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Published by PHILOMATH Contextualizing Mathematics, 2021-07-14 10:11:04

Let's Log In Computer Science Book 8 Revised (2078).indd

Let's Log In Computer Science Book 8 Revised (2078).indd

Approved by the Government of Nepal, Ministry of Education, Science and Technology, Curriculum
Development Centre, Sanothimi, Bhaktapur as an Additional Learning Material

vedanta

Computer Science

Book

Authors:

Sunil Kumar Gharti Sushil Upreti

vedanta

Vedanta Publication (P) Ltd.
jb] fGt klAns;] g k|f= ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
info@vedantapublication.com.np
www.vedantapublication.com.np

vedanta Book

Let's Log in

Computer Science

All rights reserved. No part of this publication may be reproduced, copied or
transmitted in any way, without the prior written permission of the publisher.

Authors: Sushil Upreti
Sunil Kumar Gharti

© Vedanta Publication (P.) Ltd.

Design: Manoz Manohar
First Edition: BS 2077 (2020 AD)
Second Edition: BS 2078 (2021 AD)

Printed in Nepal

Published by:

Vedanta Publication (P) Ltd.
jb] fGt klAns];g k|f= ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
info@vedantapublication.com.np
www.vedantapublication.com.np

Preface

This is the age of information. Information Technology
has undoubtedly invaded all walks of life to such an extent
that computer and information literacy has become the
fundamental part of our daily activities. Computer Science
is now an essential addition to the school curriculum at all
levels.

Vedanta Let's Log in (A course in Computer Science)
is a series of ten books on Computer Science for basic
and secondary level students, designed for the need of
new generation to help acquire knowledge on the theory,
application and programming aspects of computing. This
series is based on the new syllabus of Computer Science,
designed and approved as per the curriculum prescribed
by Curriculum Development Center, Ministry of Education,
Government of Nepal.

The series covers the history of computer, its accessories,
applications and programming in LOGO and QBASIC in
a step-by-step and graded manner following logical and
scienti ic approach. Concept of graphic and web design is
also illustrated with many practical examples. This series not
only assists the students and the teachers in the class but also
incorporates latest information and developments in IT with
the present need of the students in Nepal. It also provides
other enthusiasts and learners with the skill and knowledge
to cope up with the growing demand of IT skills in market
and daily life.

We earnestly hope that the students would ind the journey
through this series an enjoyable experience and gain a sound
working knowledge on the basic aspects of computing and
information technology.

As far as possible, we have sincerely put in our efforts to
make the book error free. However, there is always scope
for improvement. Constructive criticism and feedback are
always welcome.

Authors

Content

Lesson Topics Page
No.
1 Computer History and Generation
2 Types of Computer 5
3 Computer Software 27
4 Number System 36
5 Advanced Features of Word Processor 47
6 Spreadsheet 58
7 Presentation Software 85
8 ICT, Cyber Law and Computer Ethics 111
9 Computer Virus 134
10 Data Communication and Computer Network 140
11 Introduction to Web Design 147
12 Computer Graphics 169
13 Concept of Computer Programming 192
14 Program Design Tools 212
15 Programming in QBASIC 216
229
Abbreviations 251
Model Questions for Grade VIII 253

Vedanta Let’s Log in Computer Science | Book 8

Lesson

1

Overview : Computers in Our World

Consider this sentence: “Computers are everywhere.” Does it sound like
an overstatement? No matter how you perceive the impact of computers,
the statement is true. Computers are everywhere. In fact, you can find
them in some pretty unlikely places, including your family car, your home
appliances, and even your alarm clock!

Computers

Computer development is one of the greatest scientific achievements
in today’s world: it has become a necessity for everyone to know about
computers. In basic terms, a computer is an electronic device that processes
data, converting it into useful information to people. Any computer is
controlled by programmed instructions, which give the machine a purpose
and tell it what to do.

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Function of Computer

All computers essentially perform three basic functions. These are:

Input Process Output

IPO

Computer works on the basis of input, process, and output cycle. The three
terms, i.e. input, process, and output, are interrelated. The raw information
flows from the input device (like 6 x 3) to the processing device to become
meaningful information and then panes (18) through output device. This
whole flow of information cycle is known as Input - Process – Output or IPO
(Input – Process – Output) cycle.

History of Computer

If we see computer historically, we
can see that they do not have similar
technology, shape, size, functionality,
etc. So, computer that we use at present
differs from computer in the past. The
origin of computer starts from counting.
A short description of the development
process of computer is described below:
People used to move from one place to another with their cattle and they
did not have fixed place to stay. They used fingers, symbol, pebbles, etc.
for counting but it was difficult to do large calculation. So, they developed
different devices from different parts of world to do complex calculations.
The origin of computer starts from counting.
The computer historically does have similar technology, shape, size,
functionality, etc. So, computer that we use at present differs from computer
in the past. A short description about the development process of computer
is described below as

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a. Mechanical Devices
b. Electromechanical Devices
c. Electronic Devices

Mechanical Devices

Mechanical devices are used for the purpose of counting manually. The main
devices are described as below

Abacus

Many centuries ago when man
started to count the numbers, he
thought of a device which can trace
the numbers and thus came the
existence of Abacus. Abacus is
known to be the first mechanical
calculating device which was
used to be performed addition and
subtraction easily. This device was a Abacus

first developed by the Egyptians and Chinese about 3000 years ago. Abacus
is made up of wooden frame in which rod where fitted across with rounds
beads sliding on the rods. It was divided into two parts called “Heaven” and
“Earth”. Heaven was the upper part and Earth was the lower one which
was separated by mid bar. Thus Counting was done by moving the beads
from one end of the frame to the other.

Napier’s Bones

Napier’s bone is a device which contains a set of rods made of bones. It was
developed by John Napier in 1617 A.D, by Scottish Mathematician and
Hence, the device was named as Napier’s bones. The device was mainly
developed for performing multiplication and division. In 1614, he also
introduced logarithms. There are ten bones corresponding to the digits
0-9, and a special eleventh bone that is used to represent the multiplier.
The multiplier bone is simply a list of the digits 1-9 arranged vertically
downward. The remainder of the bones each has a digit written in the top
square, with the multiplication table for that digits are written downward,

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with the digits split by a diagonal line going from the lower left to the upper
right. In practice, multiple sets of bones were needed for multiplication of
numbers containing repeated digits.

