Green-Computer-Book-8

Approved by Government of Nepal, Ministry of Education, Curriculum
Development Centre, Sanothimi, Bhaktapur as an additional material

Green

Computer

8

Editor
Reg Bahadur Bhandari

Author
Prabhu Prasad Sah

Lalitpur, Nepal, Tel: 977-1-5529899
E-mail: [email protected]
www.greenbooks.com.np

Green

Computer

9

Publisher: Green Books

Copyright: Author (2074 BS)

Edition
First : B.S. 2074 (2017 AD)
Reprint : B.S. 2075 (2018 AD)
Revised : B.S. 2076 (2019 AD)
Revised : B.S. 2077 (2020 AD)

Layout
The Focus Computer
[email protected]

Printed in Nepal

Preface

Computer has become an integral part of human life.
Computer is the greatest invention man has ever made.
There are hardly any fields on this earth where computers
have not been used. So, it has become a necessity for every
individual to be computer literate. So, computer studies
has been incorporated in curriculum in our country too.

Green Computer series has been designed with a vision
that it would help students address their general needs of
word-processing and simple database management and
also to orient their minds to IT to be able to contribute in
the future.

This series can be a great tutorial for novices who are really
interested to learn the basics of computer. All our efforts
have been put forth to make this series descriptive in order
to make the contents understandable and communicate
instructions easily. We have tried to use simple English for
the convenience and easy understanding of instructions
both in theory as well as in practical lessons. Varieties of
theory based exercises and relevant lab sessions have been
included in order to give concepts on different topics and
evaluate students’ understanding.

We would like to express our sincere gratitude to Green
Books, Focus Computer Team, colleagues, friends and well
wishers without whom, this series wouldn’t have taken is
shape.

We believe that this series is free of errors, yet there can
be some slips. So, we would like to welcome from all our
readers students, teachers, individuals and institutions
valuable suggestions and feedback for revision in the
upcoming editions.

Finally, we are thankful to our parents for making us
capable of contributing a little to the society and the
country.

Author

Content

1. History of Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Computer Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3. Types of Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4. Computer Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5. Types of Operating System . . . . . . . . . . . . . . . . . . . . . . . . 34
6. Number System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7. Advanced Features of Microsoft Word . . . . . . . . . . . . . . 50
8. More on Spreadsheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
9. Advance Features of PowerPoint . . . . . . . . . . . . . . . . . . 106
10. Concept of ICT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
11. Cyber Law and Ethics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
12. Computer Virus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
13. Data Communication and Computer Network . . . . . . 138
14. Introduction to Internet and E-mail . . . . . . . . . . . . . . . . 151
15. Hyper Text Markup Language(HTML) . . . . . . . . . . . . . 161
16. Multimedia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
17. Graphics Application (Adobe Photoshop) . . . . . . . . . . . 219
18. Program Development Life Cycle (PDLC) . . . . . . . . . . . 236
19. Algorithm and Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . 241
20. Fundamental of QBASIC . . . . . . . . . . . . . . . . . . . . . . . . . 249
21. QBASIC Statements and Library Functions . . . . . . . . . 263
22. Looping in Qbasic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

1 History of Computer

Introduction

Humans have always needed to perform arithmetic operation like counting
and adding. During the pre-historic period, they counted either on their
fingers or by scratching marks on the bones and then with the help of stones,
pebbles and beads. The word ‘computing’ means ‘an act of calculating’. The
evolution of computers has passed through a number of stages before reaching
the present state of development. In fact, the history of computers comprises
a gradual development from a simple abacus to the electronic computers we
use today.

a. Abacus

The abacus was created by the Chinese
about 3000 years ago as the first mechanical
aid to do calculations. Calculations are
performed by manipulating the beads. It is
a rectangular box, divided into two parts
by the mid bar. The upper part is called
“heaven” which consists of two beads and each bead is equal to five and the
lower part is called “earth” and consists of five beads and each bead is equal
to one.

b. Napier’s Bone

Napier's Bone was invented by John Napier in 1614 AD. He
was a Scottish mathematician born in 1550 and died in 1617
AD. Multiplication tables were inscribed on strips of wood
or bone. It was possible to perform calculations with two
numbers. It is mainly used for multiplication.

GREEN Computer Book-8 5

John Napier of Merchiston also signed as Neper, Nepair;
nicknamed Marvellous Merchiston) was a Scottish
landowner known as a mathematician, physicist, and
astronomer. John Napier is best known as the inventor of
logarithms. He also invented the so-called "Napier's bones"
and made common the use of the decimal point in arithmetic
and mathematics.

c. Slide Rule

Slide Rule was invented by William Oughtred, an English mathematician in
1620. It is an analog device that uses the principle of logarithms. It can perform
simple multiplication and division problems. It consists of two graduated
scales, devised in such a way that suitable alignment of one against other
makes it possible to obtain products, quotients, etc.

William Oughtred was an English mathematician and Anglican minister.
After John Napier invented logarithms and Edmund Gunter created the
logarithmic scales (lines, or rules) upon which slide rules are based, it was
Oughtred who first used two such scales sliding by one another to perform
direct multiplication and division; and he is credited as the inventor of the
slide rule in 1622. Oughtred also introduced the "×" symbol for multiplication
as well as the abbreviations "sin" and "cos" for the sine and cosine functions.

d. Pascaline

Pascaline was developed by Blaise Pascal
in 1642 to help his father in his tax works.
It contains eight dials, gears and wheels.
It was capable of performing additions
and subtractions up to 8 digits. It could
add and subtract by the movement of
wheels and could not be used for division
and multiplication.

6 GREEN Computer Book-8

In 1642, while still a teenager, Blaise Pascal started some
pioneering work on calculating machines. After three years
of effort and 50 prototypes, he built 20 finished machines
(called Pascal's calculators and later Pascalines) over
the following 10 years, of the first two inventors of the
mechanical calculator establishing him as one.

e. Stepped Reckoner

Stepped Reckoner was developed
by Gottfried Wilhelm Von Leibniz, a
German mathematician and philosopher
in 1694. It could evaluate square roots
by a series of stepped additions. The
centerpiece of this machine is its stepped
drum gear design. It could perform all four of the basic arithmetic functions –
addition, subtraction, multiplication and division.

