot find packaged software that
meets its unique requirements. In this case, the company may use programmers to develop tailor-made custom software.
Open Source Software – It is software provided for use, modification and redistribution. This software has no restrictions from the
copyright holder regarding modification of the internal instructions and redistribution of the software. It usually can be downloaded from
the internet, sometimes at no cost.
Shareware – It is copyrighted software that is distributed at no cost for a trial period. To use a shareware beyond that period, payment
must be sent to the program developer.
Freeware – It is copyright software provided at no cost by an individual or a company that retains all rights to the software.
Public-Domain Software – It has been donated for public use and has no copyright restrictions. Anyone can copy or distribute publicdomain software to others at no cost.

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48

Peopleware

Peopleware
Peopleware – It refers to the person engaged in various processes of computer operations, programming and system analysis,
maintenance and implementation.
Positions in the IT department usually divided into five main areas
1.

Management – It directs the planning, research, development, evaluation and integration of technology.
a.

Job Title under Management
 CIO (Chief Information Officer)
 E-commerce administrator
 Network Administrator
 Project Leader/Manager

2.

System Development and Programming – It analyzes designs, develops and implement new information technology and
maintains and improves existing systems.
a.

Job Title under System Development and Programming
 Application programmer
 Computer Scientist
 Database Analyst
 Software Engineer
 System Analyst
 System Programmer
 Technical writer
 Technical lead
 Web Page author

3.

Technical Services – They evaluate and integrate new technologies, administer the organization’s data resources, and support
the centralized computer operating system and servers.
a.

Job Title under Technical Services
 Computer Forensic specialist
 Computer Technician
 Desktop Publisher
 Database Administrator
 Quality Assurance Specialist
 Web Administrator

4.

Operations – operates the centralized computer equipment and administer the network, including both data and voice
communications.
a.

Job Title under Operations
 Computer Operator
 Data Communication Analyst

5.

Training – They teach employees how to use components of the information system and answers specific user questions.
a.

Job Title under Training
 Corporate Trainer
 help desk specialist

Computer - Number System
When we type some letters or words, the computer translates them in numbers as computers can understand only numbers.
A computer can understand positional number system where there are only a few symbols called digits and these symbols represent
different values depending on the position they occupy in the number.
A value of each digit in a number can be determined using



The digit
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49

Computer - Number System



The position of the digit in the number



The base of the number system (where base is defined as the total number of digits available in the number system).

Decimal Number System
The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10
digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds,
thousands and so on.
Each position represents a specific power of the base (10). For example, the decimal number 1234 consists of the digit 4 in the units
position, 3 in the tens position, 2 in the hundreds position, and 1 in the thousands position, and its value can be written as
(1x1000)+ (2x100)+ (3x10)+ (4xl)
3

2

1

0

(1x10 )+ (2x10 ) + (3x10 ) + (4xl0 )
1000 + 200 + 30 + 4
1234
As a computer programmer or an IT professional, you should understand the following number systems which are frequently used in
computers.

S.N. Number System & Description

1

Binary Number System
Base 2. Digits used: 0, 1

2

Octal Number System
Base 8. Digits used: 0 to 7

4

Hexa Decimal Number System
Base 16. Digits used: 0 to 9, Letters used: A- F

Binary Number System
CHARACTERISTICS


Uses two digits, 0 and 1.



Also called base 2 number system



Each position in a binary number represents a 0 power of the base (2). Example 2



Last position in a binary number represents an x power of the base (2). Example 2 where x represents the last position - 1.

x

EXAMPLE
Binary Number: 101012
Calculating Decimal Equivalent:
Step

0

Binary Number

Decimal Number
4

3

2

1

0

Step 1 101012

((1 x 2 ) + (0 x 2 ) + (1 x 2 ) + (0 x 2 ) + (1 x 2 ))10

Step 2 101012

(16 + 0 + 4 + 0 + 1)10

Step 3 101012

2110

Note: 101012 are normally written as 10101.

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50

Computer - Number Conversion

Octal Number System
CHARACTERISTICS


Uses eight digits, 0,1,2,3,4,5,6,7.



Also called base 8 number system



Each position in an octal number represents a 0 power of the base (8). Example 8



Last position in an octal number represents an x power of the base (8). Example 8 where x represents the last position - 1.