Napiers Bones

Slide Rule

The slide rule was invented by William
Oughtred in 1620. He was an English
mathematician. Slide Rule was the
first analog device used the principle
of logarithms. It could perform simple
multiplication and division. It consists of 2
sets of rulers joined together with a marginal
space between them. The proper alignment Slide Rule

of two rulers enables to perform multiplication and division by the method
of addition and subtraction.

Pascaline

Pascaline is a calculating machine developed by a French mathematician
Blaise Pascal in 1642. It was the first device with an ability to perform

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additions and subtractions on whole Pascaline
numbers. The device was made
up of interlocked cogwheels which
contain numbers from 0 to 9 on its
circumference. When one wheel
completes its rotation the other
wheel moves by one segment which
is still used in water meters and
odometers nowadays.

Stepped Reckoner

Stepped Reckoner was a calculating
machine designed in 1671 and built-
in 1673 by a German mathematician,
Gottfried Wilhelm Von Leibniz.
The Stepped Reckoner expanded
on the French mathematician-
philosopher Blaise Pascal’s ideas
and did multiplication by repeated
addition and shifting. It was the Stepped Reckoner

first calculator that could perform addition, subtraction, multiplication,
and division. Even square roots could be calculated by series of stepped
additions.

Jacquard's Loom

A French inventor, Joseph Marie Jacquard
invented an automatic weaving machine called
Loom in 1801. This loom used punched cards to
produce certain pattern in the woven cloth. The
function of loom depended upon the absence or
presence of holes on the punched cards. This
concept of loom gave the idea of Binary Digits, 0
or 1 (Yes and No). This concept can be considered
as an important contribution to the evolution of
the modern computer.

Jacquard's Loom

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Difference Engine and Analytical Engine

In 1822 A.D., Charles Babbage, a Professor of Mathematics at Cambridge
University, devised an automatic calculating machine called Differential
Engine. This machine was used to perform simple computation needed for
setting up trigonometric and logarithmic tables.

Difference Engine Charles Babbage Analytical Engine

Babbage’s next idea was the Analytical Engine designed in 1833 A.D.
It was first general purpose, fully programmable, automatic, mechanical
computer that could solve any mathematical problem. Babbage’s projects
could not be completed due to the lack of required technologies at that
time. It is still found in the Science Museum, London. He had developed a
prototype computer, which was 100 years ahead of its time. He is, therefore,
well known as the Father of Modern Day Computers. Babbage concept
led to develop a first mechanical computer Mark-I in the year 1937A.D.

Lady Augusta Ada Lovelace Lady Augusta Ada Lovelace

Lady Augusta Ada Lovelace was the first
computer programmer. She helped Charles
Babbage to write programs for his Analytical
Engine. In 1848, she made first programming
language for Analytical Engine. She has
suggested Babbage to use binary number system
for programs and data in his machine. Because
of her first initiative in the development of
programming concept, she is honoured as the

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first Computer Programmer. In 1979, the US Department of Defense
named a programming language ADA to honour her.

Tabulating Machine

An American census statistician, Herman
Hollerith developed Tabulating Machine in
1887. The machine was used to tabulate US
census record in 1890. The tabulation process
was completed only in 3 years by the use of
this machine which takes approximately 10
years without the use of machine. Tabulating
Machine was the first to make practical use of
the punched card in data processing. Inventor
Herman Hollerith formed the Tabulating
Machine Company in 1896. to manufacture his
inventions. The Tabulating Machine Company Tabulating Machine

with other two companies merged in 1924. to form International Business
Machine (IBM), largest computer manufacturing company.

Mark-I

Howard Aiken, Professor of Harvard Mark-I
University developed an automatic
calculating device known as Mark-I
in 1937. The machine was put in
operation only in 1944 and technically
named as Automatic Sequence
Controlled Calculator (ASCC). It
was the first electromechanical
computer. It was 51ft. long, 8ft.
tall, and 3ft. wide. It contained 18000
vacuum tubes.

Atanasoff Berry Computer (ABC)

Atanasoff Berry Computer (ABC) is considered the first electronic digital
computer. Professor John Vincent Atanasoff and his graduate student Cliff

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Berry developed the ABC in 1937 at
the Iowa State College (now Iowa
State University). It was developed
for solving simultaneous equations.
It uses 18000 vacuum tubes to store
data in the memory.

Atanasoff Berry Computer

Electronic Numerical Integrator and Calculator (ENIAC)

Electronic Numerical Integrator and Calculator (ENIAC) was the first
electronic computer used for general purposes such as solving
numerical problems. It was invented by J. Presper Eckert and John
Mauchly in 1946 at the University of Pennsylvania, U.S.A., to calculate
artillery firing tables for the United States Army’s Ballistic Research
Laboratory.
Although it was not completed until the end of World War II, the ENIAC
was created to help with the war effort against German forces.

Electronic Numerical Integrator and Calculator
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Electronic Discrete Variable Automatic Computer (EDVAC)

A major drawback of ENIAC was that its programs were wired on boards
that made it difficult to change the programs. Dr. John Von Neumann
later introduced the “stored program” concept that helped in
overcoming this problem. The basic idea behind this concept is that a
sequence of instructions and data can be stored in the memory of computer
for automatically directing the flow of operations. This feature considerably
influenced the development of modern digital computers because of the ease
with which different programs can be loaded and executed on the same
computer. Due to this feature, we often refer to modern digital computers
as stored program digital computers. The Electronic Discrete Variable
Automatic Computer (EDVAC) used the stored program concept in its
design. Von Neumann also is credited for introducing the idea of storing
both instructions and data in binary form (a system that uses only two
digits – 0 and 1 to represent all characters), instead of decimal numbers or
human readable words.

Electronic Discrete Variable Automatic Computer

Electronic Delay Storage Automatic Computer (EDSAC)

EDSAC was the first operational stored program computer developed
by Professor Maurice Wilkes and his team. It was started in 1947. and
the first program was executed in 1949. at Mathematical Laboratory, the

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University of Cambridge. It contained 6000 vacuum tubes and it required 30
kilowatts of electric power. This program used input using paper tape and
output results were printed on a teletype page printer. It was the computer
that ran the first graphical computer game nicknamed “Baby.”