Gottfried Wilhelm (von) Leibniz was a German polymath
and philosopher who developed differential and integral
calculus. Leibniz's notation has been widely used ever
since it was published. While working on adding automatic
multiplication and division to Pascal's calculator, he was the
first to describe a pinwheel calculator in 1685 and invented
the Leibniz wheel, used in the arithmometer, the first mass-
produced mechanical calculator. He also refined the binary
number system, which is the foundation of virtually all
digital computers.

f. Difference Engine

Difference Engine was designed by Charles
Babbage, an English mathematician, in 1822. It
could solve equations. This project could not be
completed due to lack of funds. It was housed in
the Science Museum, London and is still in perfect
working order.

GREEN Computer Book-8 7

g. Analytical Engine

Analytical Engine was developed by Charles
Babbage in 1833. It had a ‘store’ for storing
data and intermediate results. It had an output
device to produce printed results. It had a unit
for calculation called ‘mill’. All the modern
computers are based on the working principle
of analytical engine (input-process-output).

Charles Babbage is known as the ‘Father of Modern
Computer’ as his invention of Analytical Engine had more
of the characteristics of modern computers.

h. Hollerith Tabulator

Tabulator was developed by an
American, Dr. Herman Hollerith, in
1887. It used punch cards for input,
output and instructions. This machine
was used by American Department of
Census to compile the 1890 census.
• In 1890, punch cards were used

by Herman Hollerith to automate
Census
• Concept of programming the
machine to perform different tasks with punch cards was from Babbage.
• Punch cards based on Joseph Marie Jacquard’s device to automate weaving
looms.
• In 1896, he founded the tabulating machine company which was renamed
as IBM (International Business Machine).

8 GREEN Computer Book-8

Lady Augusta Ada Lovelace

An English mathematician (daughter of English Poet
Lord Byron) carried forward the work of Charles
Babbage. She developed programs for performing
mathematical calculation on the Analytical Engine.

She was the first computer programmer. One
programming language ‘Ada’ was named after her.

John Von Neumann

He was the doctorate in mathematics from
the University of Budapest on set theory. He
designed the EDVAC with team of J.P. Eckert
and J.W. Mauchly. He introduced the concept
of having a stored program in memory in 1945.
This concept led to the beginning of the first
generation of computers.

Electro-Mechanical Computers

Mark-I 9

• Mark - I was designed by Howard Aiken,
a Harvard engineer in 1937. It was 51 ft.
long, 8 ft. tall and 3 ft. wide having 18000
vacuum tubes. It was the first automatic
electromechanical computer. It used
instructions stored in paper tapes and
punch cards. It consisted of 7 lakh 50 thousand parts.

GREEN Computer Book-8

ABC (Atanasoff-Berry Computer)

• ABC was the first electromechanical digital computer. Built in 1937-1942 at
Iowa State University by John V. Atanasoff and Clifford Berry.

• It introduced the ideas of binary arithmetic and logic circuit.

• It used punch cards as secondary storage.

Inventor's birth date and death date

Inventor's name Birth date Death date
4-April 1617
John Napier 1550 30 June 1660
1642
William Oughtred 5 March 1574 14 November 1716

Blaise Pascal 1623 1871
1926
Gottfried Wilhelm Von 1 July 1646 1852
Leibniz 1957
1973
Charles Babbage 1792

Herman Hollerith 1869

Lady Augusta Ada 1816

John Von Neumann 1903

Howard Aiken 1900

Electronic Computers

ENIAC (Electronic Numerical Integrator and Calculator)
• ENIAC was designed by Dr. John

W. Mauchly and Dr. J. P. Eckert,
completed in 1946.

• It was built from 18,000 vacuum
tubes and 70,000 resistors. Power
consumption – 50,00,000 Kilowatt
and floor space – 1,800 square feet.

• It could add two numbers in 200
microseconds and multiply two
numbers in 2800 microseconds.

EDSAC (Electronic Delay Storage Automatic Computer)
• EDSAC was designed by Maurice Wilkes at Cambridge University,

10 GREEN Computer Book-8

mathematical laboratory in 1947.
• It was the first operational stored-program computer.
• It contained 3000 vacuum tubes and operated with 30 kilowatt of power.
• It used a mercury delay line storage system.

EDVAC (Electronic Discrete Variable Automatic Computer)
• Designed by J. Mauchly and J.P. Eckert at Pennsylvania University and

was completed in 1950.
• It included a stored-program, a central processor and a memory for both

data and programs.

UNIVAC (Universal Automatic Computer)
• Produced by Universal Accounting Company

and set up by John Mauchly and J.P. Eckert in
1951.
• It consisted of magnetic tape for data input and
output.
• It was the first general-purpose electronic digital
computer designed for commercial use.

History of Computer in Nepal

• The history of computer in Nepal is relatively new, started from 2018.

• In 2018 BS an electronic calculator called "Facit" was used for census.

• In 2028 BS (1972 AD) census, IBM 1401 a second generation mainframe
computer was used.

• In 2031 BS (1975 AD), a center for Electronic Data Processing, later renamed
as National Computer Center (NCC),was established for national data
processing and computer training.

• In 2038 BS ( 1982 AD), ICL 2950/10 a second generation mainframe
computer was used for census.

• Now-a-days probably each and every institution, business organization,
communication center, ticket counter, etc are using computers in Nepal.

GREEN Computer Book-8 11

POINTS TO REMEMBER

1. The abacus was created by the Chinese about 3000 years ago as the first
mechanical aid to calculations.

2. Napier’s Bone can perform calculations with two numbers.
3. MARK-I is the first electromechanical computer.
4. The vacuum tube was used in the first generation computers.
5. ABC (Atanasoff-Berry Computer) is the first electromechanical digital

computer.
6. William Oughtred also introduced the "×" symbol for multiplication as

well as the abbreviations "sin" and "cos" for the sine and cosine functions.
7. Pascaline was capable of performing additions and subtractions up to 8

digits.
8. UNIVAC consisted of magnetic tape for data input and output.
9. EDSAC used a mercury delay line storage system.
10. Lady Augusta Ada developed programs for performing mathematical

calculation on the Analytical Engine.