0
x

EXAMPLE
Octal Number: 125708
Calculating Decimal Equivalent:
Step

Octal Number

Decimal Number
4

3

2

1

0

Step 1 125708

((1 x 8 ) + (2 x 8 ) + (5 x 8 ) + (7 x 8 ) + (0 x 8 ))10

Step 2 125708

(4096 + 1024 + 320 + 56 + 0)10

Step 3 125708

549610

Note: 125708 is normally written as 12570.

Hexadecimal Number System
CHARACTERISTICS


Uses 10 digits and 6 letters, 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.



Letters represents numbers starting from 10. A = 10. B = 11, C = 12, D = 13, E = 14, F = 15.



Also called base 16 number system



Each position in a hexadecimal number represents a 0 power of the base (16). Example 16



Last position in a hexadecimal number represents an x power of the base (16). Example 16 where x represents the last

0
x

position - 1.

EXAMPLE
Hexadecimal Number: 19FDE16
Calculating Decimal Equivalent:
Step

Binary Number

Decimal Number
4

3

4

3

2

1

0

Step 1 19FDE16

((1 x 16 ) + (9 x 16 ) + (F x 16 ) + (D x 16 ) + (E x 16 ))10

Step 2 19FDE16

((1 x 16 ) + (9 x 16 ) + (15 x 16 ) + (13 x 16 ) + (14 x 16 ))10

Step 3 19FDE16

(65536+ 36864 + 3840 + 208 + 14)10

Step 4 19FDE16

10646210

2

1

0

Note: 19FDE16 is normally written as 19FDE.

Computer - Number Conversion
There are many methods or techniques which can be used to convert numbers from one base to another. We'll demonstrate here the
following



Decimal to Other Base System
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51

Computer - Number Conversion



Other Base System to Decimal



Other Base System to Non-Decimal



Shortcut method - Binary to Octal



Shortcut method - Octal to Binary



Shortcut method - Binary to Hexadecimal



Shortcut method - Hexadecimal to Binary

Decimal to Other Base System
STEPS
Step 1 - Divide the decimal number to be converted by the value of the new base.
Step 2 - Get the remainder from Step 1 as the rightmost digit (least significant digit) of new base number.
Step 3 - Divide the quotient of the previous divide by the new base.
Step 4 - Record the remainder from Step 3 as the next digit (to the left) of the new base number.
Repeat Steps 3 and 4, getting remainders from right to left, until the quotient becomes zero in Step 3.
The last remainder thus obtained will be the most significant digit (MSD) of the new base number.

EXAMPLE
Decimal Number: 2910
Calculating Binary Equivalent:
Step

Operation

Result

Remainder

Step 1

29 / 2

14

1

Step 2

14 / 2

7

0

Step 3

7/2

3

1

Step 4

3/2

1

1

Step 5

1/2

0

1

As mentioned in Steps 2 and 4, the remainders have to be arranged in the reverse order so that the first remainder becomes the least
significant digit (LSD) and the last remainder becomes the most significant digit (MSD).
Decimal Number: 2910 = Binary Number: 111012.

Other base system to Decimal System
STEPS
Step 1 - Determine the column (positional) value of each digit (this depends on the position of the digit and the base of the number
system).
Step 2 - Multiply the obtained column values (in Step 1) by the digits in the corresponding columns.
Step 3 - Sum the products calculated in Step 2. The total is the equivalent value in decimal.

EXAMPLE
Binary Number: 111012
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52

Computer - Number Conversion
Calculating Decimal Equivalent:
Step

Binary Number

Decimal Number

Step 1

111012

((1 x 2 ) + (1 x 2 ) + (1 x 2 ) + (0 x 2 ) + (1 x 2 ))10

Step 2

111012

(16 + 8 + 4 + 0 + 1)10

Step 3

111012

2910

4

3

2

1

0

Binary Number: 111012 = Decimal Number: 2910

Other Base System to Non-Decimal System
STEPS
Step 1 - Convert the original number to a decimal number (base 10).
Step 2 - Convert the decimal number so obtained to the new base number.

EXAMPLE
Octal Number: 258
Calculating Binary Equivalent:

STEP 1: CONVERT TO DECIMAL
Step

Octal Number

Decimal Number

Step 1

278

((2 x 8 ) + (5 x 8 ))10

Step 2

278

(16 + 5 )10

Step 3

278

2110

1

0

Octal Number: 258 = Decimal Number: 2110

STEP 2: CONVERT DECIMAL TO BINARY
Step

Operation

Result

Remainder

Step 1

21 / 2

10

1

Step 2

10 / 2

5

0

Step 3

5/2

2

1

Step 4

2/2

1

0

Step 5

1/2

0

1

Decimal Number: 2110 = Binary Number: 101012
Octal Number: 258 = Binary Number: 101012

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53

Computer - Number Conversion

Shortcut method - Binary to Octal
STEPS
Step 1 - Divide the binary digits into groups of three (starting from the right).
Step 2 - Convert each group of three binary digits to one octal digit.