Electronic Delay Storage Automatic Computer

Universal Automatic Computer (UNIVAC-I)

UNIVAC-I was developed by John William Mauchly, John Presper Eckert
in 1951. It was the first general purpose electronic digital computer
for commercial users. It could handle both numbers and alphabets. This
computer consisted of magnetic tape for data input and output. This
computer was used for data processing until 1963. in America. The UNIVAC
was later released the UNIVAC II
and III with various models. UNIVAC
marked the arrival of commercially
available digital computers for
business and scientific applications.

All the above discussed conspicuous
contributions were considered
relevant in the development of today’s
computers.

Universal Automatic Computer

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History of Computers in Nepal

There is not a long history of computer
in Nepal. Nepal hired some types
of calculators and computers for its
census calculation. Following list
shows its history in Nepal. In 2028 BS
census, IBM 1401, a second generation
mainframe computer, was used.
In 2031 BS, a center for Electronic
Data Processing, Later renamed to
National Computer Center (NCC),was
established for national data
processing and computer training.· History of Computers in Nepal

In 2038 BS, ICL 2950/10, a second generation mainframe computer, was
used for census.· Nowadays, probably each and every institution, business
organization, communication center, ticket counter, etc., are using computers.

After 2039 B.S., microcomputers such, as Sirus, Vector, IBM, Apple, etc.,
were imported by private companies and individuals in Nepal. Today
there are thousands of computer training institutes, and computer sales
and repair centers in Nepal. Different universities are opening IT colleges
in Nepal. Computer is included as subject in the curriculum of school and
colleges by CDC.

High-Level Commission for Information Technology (HLCIT) is body
formed under the chairmanship of Rt. Hon. Prime Minister of Nepal
with a view to providing crucial strategic direction and helping formulate
appropriate policy responses for the development of ICT (Information and
Communication Technology) sector. IT policy is also formulated in 2057 B.S.
and revised in 2072 B.S. (2015).

The First Computer Mouse was Made of Wood Doug Engelbart invented it in 1964.

People Blink Less When They Use Computers While the average person blinks about
20 times a minute under normal circumstances, people on computers only blink
about seven times a minute.

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Generation of Computer

The modern computer which we have today is not result of the first attempt
by the engineers and mathematicians. It has taken a big leap forward with
each technological breakthrough during the process of development. The
functions and speed of operation. It has been changing in computers. Also,
the size and cost also have been changing. Technological breakthrough in
hardware and software has brought more and more advanced computer
system. There are five major stages in the continuous development process
of the computer generations. Each generation is based on particular
technological class.

1st Generation 2nd Generation 4th Generation 5th Generation
Vaccum tubes Transistors Micro Processor Bio Chip

3rd Generation : Integrated Circuits

1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060

Generation Time line from 1940 to present

Generation Time Main Component
First Generation 1940 to 1955 Vacuum tube
Second Generation 1956 to 1964 Transistors
Third Generation 1965 to 1971 Integrated Circuits
Fourth Generation 1972 to 2010 Micro Processor
Fifth Generation 2010 to present Bio Chip

First Generation of Computers

The period of the first generation was from 1940 to 1955. The technology
used in these computers was Vacuum Tube. This technology was first
developed by Lee De Forest. First generation computers relied on machine
language to perform operations: they could only solve one problem at a
time. In this generation, mainly batch processing operating system was
used. Input was based on punched cards and paper tape, and output was

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displayed on printouts. ENIAC, EDVAC, EDSAC, UNIVAC-I, IBM 650,
701 are examples of this generation computers.

Vaccum tubes

Features of the first generation computers

Vacuum tube as the main electronic component.
Supported machine language only and huge size.
Slow in speed and had less storage capacity.

Second Generation of Computers

The period of the second generation was
from 1956 to 1964. In this generation,
transistors were used (developed by three
scientists William Shockley, John
Bardeen, and Walter Brattain). The
computers consumed less power. They
were more compact in size, cheaper in
price, more reliable and faster in function.
In this generation, magnetic cores
were used as the primary memory and Transistors

magnetic tape and magnetic disks as secondary storage devices. In this
generation, assembly language and high-level programming languages like
FORTRAN, COBOL were used. The computers used batch processing and
multiprogramming operating system. Some computers of this generation
were IBM 1620, CDC 1604, UNIVAC 1108, CDC 3600, etc.

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Features of the second generation computers

Use of transistors and supported machine and assembly languages.
Smaller size, faster, reliable in comparison to the first generation

computers.
Consumed less electricity and generated less heat as compared to first

generation computers.
First computers of this generation were developed for the atomic energy

industry.

Third Generation of Computers

The period of the third generation was from
1965 to 1971. The computers of this generation
used Integrated Circuits (ICs) in place of
transistors. A single IC has many transistors,
resistors, and capacitors along with the
associated circuitry. The IC was invented by
Jack Kilby. This development made computers
smaller in size, reliable, and efficient. In this
generation, remote processing, time-sharing, Integrated circuit

multiprogramming operating system was
used. High-level languages as FORTRAN, COBOL, PASCAL and BASIC
were used during this generation. Some computers of this generation were
Honeywell-6000 series, IBM-370/168, ICL 900 Series, IBM-360, etc.

The main features of the third generation are
Use of IC, smaller size, faster and generating less heat
More reliable in comparison to previous two generations
Lesser maintenance and consumption of less electricity
Supported high-level language

Fourth Generation of Computers

The period of the fourth generation was from 1972 to 2010. The technology
used in these computers was Microprocessor (LSIC = Large Scale
Integration Circuit, VLSIC=Very Large Scale Integration Circuit). This

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technology was first developed by American Intel Corporation in 1971. The
microprocessor brought the fourth generation of computers, as thousands
of integrated circuits were built onto a single silicon chip. The Intel 4004
chip, developed in 1971, located all the components of the computer from
the central processing unit and memory to input/output controls on a single
chip. In 1981, IBM introduced its first computer for the home user, and in
1984. Apple introduced the Macintosh. Microprocessors also moved out of
the realm of desktop computers and into many areas of life as more and more
everyday products began to use microprocessors. As these small computers
became more powerful, they could be linked together to form networks, which
eventually led to the development of the Internet. The fourth generation
computers also saw the development of GUIs, the mouse and handheld
devices. All the high-level languages like C, C++, Java, .Net, SQL, etc., are
used in this generation. IBM PC, Apple/Macintosh, SUPER BRAIN,
DEC 10, STAR 1000, PUP 11, CRAY-1 (Super Computer), CRAY-X-MP
(Super Computer), etc. are the examples of fourth-generation computers.