Exercise

1. Answer the following questions:

a. What is an abacus? Draw a neat and clean figure of an abacus.
b. Why is Charles Babbage called the Father of Computer?
c. Who is known as the first computer programmer? Why?
d. Who developed Napier’s Bone? When was it developed?
e. What do you know about Hollerith Tabulating machine?
f. Who developed Pascaline and when? What type of calculation could

it perform?
g. Give a brief history of computer in Nepal?

2. Write down the Full Forms of the following:

a. ABC b. UNIVAC c. EDVAC
d. EDSAC e. ENIAC

12 GREEN Computer Book-8

3. Write short notes. c. Mark-I d. Analytical Engine
a. ABC computer b. ENIAC

4. Match the following: John V. Atanasoff and Clifford
a. MARK-I Berry.

b. UNIVAC Father of Ccomputer
c. Charles Babbage
d. ABC Howard Aiken
e. J. Mauchly and J.P. Eckert
EDVAC

first general-purpose electronic
digital computer

5. State whether the following statements are ‘True’ or ‘False’.

a. The abacus is the first electronic computer.
b. It was the first general-purpose electronic digital computer designed

for commercial use.
c. EDSAC used a mercury delay line storage system.
d. Difference Engine was developed by Howard Aiken.
e. Napier’s Bone can perform calculations with two numbers.

6. Who developed the following devices and when?

Devices Developed by Date of Invention
ENIAC
EDSAC
EDVAC
UNIVAC
ABC
MARK-I
ANALYTICAL ENGINE
PASCALINE
STEPPED RECKONER
SLIDE RULE
NAPIER’S BONE

GREEN Computer Book-8 13

2 Computer Generation

Introduction

Initially, the term generation was used to distinguish between varying hardware
technologies. But nowadays, generation includes both hardware and software,
which together make up an entire computer system.
The evolution of modern digital computing took place in five distinct phases
known as computer generations, which are classified on the basis of their
speed, capacity, reliability, components used, etc.

First Generation Computers (1945-1956)

Vacuum Tube: It was used as the main
component for memory and circuitry for
CPU. It was very slow, large in size, and
consumed a lot of electrical power. The
operating speed was measured in terms
of milliseconds. Storage capacity was too
small; only 1 to 4Kb. They used machine
level programming language. Punch cards,
paper tape, and magnetic tape were used as
input and output devices. Batch processing
operating systems were used.

Some of the first Generation Computers are:
Mark – I, ENIAC, EDVAC, EDSAC, UNIVAC, etc.

14 GREEN Computer Book-8

The vacuum tube was invented by Lee
De Forest in 1907. It is a set of metal
electrodes and grids contained in a glass
or metal tube. It was formerly used for
amplification and switching in electronic
circuits, now used in CRT (Cathode Ray
Tube).

Second Generation Computers (1956 – 1963)

Transistors replaced vacuum
tubes. One transistor consist
of thousand vaccum tubes.
The size of computer
was reduced. It became
faster and more reliable
than the first generation
computers. The operating
speed was measured in
terms of microseconds.
Magnetic tapes were used
as secondary storage media. High-level programming languages were
also being developed at this time, such as early versions of COBOL and
FORTRAN.

Some of the second Generation Computers are:

LEO Mark III, ATLAC, UNIVAC I, ICL 1901, etc.

Transistor is short form of transfer resistor. It is a solid state
semi-conductor device which can be used for amplification,
switching, voltage stabilization, signal modulation, etc. It
transfers signals from a low resistance to high resistance.
It was invented in 1947 by three Bell Lab scientists John
Bardeen, Walter Brattain, and William Shockley. It was used
in the second generation computers as major components.

GREEN Computer Book-8 15

Third Generation Computers (1964-1971)

IC (Integrated Circuits) made the
computers smaller, more efficient and
more reliable than the previous generation
of computers. The operating speed was
measured in terms of nanoseconds, so
that computers became so fast. In the
beginning magnetic core memories
were used. Later they were replaced by
semiconductor memories (RAM & ROM)
There were input and output devices
such as keyboard and monitors instead
of punch cards in this generation. Due to
the use of input and output devices, it was so easy in operation. High level
languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL -68
etc.) were used during this generation.

Some of the third Generation Computers are:

IBM 360 Series, ICL 1900 Series, VAX 1/780, etc.

An IC is a circuit consisting of a large number of
electronic components placed on a single silicon
chip by a photolithographic process. Jack Kilby
invented it in 1958. IC is used for a variety of
devices, including microprocessor, audio and
video equipment and automobiles.

Fourth Generation Computers – (1971 – Present)

Microprocessor/ Large Scale Integrated
Circuit (LSIC) and Very Large Scale Integrated
Circuit (VLSIC) was the main component
that included 5000 transistors. Due to the use
of LSIC and VLSIC size was greatly reduced.

The operating speed increased beyond
picoseconds. Many sophisticated programs
for special application were available.
Magnetic and optical storage devices with

16 GREEN Computer Book-8

capacity more than 500GB were used as secondary memory. All the Higher
level languages like C and C++, DBASE, etc. were used in this generation.

Some of the fourth Generation Computers are:
Pentium I/II/III/IV, HP 3033, APPLE II, etc.

The microprocessor is a computer
processor built onto a single piece
of silicon, known as a wafer or
chip. The first microprocessor is
Intel 4004 developed by American
Intel Corporation in 1971.

Fifth Generation Computers – (Present and Beyond)

Major components – ULSI (Ultra
Large Scale Integration). The concept
of AI (Artificial Intelligence) has
been introduced which enables the
computers to take decisions on their
own. Bio chips and Gallium Arsenide
(Ga As) are used as memory devices.
Extremely high-speed parallel
processing capability. Large use of
natural language processing and user
friendly. Programming computers for
robotics to see, hear and react to other
sensory stimuli. More user friendly
interfaces with multimedia features.
Portable note book computers
introduced.

Some of the Fifth Generation Computer Projects are:
ICOT program in Japan, MCC project in the USA, etc.

GREEN Computer Book-8 17

The future device that will be used in
the 5th generation computers, made of
large organic molecules and a genetically
engineered protein is called “Biochip”.