EXAMPLE
Binary Number: 101012
Calculating Octal Equivalent:
Step

Binary Number

Octal Number

Step 1

101012

010 101

Step 2

101012

28 58 38

Step 3

101012

258

Binary Number: 101012 = Octal Number: 258

Shortcut method - Octal to Binary
STEPS
Step 1 - Convert each octal digit to a 3 digit binary number (the octal digits may be treated as decimal for this conversion).
Step 2 - Combine all the resulting binary groups (of 3 digits each) into a single binary number.

EXAMPLE
Octal Number: 258
Calculating Binary Equivalent:
Step

Octal Number

Binary Number

Step 1

258

210 510

Step 2

258

0102 1012

Step 3

258

0101012

Octal Number: 258 = Binary Number: 101012

Shortcut method - Binary to Hexadecimal
STEPS
Step 1 - Divide the binary digits into groups of four (starting from the right).
Step 2 - Convert each group of four binary digits to one hexadecimal symbol.

EXAMPLE
Binary Number: 101012
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Computer - Data & information
Calculating hexadecimal Equivalent:
Step

Binary Number

Hexadecimal Number

Step 1

101012

0001 0101

Step 2

101012

110 510

Step 3

101012

1510

Step 5

101012

F16

Binary Number: 101012 = Hexadecimal Number: F16

Shortcut method - Hexadecimal to Binary
STEPS
Step 1 - Convert each hexadecimal digit to a 4 digit binary number (the hexadecimal digits may be treated as decimal for this
conversion).
Step 2 - Combine all the resulting binary groups (of 4 digits each) into a single binary number.

EXAMPLE
Hexadecimal Number: F16
Calculating Binary Equivalent:
Step

Hexadecimal Number

Binary Number

Step 1

F16

1510

Step 2

F16

110 510

Step 3

F16

00012 01012

Step 4

F16

000101012

Hexadecimal Number: F16 = Binary Number: 101012

Computer - Data & information
What is Data?
Data can be defined as a representation of facts, concepts or instruction in a formalized manner which should be suitable for
communication, interpretation or processing by human or electronic machine.
Data is represented with the help of characters like alphabets (A-Z,a-z), digits (0-9) or special characters(+,-,/,*,<,>,= etc).

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Computer - Data & information

What is Information?
Information is organized or classified data so that it has some meaningful values to
the receiver.
Information is the processed data on which decisions and actions are based.
For the decision to be meaningful, the processed data must qualify for the following
characteristics



Timely - Information should be available when required.



Accuracy - Information should be accurate.



Completeness - Information should be complete.

Data Processing Cycle
Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness & add values for particular
purpose.
Data processing consists of basic steps input, processing and output. These three steps constitute the data processing cycle.



Input - In this step the input data are prepared in some convenient
form for processing. The form will depend on the processing machine.
For example, when electronic computers are used, the input data
could be recorded on any one of several types of input medium, such
as magnetic disks, tapes and so on.



Processing - In this step input data are changed to produce data in a
more useful form. For example, pay-checks may be calculated from
the time cards, or a summary of sales for the month may be
calculated from the sales orders.



Output -Here the result of the proceeding processing step are
collected. The particular form of the output data depends on the use
of the data. For example, output data may be pay-checks for employees.

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56

Computer – Networking

Computer – Networking
What is a Computer Network?
A computer network is a system in which multiple computers are
connected to each other to share information and resources.

Characteristics


Share Resources from one computer to another



Create files and store them in one computer, access those
files from the other computer(s) connected over the network



Connect a printer, scanner, or a fax machine to one computer within the network and let other computers of the network use
the machines available over network.

Following is the list of hardware required to setup a computer network.



Network Cables



Distributors



Router



Internal Network Cards



External Network Cards

Network Cables


Network cables are used to connect computers. The most commonly used cable is

Category 5 cable RJ-45.

Distributors


Each and every computer can be

connected to another one via a

serial port but if we need to connect

many

network, this serial connection will not

work. The solution is to use a central

body

printers,

to

which

other

computers,

connected and, and then this body will

computers

scanners

to

produce

etc.

can

a

be

manage or distribute network traffic.