Microprocessor

The main features of the fourth generation are:

Microprocessors used as the main electronic component.
VLSI technology used, very cheap, portable, and reliable and very

small in size.
The speed, accuracy, and reliability of computers got improved.
The operating speed of these machines is measured in picoseconds.
They had larger storage capacity. Magnetic disk is the common source

of external storage in the Computers.
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A great development in the fields of networks and the concept of
internet was introduced.

Computers became easily available.

Fifth Generation of Computers

The period of fifth generation is 2010 to till
date. In the fifth generation, 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 the means and
method of making computers think like
human beings. AI includes robotics, playing
game, neural Networks, natural language
understanding, and development of expert
systems to make decisions in real-life situations.
Some examples of AI is Apple’s Siri on the Robot

iPhone and Microsoft’s Cortana on Windows 8 and Windows 10 computers.
The Google search engine also utilizes AI to process user searches.

The main features of the fifth generation are:
These computers have extra high processing speed.
They are have artificial intelligence.
They able to think and decide themselves.
They have the ability to communicate by using natural languages.
These computers use parallel processing.
These computers are used in intelligent robots.
These computers have the ability to solve the problem themselves.
They str able to recognize voice, images, and graphs.

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HP, Microsoft, and Apple have one very interesting thing in common – they
were all started in a garage.
IBM 5120 from 1980 was the heaviest desktop computer ever made.
2011 : Google releases the Chromebook, a laptop that runs the Google Chrome OS.
2015 : Apple releases the Apple Watch. Microsoft releases Windows 10.
2016 : The first reprogrammable quantum computer was created.

POINTS TO REMEMBER

A computer is an electronic device that processes data, converting it
into useful information.
Mechanical devices are used for the purpose of counting manually.
Abacus was the first counting device developed in China more than
3000 years ago.
Napier’s bones was developed by John Napier in 1617, a Scottish
Mathematician.
Slide Rule was an analog device invented by William Oughtred in 1620.
Pascaline, the first mechanical calculator, was invented by Blaise Pascal.
Stepped Reckoner, a calculating machine designed in 1671 and built in
1673 by the German mathematician-philosopher Gottfried Wilhelm Von
Leibniz.
Joseph Marie Jacquard invented an automatic weaving machine called
Jacquard Loom in 1801.
Charles Babbage is also known as the father of modern computer
science who invented Difference Engine in 1822 and Analytical Engine
in 1833.
Lady Augusta Ada Lovelace was the first computer programmer.

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The tabulating machine was an electrical counting machine invented by
Herman Hollerith in 1889.
Mark I was designed in 1937 by a Harvard graduate student, Howard H.
Aiken.
Atanasoff-Berry Computer – the ABC is considered the first electronic
digital computer and – the first machine to use vacuum tubes.
Electronic Numerical Integrator and Calculator, the  ENIAC  was the
first electronic computer used for general purposes, such as solving
numerical problems.
Electronic Delay Storage Automatic Calculator, EDSAC is an early British
computer considered to be the first stored program electronic computer.
UNIVAC was developed by J. Presper Eckert and John Mauchly.  
IBM 1401 a second generation mainframe computer was used in Nepal
in Census in 2028 B.S.
Computer generation is the classification of computers into different
groups according to their manufacturing date, and other hardware and
software technology used inside those computers.
Machine language is known as the first generation of computer
languages. It is made up of only two numbers.
AI is an emerging branch in computer science, which interprets the
means and method of making computers think like human beings.
Siri on the iPhone and Microsoft’s Cortana on Windows 8 and Windows
10 are the examples of AI.
Till date, there are five computer generations namely, the first, second,
third, fourth, and fifth generation.

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Exercise

1. Write very short answer to the following question.
a) Is computer an electronic or electrical device?
b) Who is considered the father of computer science?
c) Who developed slide rule?
d) Who is known as the first programmer?
e) What is the major component of the first-generation computer?
f) Which generation computer-supported GUI operating system?
g) Write one example of fourth-generation computer.

2. Write short answer to the following questions.
a) Why is Charles Babbage known as the father of computer science?
b) Draw the figure of Abacus showing its parts.
c) How are computer generations classified?
d) Define the term artificial intelligence.

3. State whether the following statements are true or false:
a) Abacus was the first electronic device.
b) Each bead in heaven has a value equal to 1 unit.
c) Slide Rule consists of two graduated scales one scale slides
or slips upon the other.
d) Slide Rule was an analog device invented by William Oughtred
in 1620.
e) Pacaline was earliest counting device.
f) Charles Babbage developed Difference Engine and
Analytical Engine.

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g) Joseph Marie Jacquard invented an automatic
weaving machine.

h) ABC is considered the first electronic digital computer.

i) IBM 1401 is the second generation minicomputer.

j) The computers of the second generation used transistor as
the basic components.

k) AI includes robotics, playing game, and Neural Networks.

4. Choose the best answer.

a) ..................was developed by the Chinese to perform simple calculations.

(i) Pascaline (ii) Abacus

(iii) Napier’s Bones (iv) Slide Rule

b) 8 BIT is equals with ..................

(i) 1 Nibble (ii) 2 bytes

(iii) 1 byte (iv) 1 Kilobyte

c) .................. is regarded as the first mechanical computing device.

(i) Abacus (ii) Napier’s Bones

(iii) Slide Rule (iv) Pascaline

d) Charles Babbage invented

(i) UNIVAC (ii) Mark-I

(iii) ABC (iv) Stepped Reckoner

e) Mark-I was made operational only in ..................

(i) 1937 (ii) 1924

(iii) 1944 (iv) 1984

f) .................. was the first general purpose electronic computer.