POINTS TO REMEMBER
1. The microprocessor replaced IC in the fourth generation.
2. An IC is a circuit consisting of a large number of electronic components

placed on a single silicon chip.
3. The computer generations are classified into five different categories

as per the technological advancements and major components used for
processing over different periods of time.
4. Transistor was invented in 1947 at Bell Labs by Robert Noyce and Jack
Kilby.
5. The Third Generation of Computers used IC as their major components
which could do the functions of millions of transistors.
6. ICs are made up of silicon, a semiconductor material.
7. The Fifth Generation of Computers are believed to have the features
like human brains which is known as AI (Artificial Intelligence).

Exercise

1. Answer the following questions:

a. What is Abacus? Draw a neat and clean figure of Abacus.
b. What is computer generation?
c. What are the features of the fifth generation of computers?
d. Write the differences between the first generation and the second

generation of computers.
e. Who developed IC and when?
f. What are the features of the fourth generation computers?

18 GREEN Computer Book-8

2. Write down the Full Forms of the following:

a. IC b. AI c. ULSI
d. LSIC e. Ga As

3. State whether the following statements are ‘True’ or ‘False’.

a. The IC was used in the first generation computers.
b. A transistor is a circuit consisting of a large number of electronic

components.
c. Our PC is the fourth generation computer.
d. The first generation computers were very small.
e. If replaced VLSIC in fourth generation.
f. Intel 4004 was developed by American Intel Corporation 1971.
g. ICL 1900 series was developed in second generation.
h. Microprocessor is a computer processor build onto a single piece of

silicon.

4. Match the following words: Jack Kilby
a. VLSIC John Bardeen, Walter Brattain, and
b. Vacuum tube William Shockley
fourth generation computer
c. Transistor Lee De Forest
d. Biochip Fifth generation
e. IC

5. Fill up the table with the appropriate information.

Generations Period Main component Computers developed
1st generation
2nd generation
3rd generation
4th generation
5th generation

GREEN Computer Book-8 19

3 Types of Computer

Introduction

The computer on the desk in your computer lab is a microcomputer. It is a
small, powerful piece of equipment. Even so, the power of a microcomputer is
not enough for most large organizations. Computers can be used in different
sectors like school, hospital, offices, resource centers, music, movies, etc.
Computers used in different sectors may not be of the same types. They may
differ in processing speed, storage capacity, size and nature of tasks that they
can perform. A computer can be as big as an entire room or as small as a
microcontroller found in mobiles and embedded systems.
Computers may be special purpose computer and general purpose computer.
Special purpose computers are designed to perform specific tasks and general
purpose computers are versatile, designed to perform various tasks.
Computers can be divided into different categories on the basis of size and
work.

On the basis of work

There are three types of computers on the basis of work. They are:
1. Analog computer
2. Digital computer
3. Hybrid computer

1. Analog computer:
An analog computer is a computing

device that works on continuous range
of values. It gives approximate results
since it deals with quantities that change
20 GREEN Computer Book-8

continuously. It generally deals with physical variables such as voltage,
pressure, temperature, speed, etc. ECG (Electro Cardio Graph) is an
example of an analog computer.

2. Digital computer:
Our PC is a digital computer which

operates on discrete data. Its
operation is based on binary system.
i.e. 0 and 1 digits. Digital Computers
can give the results with more
accuracy and at a faster pcae. They
are able to save data for future use
also.

3. Hybrid computer:
A hybrid computing system is a

combination of desirable features
of analog and digital computers.
It is mostly used for automated
and complex operations such as
ultra sound and equipment of ICU
(Intensive Core Unit) in hospitals.
(ECG) Electrocardiogram, Halter
Monitoring machine, etc. are examples
of hybrid computer.

On the basis of size:

There are four types of computers on the basis of size and speed and these all
are digital computers.
1. Micro computers
2. Mini computers
3. Mainframe computers
4. Super computers

GREEN Computer Book-8 21

Workstations are also single-user computers
like PC but are typically linked together to
form a local-area network, although they
can also be used as stand-alone systems.
Workstations generally come with a large,
high-resolution graphics screen, large
amount of RAM, inbuilt network support,
and a graphical user interface.

1. Micro computers:

The invention of the microprocessor (single chip CPU) gave birth to micro
computers. Official and household computers are micro computers. Micro
computers are also known as personal computers. They are small in size and
light in weight. Some of the micro computers can be held on the palm and on
the lap. They are called palmtop and laptop computers. Personal computers
are categorized as:

Desktop computers
Desktop computers are designed for use at a desk or
table. They are typically larger and more powerful
than other types of personal computers.

Tower PCs:
Tower PCS are those microcomputers in which the
case sits as a "tower," often on the floor beside a
desk, thus freeing up the desk surface space.

Laptops and Notebooks
Laptops and Notebooks are also called notebook
computers. They are light weight portable computers
with built-in monitor, keyboard, hard-disk drive,
battery, and AC adapter that can be plugged into an
electrical outlet. You can put a laptop on your lap and
work.

22 GREEN Computer Book-8

Personal digital assistants (PDAs)

PDAs are also called handheld computers or
palmtops combine personal organization tools-
schedule planners, address books, to-do lists, etc.
Some are able to send e-mails and faxes. Some
PDAs have touch-sensitive screens. Some also
connect to desktop computers for sending or
receiving information.

Tablet PCs

Tablet PCs are mobile PCs that combine features of
laptops and handheld computers. Like laptops, they're
powerful and have a built-in screen. Like handheld
computers, they allow you to write notes or draw
pictures on the screen, usually with a tablet pen instead
of a stylus. They can also convert your handwriting into
typed text. Some Tablet PCs are “convertibles” with a screen that swivels and
unfolds to reveal a keyboard underneath.

Smart phones

Smart phones are mobile phones that have some of the same
capabilities as a computer. You can use a smart phone to
make telephone calls, access the Internet, organize contact
information, send e-mails and text messages, play games,
and take pictures. Smart phones usually have a virtual
keyboard and a large screen.

2. Mini computers:

Mini computers are the medium sized
computers which are larger than micro
computers and smaller than mainframe
computers. They have larger storage
capacity and higher speed than micro
computers. Minicomputers may contain
one or more processors, support
multiprocessing and tasking that can
support up to 200 users simultaneously,
and are generally resilient to high workloads. Some of the Mini Computers
are: IBM AS/400, IBM SYSTEM 360, HP 3000, PRIME 9755.