Router


A router is a type of device which acts as the central point among computers and

other devices that are part of a network.



A router is equipped with holes called ports.



Computers and other devices are connected to a router using network cables.



Now-a-days router comes in wireless modes using which computers can be

connected without any physical cable.

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57

Computer - Operating System

Network Card


Network card is a necessary component of a computer without which a computer cannot be connected over a network.



Also known as network adapter or Network Interface Card (NIC).



Most of branded computers have network card pre-installed.



Network cards are of two types: Internal and External Network Cards

Internal Network Cards


Motherboard has a slot for internal network card where it is to be inserted.



Internal network cards are of two types.



First type uses Peripheral Component Interconnect (PCI) connection.



Second type uses Industry Standard Architecture (ISA).



Network cables are required to provide network access

External Network Cards


Comes in two flavors: Wireless and USB based.



Wireless network card need to inserted into the motherboard but no network

cable is required to connect to network.



USB card, are easy to use and connect via USB port.



Computer automatically detects USB card and can install the drivers required to support the USB network card automatically.

Computer - Operating System


An operating system is a program that acts as an interface between the software and the
computer hardware.



It is an integration set of specialized programs that are used to manage overall resources and
operations of the computer.
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58

Computer - Internet & Intranet



It is specialized software that controls and monitors the execution of all other programs that reside in the computer, including
application programs and other system software.

Objectives of Operating System


Making a computer system convenient to use in an efficient manner



To hide the details of the hardware resources from the users



To provide users a convenient interface to use the computer system.



To act as an intermediary between the hardware and its users and making it easier for the users to access and use other
resources.



Manage the resources of a computer system.



Keep track of who is using which resource, granting resource requests, according for resource using and mediating conflicting
requests from different programs and users.



The efficient and fair sharing of resources among users and programs

Characteristics of Operating System


Memory Management -- It keeps tracks of primary memory i.e what part of it are in use by whom, what part are not in use etc.
Allocates the memory when the process or program requests it.



Processor Management -- Allocate the processor (CPU) to a process. Deallocate processor when processor is no longer
required.



Device Management -- Keep tracks of all devices. This is also called I/O controller. Decides which process gets the device
when and for how much time.



File Management -- Allocates the resources. De-allocates the resource. Decides who gets the resources.



Security -- By means of passwords & similar other techniques, preventing unauthorized access to programs & data.



Job accounting -- Keeping track of time & resources used by various jobs and/or users.



Control over system performance -- Recording delays between request for a service & from the system.



Interaction with the operators -- The interaction may take place via the console of the computer in the form of instructions.
Operating System acknowledges the same, do the corresponding action and inform the operation by a display screen.



Error-detecting aids -- Production of dumps, traces, error messages and other debugging and error-detecting methods.



Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and
other software to the various users of the computer systems.

Computer - Internet & Intranet
Internet


Internet is a world-wide / global system of interconnected computer networks.



Internet uses the standard Internet Protocol (TCP/IP)



Every computer in internet is identified by a unique IP address.



IP Address is a unique set of numbers (such as 110.22.33.114) which
identifies a computer location.



A special computer DNS (Domain Name Server) is used to give name to the
IP Address so that user can locate a computer by a name.



For

Example,

a

DNS

server

will

resolve

a

name http://www.tutorialspoint.com to a particular IP address to unique
identify the computer on which this website is hosted.
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59

Computer - Internet & Intranet



Internet is accessible to every user all over the world.

Intranet


Intranet is system in which multiple PCs are networked to be connected to each
other.



PCs in intranet are not available to the world outside of the intranet.



Usually each company or organizations have their own Intranet network and
members/employees of that company can access the computers in their intranet.



Each computer in Intranet is also identified by an IP Address which is unique
among the computers in that Intranet.

Similarities in Internet & Intranet


Intranet uses the internet protocols such as TCP/IP and FTP.



Intranet sites are accessible via web browser in similar way as websites in internet. But only members of Intranet network can
access intranet hosted sites.



In Intranet, own instant messengers can be used as similar to yahoo messenger/ gtalk over the internet.

Differences in Internet & Intranet


Internet is general to PCs all over the world where Intranet is specific to few PCs.



Internet is wider access and provides a better access to websites to large population whereas Intranet is restricted.



Internet is not as safe as Intranet as Intranet can be safely privatized as per the need.

Page 59 of 59