(i) ENIAC (ii) EDVAC

(iii) EDSAC (iv) UNIVAC

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5. Fill in the blanks :

a) ……………….was developed by the Chinese to perform simple
calculations.

b) Analytical Engine was designed in……………….
c) .................. is regarded as the first mechanical computing device.
d) Charles Babbage invented……………………
e) .................. was the first general purpose electronic computer.

6. Write the full forms of the following:

i) IBM ii) ASCC iii) ABC iv) ENIAC
vii) AI viii) IPO
v) EDSAC vi) UNIVAC xi) GUI xii) IC

ix) VLSI x) EDVAC

xiii) ULSI

7. Search three more words from the puzzle word below.

T RANS I S TORS
P S V B Y Y V K Y NM
X A UMD R B K Y Q X
R K S C VWD Z Q V T
D B N C A L RWP LW
MV V Z L B S Y YNX
NPDYJ I A I RTG
R L D G B Z NMB D B
D R Z P JMQ E D R L

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1 First counting device
2 Developed by Blaise Pascal
3 Second generation computers used
4 Fourth generation computers used

Activities

1. Take pictures from the magazine or from the Internet and make a chart on the
various generations of computers and paste pictures on the chart to make it
more attractive.

2. Search on the Internet and make a chart on the type of computers used in
making robots.

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Lesson

2

Introduction

Today, there are different types of computer having various features.
Computers are classified into various types. This classification is based
on their different attributes since the application area of computer is not
limited. Computers used in different sector are of different types. Here, we
discuss them according to the working principle. They are:

i. Analog computer ii. Digital computer iii. Hybrid computer

On the basis of working principle

Analog Computer Digital Computer Hybrid Computer

On the basis On basis
of purpose of size

Special Purpose General Purpose

Micro Mini Mainframe Super
computer computer Computer computer

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Analog Computer Analog Computer

Analog computer works on continuous signals.
Analog Computer simply measures physical
quantities (e.g. speedometer which displays
speed of vehicles, voltmeter, seismograph,
analog watch, pressure, temperature, length,
etc.) and converts them to numeric values. For
example, thermometer does not perform any
calculations but measures the temperature of
the body by comparing the relative expansion
of mercury. Analog Computer is mainly used
to control scientific equipment and engineering
purposes because it deals with quantities that
vary constantly. It is not hundred percentage
accurate.

Digital Computer

Digital computer works on digital data.
The general purpose digital computers
uses discrete data that can be in any
form like letter, numbers, symbols
and figures. These discrete data are
processed in the form of binary digits.
They are mostly used at home, in office,
and school. Special purpose digital
computers can be fixed permanently into
the machine. For example, processors Digital Computer

are installed in automobiles to control fuel, braking systems, etc. Digital
computers work on binary digits (0 – 1). All the operations in the digital
computer are performed in sequential or one operation at a time. Digital
computer can be classified on the basis of purpose and size. On the basis of
purpose, digital computers are classified into two types. They are:

i. Special Purpose Digital Computer

These types of digital computer are designed to perform a single specific
task. The program is loaded during the manufacturing time in this type

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of digital computer which cannot change by user or programmer. Digital
thermometer, digital washing machine, digital watch, digital television, self-
driven vehicle, etc. are the example of special purpose digital computers.

ii. General Purpose Digital Computer

The digital computers are designed to perform more than one work.
The user can load programs into the computer to perform different work.
Desktop computer, laptop computer, notebooks, smartphones and tablets
are the example of general purpose digital computers.

On the basis of size and processing speed, digital computers can be
further classified into four types. They are:

a) Super computer b) Mainframe computer
c) Mini computer d) Microcomputer

a) Super Computer

Super computers are the largest and most expensive digital computers.
Super computers contain several processors that work together to make it
most powerful and the fastest computer. They have a large memory capacity
and very high processing speed. They
can perform more than one trillion
calculations per second. They are
mostly used in forecast of weather
and global climates, biomedical
research, aircraft design, robots
design, military research and other
areas of science and technology.
Seismography, plasma and nuclear
research, encryption and decoding
of sensitive intelligence information
are also other application areas of Super Computer

such computers. Nowadays, most powerful super computer is Sunway
taihulight from National Super Computing Center, Wuxi, China. Super
computer Piz Daint, Tianhe-z, Titan, Seq voie, Cori, IBM Deep Blue, CRAY-
XMP, SX-3, CYBER 205, etc. are the popular examples of super computer.

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b) Mainframe Computer

Mainframe computer are less powerful
than super computer but more powerful, with
capacity of large storage and expensive than
minicomputer. These computers are multi-users
and multi-processors and support more than
100 of PC user can use it at a time because they
work on time sharing mode. These computers
are used as server on www (World Wide Web)
and also used in large organization such as bank,
telecommunication, examination department,
industries, airlines, etc. IBM is the major Mainframe Computer

manufacturer of mainframe computer. IBM 1401 mainframe computer
was brought first time to process census data in Nepal. ICL 2950/10, IBM
S/390, system 210 servers, and CDC (Control Data Cyber) 6600, are the
most popular examples of mainframe computer.

c) Minicomputer

Minicomputer is less powerful than mainframe computer but more
powerful and expensive than microcomputer. So, the capabilities of a
minicomputer are medium-sized. Minicomputer are usually designed to
serve multiple users simultaneously
(Parallel Processing) and used
in scientific research, banking
system, telephone switch, etc. These
computers work on multiprocessing
system. They are about more than
fifty of PC can be connected to
the network. PDI-1 was the first
minicomputer designed by DEC
(Digital Equipment Crop) company
in 1960. Time sharing, batch
processing, and online processing, Minicomputer

are the services provided by minicomputer. Digital Alpha, Sun Ultra,
IBM-System/3, and Honeywell 200, are the example of minicomputer.

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d) Micro Computer

Micro computer is also called PC (Personal Computer) or home
computer because it is single-user computer. Microprocessor is used as
its main component for processing unit (CPU). IBM-PC was the first micro
computer designed by IBM (International Business Machine) company.
Micro computer is used at home, in school, college, hospital, and offices for
carrying out various task. It supports many high level languages, computer
graphics, multimedia, and games. IBM PC, and Apple Mac are the example
of micro computer. It is further divided into the following categories:

Desktop Computer,
Laptop Computer,
Handheld Computer.