GREEN Computer Book-8 23

3. Mainframe computers:

A very large and expensive computer
capable of supporting hundreds, or even
thousands, of users simultaneously is
mainframe computers. Their performance
speed and storage capacity is higher than
the mini computers. Some of the obvious
customers are banks, airlines and railway
reservation systems, aerospace companies
doing complex aircraft design, etc. Some
of the Mainframe Computers are - IBM S/390, Amdahl 580, Control Data
Cyber 176.

4. Super Computers:

Super computer are the most powerful
and expensive computers. They are
very high speed computers. They are
employed for specialized applications
that require immense amounts of
mathematical calculations. They are used
in the areas like weather forecasting,
automobile designing, aircraft launching,
bomb testing, etc. Some of the super
computers are: Cray-1, Cray-2, Control Data Cyber 205, ETA, etc.

POINTS TO REMEMBER

1. Micro computers are also known as personal computers.
2. An analog computer is a computing device that works on continuous

range of values.
3. Our PC is a digital computer which operates on discrete data.
4. A hybrid computer is the fusion of analog and digital computers.
5. A super computer is the fastest computer used in scientific research.
6. Minicomputers may contain one or more processors, support

multiprocessing and tasking that can support up to 200 users
simultaneously.
7. A laptop is also called notebook computer.
8. The computers on the basis of size are digital computers.

24 GREEN Computer Book-8

Exercise

1. Answer the following questions:
a. Write any two differences between analog computers and digital
computers.

b. What do you mean by a hybrid computer? Give some examples.

c. What is a super computer? Where is it used?

d. List out the computers on the basis of size.

e. What is a micro computer? List out the types of microcomputers.

f. Write differences between minicomputers and mainframe computers.

2. Write short notes on : b. Tablet
a. Desktop d. Workstation
c. PDA

3. State whether these statements are 'True' or 'False':
a. Personal computers are also called digital computers.
b. A desktop computer can be put into the lap and work.
c. Smart phones are mobile phones that have some of the same
capabilities as a computer.
d. Super computers are used in scientific research.
e. Analog computers represent the data in discrete variable.

4. Match the following: combine features of laptops and
a. Laptop handheld computers
middle size computer
b. Analog computer works on continuous flow of data
c Workstation small portable computer
d. Minicomputer built in network support
e. Tablet

5. Fill in the blanks:
a. Temperature, voltage, etc can be measured by............................
computer.
b. ............................ computers generally connected in network.
c. ............................ can support up to thousand users simultaneously.
d. ............................ used in research and whether forecast.

GREEN Computer Book-8 25

e. Hybrid computers use both .......................and .....................

6. Choose the best answer:
a. A ..............computer is used in scientific research.
i. Hybrid computer
ii. Analog computer
iii. Super computer
b. Computer used in server is called ..............
i. analog computer
ii. super computer
iii. minicomputer
c. A computer that is mostly used in a hospital..............
i. analog computer
ii. hybrid computer
iii. digital computer
d. A digital computer displays the output as..............
i. discrete data
ii. continuous data
iii. none
e. An analog computer displays the output as..............
i. discrete data
ii. continuous data
iii. none

7. Tech terms.
a. The most powerful and expensive compuer used in weather forcastinf
and aircraft launching.
b. A large and expensive computer capable of supporting hundreds or
even thoussands of users simultaneously.
c. The medium size computer capable of of supporting upto 200 users
simultaneously.
d. The light weight, portable computer with built in monitor, keyboard,
hard disk, drive battery and AC adapter.
e. The single user computer typically linked together to form a local
area network.
f. The computer which operates on discrete data.

26 GREEN Computer Book-8

4 Computer Software

Introduction

Software is a set of programs, which is designed to perform a well-defined
functions. A program is a sequence of instructions written to solve a particular
problem. Software is the soul of a computer. Without software, a computer
cannot do anything. Software instructs hardware parts to perform a certain
task. Basically, there are two types of software:

• System Software • Application Software

Software

System Application
Software Software

Operating Packaged Tailored
Software Software Software

Language Know More
Processor
Software is an intangible product
Device and moreover it is a process.
Driver

Utility
Software

System Software

The system software is a collection of programs designed to operate, control,
and extend the processing capabilities of a computer itself. Computer
manufacturer prepare various kinds of system software. These software
products 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.

GREEN Computer Book-8 27

Features of system software are as follows:
• Close to system hardware.
• Fast in loading and processing.
• Difficult to design and develop.
• Difficult to understand.
• Less interactive.
• Generally written in low-level language.

Types of system software: 2. Language processor
1. Operating system software 4. Utility software
3. Device driver

Operating system:

The software which controls and coordinates overall functions of a computer is
called operating system software. An operating system is a program that acts
as an interface between the software and the computer hardware. It manages
overall resources and operations of a computer. It helps to run application
program. Some of the popular operating systems are: Windows-7, Windows10,
Unix, Linux, Mac - OS, etc.

Functions of Operating System

• Memory Management : Keeps track of primary memory i.e. what part of
it is in use by whom, what part is not in use, etc. and allocates the memory
when a process or program requests it.

• Processor Management : Allocates the processor CPU to a process and de-
allocates processor when it is no longer required.

• Device Management : Keeps track of all devices. This is also called I/O
controller that decides which process gets the device, when, and for how
much time.

• File Management : Allocates and de-allocates the resources and decides
who gets the resources.

• Security : Prevents unauthorized access to programs and data by means of
passwords.

• Control over system performance : Records delays between request for a
service and from the system.

• Helps to execute commands and run application program.

28 GREEN Computer Book-8

Language processor

A language processor is a special type of a computer software that has the
capacity to translate the source codes (program codes) into machine codes. It is
also called a language translator. There are three types of language processors:

a. Interpreter: Interpreter translates program written in a high level language
into a machine language. It translates the program code one after another.

Source code Interpreter Object code

b. Compiler: Compiler translates program written in a high level language
into a machine language. It translates the whole program at once.

Source code Compiler Object code

c. Assembler: Assembler translates the program written in assembly
language into a machine language. An assembler enables software and
application develops to access, operate and manage a computer's hardware,
architecture and components.

Source code Assembler Object code

Interpreter and compiler both translate high level language to machine
language. But there are some differences between an interpreter and a compiler
which are given below:

Interpreter Compiler

1. Translates program one statement 1. Scans the entire program and

at a time. translates it as a whole into

machine code.