Desktop Computer Laptop Computer Handheld Computer

Mini Computers

Hybrid Computer

A hybrid computer is a type of computer that is
designed to provide the features and functions
present in both the digital and the analog
computers. A hybrid computer system offers a
much cost effective method to perform complex
simulations. These computers are the combined
form of analog and digital computers. These
computers are used in industrial application,
airplanes, ships, hospitals and in scientific
research center. They are used in hospital for ICU Hybrid Computer

(Intensive Care Unit), Electrocardiogram (ECG), Echocardiogram (ECHO),
Ultrasound machine, CT-Scan machine, etc.

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POINTS TO REMEMBER

Computers differ from each other on the basis of their purpose, capacity,
size, working principle, brand, etc.
Analog computers are special purpose computer which can measure
continuously changing data such as pressure, temperature length,
height, etc.
Digital computers are general purpose computer to solve problems by
discrete data.
IBM-PC was the first micro computer designed by IBM (International
Business Machine) company.
Desktop computer, laptop, and notebook, are the example of general
purpose digital computers.
Minicomputer is more powerful and expensive than micro computer but
less powerful and costly than mainframe computer.
Mainframe computer are more powerful, large storage, and expensive
than minicomputer but less powerful than super computer.
The computers commonly used today are all digital computers.
Super computers are the most powerful, expensive, and highest
processing speed than other computers.
The computer designed with combined feature of analog computer and
digital computer is called hybrid computer.
Supercomputers are used in weather forecasting and other scientific
computing.

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Exercise

1. Answer the following questions:

a) How are computers classified into different types? Explain.
b) Which computer performs a single task?
c) What are the differences between general purpose computers and special

purpose computers?
d) Define analog computer and state its uses.
e) What is a mainframe computer and what are its typical applications?
f) Define digital computer and list its different types.
g) What is the meaning of super computer? Write its application.
h) Write any four characteristics of micro computer.
i) What is hybrid computer? Where is it used?
j) Which was the first computer brought in Nepal?

2. Choose the best answer.:

a) Broadly, computers are of ................ purpose and ................ purpose

(i) specific, general (ii) specific, broad

(iii) precise, broad (iv) None of them

b) .................. computers work on continuous signals

(i) Analog (ii) Digital (iii) PS/2 (iv) None of them

c) ................ computers are the largest and most expensive digital computers.

(i) Mainframe (ii) Mini (iii) Super (iv) Apple

d) .................. is the example of mainframe computer.

(i) CYBER 205 (ii) IBM 3081 (iii) VAX (iv) IBM 9375

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e) Macintosh is the OS used in .................. computer.

(i) IBM (ii) mainframe (iii) super (iv) apple

f) .............. was mainframe computer brought first time to process census
data in Nepal.

i) IBM 1400 ii) IBM1401 iii) IBM1402

g) ……… computer are used in hospital for Ultra Sound.

i) Analog ii) Digital iii) Hybrid

h) Nowadays, the most powerful super commuter is Sunway taihulight from
.......................

i) India ii) Germany iii) China

3. State whether the following statements are true or false:

a) General purpose computers can carry out only a specific task.
b) An analog computer is the special purpose computer.
c) Analog computers work on binary digits.
d) Digital computer works on digital data.
e) Microcomputer is the most powerful and fastest computer.
f) Minicomputers are also multiuser computers.
g) Hybrid computers have the features of both analog and digital

computers.

4. Write the full form of following:

a) CPU b) PS/2 c) PC d) GUI
h) WWW
e) ECG f) ECHO g) IBM

5. Write the technical term for the following:
a) Computer that can carry out varieties of tasks.
b) A Computer that works on continuous signals.
c) A computer that is combined form of analog and digital computers.

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d) A digital computer works with microprocessor.
e) A computer that works on binary digits.

6. Match the following: Group ‘B’
Group ‘A’ a) Sunway Taihulight
b) used in hospital
i) Analog computer c) convert 0 or 1
ii) Digital computer d) measure continuously changing data
iii) Hybrid computer
iv) Super computer

Activities

1. Draw on a chart paper to show the classification of the computer-based on
working principle.

2. Prepare a PowerPoint presentation on the following topics:
The world’s smallest computer.
Use and purpose of hybrid and supercomputer in different sectors.
Search for information on the Internet and make a list of supercomputers
along with their use.

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Lesson

3

Introduction

A set of instructions written to instruct the computer to solve a particular
problem is called a program. A set of such program is known as software.
Computer software is a collection of computer programs and related data that
provides the instructions for telling a computer what to do and how to do it.
Software is an organized collection of programs, which is responsible for
controlling and managing the hardware components of a computer system
to perform specific tasks. It is non-touchable part of computer that brings
the computer hardware in function in order to perform tasks. Software
guides and controls the hardware to carry out the instructions to perform
the different operations in computer system. Microsoft Word, Microsoft
Excel, Adobe Page Maker, Adobe Photoshop, Linux, and Windows
7/8/10 are examples of computer software.

Different types of software

Computer software can be classified into two categories. They are:
i. System software
ii. Application software

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i) System software

System software is the collection of programs that control and
manage all the internal operation of the computer. It is designed to operate
the computer hardware, to provide basic functionality, and to provide a
platform for running application software. System software works as the
interface between hardware and the users. On the basis of functionality,
system software can be classified as follows:

a) Operating System Software
b) Language Processing Software
c) Utility Software

a) Operating System Software

An operating system (OS) software is
a collection manages computer hardware
resources and provides its users with an
interface. So, every computer needs to have
their own operating system, which takes care
of the effective and efficient utilization of all
the hardware and software components of the
computer. It is the first software that is loaded
into the computer memory (RAM). It installed Smart phones

in C: drive of hard disk. It is the master controller for all the internal
operations of the computer system. Every operating system performs the
basic functions such as managing resources, providing user interface, and
running application. The operating system in the computer works like an
interface between a user and application software. Some popular
operating systems are windows 7/ 8/ 10, Linux, UNIX, MS-DOS, Apple
macOS, Android kitkat, Android Marshmallow, and Apple’s iOS.