2. It takes less amount of time to 2. It takes large amount of time

analyze the source code but the to analyze the source code but

overall execution time is slower. the overall execution time is

comparatively faster.

3. No intermediate object code 3. Generates intermediate object

is generated, hence is memory code which further requires

efficient. linking, hence requires more

memory.

4. Easy for debugging. 4. Comparativelyhardfordebugging.

5. Programming language like 5. Programming language like C,

Python, Ruby uses interpreters. C++ uses compilers.

GREEN Computer Book-8 29

Device Driver

A device driver is a small piece of software that tells the operating system
and other software how to communicate with a piece of hardware. Types of
device drivers: printer drivers, display drivers, ROM drivers, BIOS drivers,
USB drivers, VGA drivers, sound card drivers, mother board drivers, virtual
device drivers.

There are many more drivers included in a system. When a user is installing
an operating system, it may automatically install the required drivers.

Utility software

Utility software is a part of system software that enhances the operations of
computer or specific program. It manages memory, scans and stops viruses,
compresses files, increases the speed of computer processing, scans disk to
find bad sector of hard disk etc.

Application Software

Application softwares are designed

to satisfy a particular need of a user.

They are is directly designed for

users. User can solve their various

problems. Examples of application

softwares are following: Payroll

Software, Inventory Management

Software, Microsoft Office,
Microsoft Excel, etc.

Features of application software are as follows:
• Close to user.
• Easy to design and develop.
• More interactive.
• Slow in operation.
• Generally written in high-level language.
• Easy to understand.
• Bigger in size and requires large storage space.

30 GREEN Computer Book-8

There are two types of application softwares:

Customized (Tailored Software)

It is the software designed to address the user's need. It is developed on the
demand of users to perform the user-specific task. It is very expensive. It is
written in high level language. Some of the examples of customized software
are library management system, payroll system, etc. Some of the leading
software companies that who develop customized software are: Javra Software
Nepal, Midas Technologies Pvt.Ltd, F1Soft Pvt Ltd, etc.

Packaged Software

It is user friendly software consisting of one or more programs created to perform
a particular type of work. It is developed to fulfill common requirement of
users. It can perform tasks like preparing document and presentation, keeping
accounting records, maintaining database, playing audio and video, editing
graphics, etc.

Some examples of packaged software are:
Word processing software: Word Pad, Note Pad, Ms-Word, etc.
Database Management System Software: Microsoft Access, Oracle, SQL –
Server, etc
Spreadsheet software: Lotus1-2-3, Microsoft Excel, etc.
Multimedia software: Window Media Player, Audio/ Video Converter, etc.
Presentation software: Microsoft Power Point
Graphics software: Adobe Photoshop, Flash, CorelDraw, etc.
Web development software: PHP, Drupal, HTML, etc.

GREEN Computer Book-8 31

POINTS TO REMEMBER
1. Computer software is a set of programs that instruct a computer to

perform certain task.
2. A device driver is a small piece of software that tells the operating system

and other software how to communicate with a piece of hardware.
3. System software is a collection of programs designed to operate, control

and manage the actual operation of the computer equipment.
4. Operating system software allows a computer to manage resources and

control the overall functions of a computer.
5. Application softwares are those softwares which are designed for

specific function directly for the user.
6. Software is a product.
7. There are two types of application software: Customized software and

Packaged software.
8. Utility software is a part of system software that enhances the operations

of computer or specific program.
9. A language processor is a special type of a computer software that has

the capacity to translate the source code or program codes into machine
codes.

Exercise

1. Answer the following questions:

a. Define software. Write its type.

b. Explain system software. List out the features of system software.

c. Write the functions of operating software.

d. What is application software? What are the features of a computer?

e. Why is customized software developed?

f. Write a difference between packaged software and tailored software.

g. What is language processor? List its types.

h. Define the following:

i. Device driver ii. Utility software iii. Compiler iv. Interpreter

j. Write differences between applications, software and system software.

32 GREEN Computer Book-8

2. Fill in the blanks:
a. ............................ software is very close to the system.
b. ............................ software organizes and manages memory.
c. ............................ software is close to the user.
d. Unix is an example of .............................
e. ............................ is written in high level language.
f. ............................ translate high level language into machine
language.
g. ............................ software is designed to address the user's need.

4. Match the following: Set of programs
a. Tailored software Library management system
b. Utility software Scan viruses
c. Operating system Microsoft Office
d. Software used to coordinate the hardware of
e. Packaged software the computer

5. State whether these statements are 'True' or 'False':
a. Packaged software manages files and folders.

b. Linux is an application software.

c. A computer is a useless machine without software.

d. Windows 7 is an operating system.

e. Packaged software is used to coordinate the hardware of a computer.
f. Source code is written in low level language.

6. Write technical terms for the following statements:
a. A set of instructions given to a computer to perform a task.

b. A set of programs that tells computer hardware what to do and how
to do.

c. A software designed to perform general tasks.

d. A software designed to perform specific tasks.

e. A language processor that converts the whole program written in
high level language into machine language.

f. A language translator which translates the high level language one
statement at a time into machine language.
GREEN Computer Book-8 33

5 Types of Operating

System

Introduction

The software which controls and coordinates
overall functions of a computer is called
operating system software. An operating system
is a program that acts as an interface between
the software and the computer hardware. An
operating system is a software which performs
all the basic tasks like file management, memory
management, process management, handling input and output, and controlling
peripheral devices such as disk drives and printers. It helps to run application
programs. Some of the popular operating systems are: Windows 7, Windows
8, windows 10, Unix, Linux, VMS, OS/400, AIX, etc.

Use of operating systems started with the development of modern computers
(from the very first generation of computer) and they keep evolving with
time. In this chapter, we will discuss some of the important types of operating
systems which are most commonly used.

Mainly there are two types of operating systems:

1. On the basis of Mode of User 2. On the basis of Interface

1. On the basis of Mode of User

Following operating systems are categorized on the basis of mode of user.

Batch Operating System

The users of a batch operating system do not interact with a computer directly.
Each user prepares his job on an off-line device like punch cards and submits it
to the computer operator. To speed up processing, jobs with similar needs are
batched together and run as a group. The programmers leave their programs
with the operator and the operator then sorts the programs with similar
requirements into batches.