Operating System
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Some basic functions of operating system software are:
It provides easy interaction between user and computer.
It starts the computer and controls its entire functioning.
It controls and manages input / output devices.
It manages various types of memories such as primary, secondary,
cache, etc.
It interprets and executes the commands of application programs.
It provides platform to run other software programs.
It provides security to users’ jobs and files.
It allows users to share data and software among themselves.
It notifies the user about any fault that may occur in the computer.

On the basis of the user, operating system is divided into two types. They are:
i. Single User Operating System
ii. Multi User Operating System

i. Single User Operating System

As the name implies, Single-user-operating system is designed to
manage the computer so that one user can effectively do one thing at a time.
The Palm OS for Palm handheld computers is a good example of a modern
single-user, single-task operating system. This is the most common type of
OS used on a home computer, as well as on computers in offices, and other
work environments. There are two general types of single-user operating
system: single task and multitasking systems. MS-DOS, Windows 3X,
and Windows 95/97/98 are the examples of single user operating system.

ii. Multi User Operating System

A multi-user operating system allows multiple users to use the same
computer at the same time and different times. In other words, a multi-user
operating system is a computer operating system (OS) that allows multiple
users on different computers or terminals to access a single system with
one OS on it. These programs are often quite complicated and they must be
able to properly manage the necessary tasks required by the different users

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connected to it. Unix, Virtual Memory System (VMS) and mainframe OS are
the examples of multi-user operating system.

b) Language Processing Software

System software that converts various programming language into
machine level language is called language processor. So, language processor
converts high level language or assembly language into machine level
language and vice versa.

The three types of language processor are

a) Assembler b) Interpreter c) Compiler

a) Assembler

An assembler is a type of language processor which converts program
code written in assembly language into machine language. Mnemonic Code
is used for writing program in assembly language.

b) Interpreter

Interpreter is type of language processor which converts the program
written in high level language into machine level language line by line.
If there is any error on middle of program, the program is interrupted in
between. Some of the programming languages such as GWBASIC, QBASIC,
LISP, and LOGO, use interpreter language as translator.

c) Compiler

Compiler is a type of language translator that translates program
written in high level language into machine language in a single operation.
It reads all the statements of the program and translates the source code
into machine code (binary form). During the complication of the program,
if any error is found, it reports all the errors of the program along with
the line numbers at the end of complication. Some of the programming
languages such as C, C++,C#, Java, and FORTRAN use compiler as
language translator.

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Utility Software

Utility software is also called maintenance program. A set of programs that
perform task related to the service of computer software and hardware is
called utility software. The main objective of utility software is the smooth
functioning condition of computer system. The utility software performs
different tasks like formatting disk, taking backup of files, recovering of lost
data and file, removing viruses, partitioning of hard disk, defragmnentation
of hard disk. Some examples of utility software include Anti-virus ,
Archive, Backup, Cryptographic, Data compression, WinZip,
Register Cleaner, Disk defragmenters, and Disk partitions.

Antivirus WinRar WinZip Disk Defragmenter Cleaner

Utility Software

Application software

Application software is a type of computer software designed to solve specific
problem in specific time according to instruction provided by user. It is a
set of organized program developed to perform a specific data processing
jobs such as preparing documents, accounting ledgers, bills, playing music,
displaying result of exams, and manipulating graphics for the user. It can
manipulate text, numbers, graphics and a combination of these depending on
the work for which it was developed. Some examples of application software
are word processors, spreadsheets, database, accounting, web
browsers, payroll programs, communication programs, multimedia
programs, and graphics programs. There are two types of application
software. They are:

i) Packaged Software
ii) Customized or Tailored Software

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i. Packaged Software

Packaged software is a type of generalized set of application software
that allows the computer to perform specific task for different users. It is user
friendly, ready- made program designed to meet the common requirements
of a wide variety of users for particular type of work in more than one
environment. Some examples of the most commonly used packaged software
are word processing software, spreadsheet software, presentation
software, database software, graphics software, multimedia
software, and accounting software.

Microsoft office Package

Adobe Package Software

ii. Customized or Tailored Software

Customized or Tailored software is a type of specialized set of application
software designed to meet the specific requirements of an organization or
individual. It is developed on the demand of only single organization or user
to satisfy their needs and such software that may not be useful for other
organizations or users. Some examples of customized software are school
management software, telephone bill processing software, air
ticket reservation software, payroll software, SEE result processing
software, and hospital management software.

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OSS (Open Source Software)

Open source software is freely available software and source code is also
available free of cost. So, open source software is called free software. In open
source software, the users modify source code according to their requirement.
Open source software was started by Richard Stallman in 1983.

Open Source Softwares

Features of Open Source Software

The source code is available to modify and redistribute to others.
Open Source Software is free software. So, some money can be donated

to open source software developer group.
One cannot sell them to individual or organization.

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POINTS TO REMEMBER

The set of instruction or program written by using programing language
to solve a problem is called computer software.
The software that manages, controls and supports computer system is
called system software.
Operating system software is the system software that manages and
controls overall operation of computer.
Language processor converts high level language or assembly language
into machine level language and vice versa.
An assembler is a type of language processor which converts program
code written in assembly language into machine language.
The main objective of utility software is the smooth functioning condition
of computer system.
The application software is used to type e-mail, photo editing,
presentation, listening to music, engineering design, video, and
producing bills.
Open source software is freely available software and source code is
also available no cost at all.

Exercise

1. Write very short answer of the following question.
a) Which software manages hardware resources?
b) Give one example of single user operating system.
c) Which language is used Mnemonic Code?
d) Which type of program is called maintenance program?

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2. Write short answer of the following questions:
a) What is software? Write its types.
b) What is system software? List its types.
c) What is an operating system? Write of its any two functions.
d) Explain the types of operating system with examples.
e) Define utility software with any four examples.
f) Differentiate between interpreter and compiler.
g) What is application software? Explain its types.
h) Give the special features of packaged software.
i) Define language processor with its types.

3. State whether the following statements are true or false:
a) A set of command id called software.
b) Android Marshmallow is operating software.
c) System software provides environment to run application
software.
d) A single-user operating system allows multiple users to use
the same computer at the same time
e) Utility software takes care and maintains a computer.
f) Compiler translates program written in assembly language into
high level language.
g) Tailored software is specialized software designed to meet
the specific requirements of an organization.
h) Open source software is not freely available software and
source code.