34 GREEN Computer Book-8

Disadvantages of batch operating system:

• Repeated jobs are done

fast in batch systems User

without user interaction. Job Batch
• You don’t need special
User Job Jobs
hardware and system Operator
support to input data in Computer

batch systems. User Job Jobs
• Best for large Job Batch

organizations but small

organizations can also User
benefit from it.

• Batch systems can work

offline so it makes less stress on processor.

• In batch systems the processor knows how long the job is as it is queued.

• Sharing of batch system for multiple users.

• The idle time batch system is very less.

• You can assign specific time for the batch jobs so when the computer is idle

it starts processing the batch jobs.

The problems with Batch Systems are as follows:
• Lack of interaction between the user and the job.
• CPU is often idle, because the speed of the mechanical I/O devices is slower

than the CPU.
• It is costly and difficult to debug the batch system.
• Difficult to provide the desired priority.
• Computer operator must be trained for using batch system.

Time-sharing Operating Systems

Time-sharing is a technique which enables many people, located at various
terminals, to use a particular computer system at the same time. Time-sharing
or multitasking is a logical extension of multiprogramming. Processor's time
which is shared among multiple users simultaneously is termed as time-
sharing.

The main difference between Multi-programmed Batch Systems and Time-
Sharing Systems is that Multi-programmed Batch Systems maximize the use of
processor but Time-Sharing Systems minimize the response time.

GREEN Computer Book-8 35

Advantages of Time sharing operating systems are as follows:
• Provide the advantage of quick response.
• Avoid duplication of software.
• Reduce CPU idle time.

Disadvantages of Time-sharing operating systems are as follows:
• Problem of reliability.
• Question of security and integrity of user programs and data.
• Problem of data communication.

Distributed Operating System

Distributed systems use multiple central processors to serve multiple real-time
applications and multiple users. Data processing jobs are distributed among
the processors accordingly.

The processors communicate with one another through various communication
lines (such as high-speed buses or telephone lines). These are referred as
loosely coupled systems or distributed systems. Processors in a distributed
system may vary in size and function.

These processors are referred as sites, nodes, computers, and so on.

The advantages of distributed systems are as follows:
• With resource sharing facility, a user at one site may be able to use the

resources available at another.
• Speedup the exchange of data with one another via electronic mail.
• If one site fails in a distributed system, the remaining sites can potentially

continue operating.
• Better service to the customers.
• Reduction of the load on the host computer.
• Reduction of delays in data processing.

Disadvantages of distributed operating systems:-
• Security problem due to sharing
• Some messages can be lost in the network system
• Bandwidth is another problem if there is large data then all network wires

to be replaced which tends to become expensive.
• Overloading is another problem in distributed operating systems.
• If there is a database connected on local system and many users accessing that

database through remote or distributed way then performance becomes slow.
36 GREEN Computer Book-8

• The databases in network operating is difficult to administrate then single
user system

Network Operating System

A Network Operating System runs on a server and provides capability to
the server to manage data, users, groups, security, applications, and other
networking functions. The primary purpose of a network operating system is
to allow shared file and printer access among multiple computers in a network,
typically a local area network (LAN), a private network or to other networks.

Examples of network operating systems include Microsoft Windows Server
2003, Microsoft Windows Server 2012, UNIX, Linux, Mac OS X, and BSD.

The advantages of network operating systems are as follows:
• Centralized servers are highly stable.
• Security is managed by server.
• Upgrades to new technologies and hardware can be easily integrated into

the system.
• Remote access to servers is possible from different locations and types of

systems.

The disadvantages of network operating systems are as follows:

• High cost of buying and running a server.

• Dependency on a central location for most operations.

• Regular maintenance and updates are required.

Real-Time Operating System

A real-time system is defined as a data processing system in which the time
interval required to process and respond to inputs is so small that it controls
the environment. The time taken by the system to respond to an input and
display of required updated information is termed as the response time. So in
this method, the response time is very less as compared to online processing.

Real-time systems are used when there are rigid time requirements on the
operation of a processor or the flow of data and real-time systems can be used
as a control device in a dedicated application. A real-time operating system
must have well-defined, fixed time constraints, otherwise the system will
fail. For example, scientific experiments, medical imaging systems, industrial
control systems, weapon systems, robots, air traffic control systems, etc.

GREEN Computer Book-8 37

Advantages of Real-Time Operating System

• It takes very less time to respond the input and display of required updated
information.

• It works when there are rigid time required on the operation.
• It guarantee that eritical task complete on time.
• Task scheduling and shifting.
• Task can have priority.
• Inter task communication.

• Portable.

There are two types of real-time operating systems.

Hard real-time systems

Hard real-time systems guarantee that critical tasks complete on time. In hard
real-time systems, secondary storage is limited or missing and the data is
stored in ROM. In these systems, virtual memory is almost never found.

Soft real-time systems

Soft real-time systems are less restrictive. A critical real-time task gets priority
over other tasks and retains the priority until it completes. Soft real-time
systems have more limited utility than hard real-time systems. For example,
multimedia, virtual reality, Advanced Scientific Projects like undersea
exploration and planetary rovers, etc.

2. On the basis of Interface

There are two types of operating systems on the basis of interface.

a. Character User Interface (CUI)

A CUI is a text-based interface where instructions are given to the computer
by typing commands. In CUI, a user interacts with application software
through the commands. It is also known as Command Line Interface (CLI).
Novell Netware Server, MS-DOS, etc. are the CLI operating system.

b. Graphical User Interface

A Graphical User Interface (GUI) based operating system allows a user
to interact with the computer system by pointing and selecting graphical
symbols. Some of the GUI operating systems are: Windows 2007, Windows
2008, Vista, Windows XP, Mac-OS, etc.

38 GREEN Computer Book-8

POINTS TO REMEMBER
1. An operating system is a program that acts as an interface between the

software and the computer hardware.
2. The use of operating systems started with the development of modern

computer.
3. The users of a batch operating system do not interact with the computer

directly.
4. Time-sharing is a technique which enables many people, located at

various terminals, to use a particular computer system at the same time.
5. Distributed systems use multiple central processors to serve multiple

real-time applications and multiple users.
6. A Network Operating System runs on a server and provides the server

the capability to manage data, users, groups, security, applications, and
other networking functions.
7. A real-time system is defined as a data processing system in which the
time interval required to process and respond to inputs is so small that
it controls the environment.