4. Fill in the blanks:
a) ...................... is a collection of computer programs.
b) ............ controls and manages all the internal operations of the computer.

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c) Utility software takes …………..….. and ………….…. a computer.

d) A computer system understands only ………………… language.

e) …………..… is a language processor.

f) A software program designed to meet the specific requirements of an
organization or individual is known as ……………… software.

5. Write the technical terms:

a) A set of program that controls and manages all the internal operations of
a computer.

b) An operating system that allows multiple users to use the same computer
at the same time.

c) A language translator that converts program written in high level language
into machine language line by line.

d) A computer program that allows other programs to interact with
a hardware device.

e) Software that is designed for general user for common purpose.

6. Write the full form of:

i) MVS ii) GUI iii) OS
vi) GPL
iv) MS DOS v) OSS

7. Match the following: Group ‘B’
Group ‘A’

i) Customized software a) Android Marshmallow

ii) Package software b) Bank software

iii) Operating system c) Norton antivirus

iv) Utility software d) MS Office package

e) IBM

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Activities

1. Find out what are the hardware and software details of your computer system
are at home or in your computer lab.

2. Complete the crossword puzzle with the help of the given clues.

12
3

4

5

ACROSS
3 Language processor which converts line by line into machine level

language
4 Language processor which converts high level language into machine

level language
5 Collection of programs

DOWN
1 Character user interface OS
2 Utility software

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Lesson

4

Introduction

In past, the concept of number system evolved when human used their
fingers, sticks, pebbles, knots of rope, and different symbols for counting
and simple addition or subtraction. In course of time, they used calculating
device and then computers for calculation.
At present, we use decimal number system that has digits from 0 to 9.
However, computers only understand 0s and 1s. Programming using 0s and
1s is tedious job. It is really difficult to remember all 0s and 1s. We can use
the decimal numbers, the alphabets, and special characters like +, -, *, /, ?, #,
!, &, etc. for programing the computers. Inside the computer, these decimal
numbers, alphabets, and the special characters are converted into 0s and 1s
so that the computer can understand what we instruct it to do.
The combination of digits or symbols used to express different quantities as
the basis for doing different calculations is called number system.

Types of Number System

Different types of number system developed today. Number system is
differentiated by its base or radix. The base or radix is defined as the total
number of digits or symbols available in the number system. So, the number
system is divided into four types on the basis of base or radix. They are:
i. Binary Number System

0, 1 (i.e. base or radix 2 system)
ii. Octal Number System

0,1,2,3,4,5,6,7 (i.e. base or radix 8 system)
iii. Decimal Number System

0,1,2,3,4,5,6,7,8,9 (i.e. base or radix 10 system)

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iv. Hexadecimal Number System
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E and F (i.e. base or radix 16 system)
Number Systems

Binary Octal Decimal Hexadecimal

Digits 0, 1 Digits 0 to 7 Digits 0 to 9 Digits 0 to 9 and A to F.
Base 2 Base 8 Base 10 Base 10

i. Binary Number System

The base or radix of the binary number system is 2. Digital computers
use the binary number system, which has two digits 0 and 1. A binary
digit (either a 0 or 1) is called a bit. Information is represented in digital
computers in groups of bits. By using various coding techniques, groups
of bits can be made to represent not only binary number but also other
discrete symbols, such as decimal digits or letters of the alphabets, special
characters like *, &, $, #, !, +, -, ?, etc. By the use of binary number and by
various coding techniques, the groups of bits are used to develop complete
set of instruction for performing various computations. The string of digits
101101 is interpreted to represent the quantity.

1 x 25 + 0 x 24 + 1 x 23 + 1 x 22 + 0 x 21 + 1 x 20
= 32 +0+ 8 + 4 + 0+1
= 45
Thus all the decimal numbers can be written in binary format.

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0 or 1 = 1 bit

4 bits = 1 nibble

8 bits = 1 byte

ii. Octal Number System

The number system that is used in computer system to hold any data
on byte is the octal number system. Octal number system has base 8 as it
uses 8 digits from 0 to 7. For example (170) , (650) , (3200) , etc.
88 8

iii. Decimal Number System

Hindu philosophers developed decimal number system. The number
system that we use in our daily life is the decimal number system. Decimal
number system has base or radix is 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 678 consists of the digit 8 in the units position, 7 in the tens
position and 6 in the hundreds position. Its value can be written as

(678) = (6×100) + (7×10) + (8×1)
10 = (6×102) + (7×101) + (8×100)
= 600+70+8
= 678

iii. Hexadecimal Number System

The number system that is used in computer system to hold any data
is the hexadecimal number system. Hexadecimal number system has base
16 as it uses 16 digits (10 digits and 6 letters, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B,
C, D, E, and F). Letters represent the numbers starting from 10 that is A =
10, B = 11, C = 12, D = 13, E = 14 and F = 15. For example (7A2) , (1AC) ,
(56B) , (B0D) , etc. 16 16

16 16

49 Approved by Curriculum Development Centre, Sanothimi, Bhaktapur

Vedanta Let’s Log in Computer Science | Book 8

Number system Conversion

The people use mainly decimal number system. Computer uses binary
number system. We can not understand binary, octal, and hexadecimal
number system in the same way computers can not understand decimal
number system. So there are different methods to convert one number
system to another as follows:

Decimal to Binary

A positive decimal integer can be converted to binary through successive
division by 2 till the quotient becomes zero and sequential collection of
remainder on the last-come-first basis (i.e. bottom to top).

Convert (66) into Binary
10

Step 1 : Divide the given decimal number and write down the
remainder.

Step 2 : Divide quotient by 2 and again write down the remainder.
Step 3 : Repeat the process until quotient becomes zero.
Step 4 : Write the remainders bottom to top.
Example 1:
i. (66) = (?)

10 2

2 66 Remainder
2 33 0
2 16 1
28 0
24 0
22 0

10

Hence, (66) = (1000010)
10 2

50Approved by Curriculum Development Centre, Sanothimi, Bhaktapur


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