Exercise

1. Answer the following questions:
a. Define an operating system. Give some examples.
b. List the types of operating systems on the basis of mode of users.
c. What is batch operating system? What are the problems with batch
operating system?
d. What is time sharing operating system? Write advantages and
disadvantages.
e. Define the network operating system with examples.
f. What are the advantages and disadvantages of network operating system?
g. What is real time operating system? Write its types
h. How many operating systems are there on the basis of interface?

GREEN Computer Book-8 39

2. Fill in the blanks:
a. ........................... is a text-based interface where instructions are given
to the computer by typing commands.

b. ........................... based operating system allows a user to interact with
the computer system by pointing and selecting graphical symbols.

c. ........................... systems guarantee that critical tasks complete on
time.

d. ........................... have more limited utility than hard real-time systems.

e. ........................... system is a software which performs all the basic tasks
like file management, memory management, process management,
handling input and output, and controlling peripheral devices such
as disk drives and printers.

3. Write the full form of the following: LAN CPU CUI
GUI CLI OS I/O

4. a. GU based operating system allows a user to interact with computer
by typing commands.

b. Soft real time operating system is less restrictive.

c. Distributed opening system use, multiple central processor to serve
multiple real-time application and user.

d. Time sharing is physical extension of multi programming.

e. The user of batch operating system interact with a computer directly.

5. Match the following. i. complete critical tasks
ii. network O/S
a. CLI iii. donot interact with computer directly
b. GUI iv. Graphical user interface
c. UNIX v. Command line interface
d. Batch O/S
e. Hard real time system

40 GREEN Computer Book-8

6 Number System

Introduction

A number system is a way of representing numbers. A set of values used to
represent different quantities is known as a Number System. When we type
some letters or words, the computer translates them in to numbers as the
computer can understand only numbers. The number system can mainly be
categorized into two types.
1. Non-Positional Number System: The number system in which different

symbols are used in different positions and places is called non-positional
number system. It does not make any positional significance on the value
of the number system is called non-positional number system. The roman
number system such as I, V, X, XII etc are used to represent non-positional
number system.
2. Positional Number System: A computer can understand the positional
number system. The positional number system uses different symbols at
different positions or places that make the positional significance on the
value of the number.

There are different types of number systems:
• Decimal Number System
• Binary Number System
• Octal Number System
• Hexadecimal Number System

Decimal Number System

The number system that we use in our day-to-day life is the decimal number
system. The decimal number system has base 10 as it uses 10 digits from 0
to 9. In the decimal number system, the successive positions to the left of

GREEN Computer Book-8 41

the decimal point represent units, tens, Octal Binary
hundreds, thousands and so on. Each position Number number
represents a specific power of the base 10. For
example, the decimal number 3562 consists 0 0
of the digit 2 in the units position, 6 in the 1 1
tens position, 5 in the hundreds position, and 2 10
3 in the thousands position, and its value can 3 11
be written as 4 100
5 101
(3 x 1000) + (5 x 100) + (6 x 10) + (2 x l) 6 110
7 111
(3 x 103) + (5 x 102) + (6 x 101) + (2 x 100) 8 1000
9 1001
3000 + 500 + 60 + 2

3562

Binary Number System

A digital computer represents all kinds of data and information in the binary
system. The Binary Number System consists of two digits 0 and 1. Its base is 2.
0 represents False or Off state and 1 represents True or On state. A combination
of binary numbers may be used to represent different quantities like 1001. The
positional value of each digit in binary number is twice the place value or face
value of the digit of its right side. The weight of each position is a power of 2.

The place value of the digits according to position and weight is as follows:

Position 3210
Weight 23 22 21 20

Example:
101012 = 1 × 24 + 0 × 23 + 1 × 22 + 0 × 21 + 1 × 20
= 16 + 4 + 1
= (21)10

Octal Number System

The Octal Number System consists of eight digits from 0 to 7 (0, 1, 2, 3, 4, 5, 6,
7). The base of octal system is 8. Each digit position in this system represents a
power of 8. Any digit in this system is always less than 8. Octal number system
is used as a shorthand representation of long binary numbers. The place value

42 GREEN Computer Book-8

of each digit according to position and weight is as follows.

Position 43210
Weight 84 83 82 81 80

Example: 278 = 2 × 81 + 7 × 80 = 16 + 7 = 2310 Binary
number
Octal
Number 000
001
0 010
1 011
2 100
3 101
4 110
5 111
6
7

Hexadecimal Number System

The Hexadecimal Number System consists of 16 digits from 0 to 9 and A to

F. The alphabet letters A to F represent decimal Hexadecimal Binary
numbers from 10 to 15. The base of this number Number number

system is 16. Each digit position in hexadecimal 0 0000

system represents a power of 16. This number 1 0001
system provides shortcut method to represent 2 0010
long binary numbers. 3 0011
4 0100
The place value of each digit according to position 5 0101
and weight is as follows:

Position 4 3 2 1 0 6 0110

Weight 164 163 162 161 160 7 0111

Example: 2F16 8 1000
= 2 × 161 + 15 × 160 9 1001
A 1010
= 47 B 1011

Number Conversion C 1100

There are many methods for number conversion D 1101
from one base to another base. We discuss about E 1110
the following number conversion: F 1111

GREEN Computer Book-8 43

• Binary to Decimal
• Binary to Octal
• Binary to Hexadecimal
• Decimal to Binary
• Octal to Binary
• Hexadecimal to Binary
• Decimal to Octal
• Octal to Decimal

Binary to Decimal

(1101)2 = ( ? )10

Position 3210

Weight 23 22 21 20

Face value 1 1 0 1

Step 1 : 1 x 23 + 1 x 22 + 0 x 21 + 1 x 20

Step2 : 1 x 8 + 1 x 4 + 0 x 2 + 1 x 1 =8 + 4 + 0 + 1 = (13)10

Binary to Octal
Steps:

• Make a group of three digits from right to left.

• See in the table of octal equivalent binary.

• Add zero to the left most side if there are less number of digits than
three.

(1101111)2 = ( ? )8

001 (added two zero) 101 111
1 57

= (157)8

Binary to Hexadecimal
Steps:

• Make a group of four digits from right to left.
• See in the hexadecimal equivalent binary table.

44 GREEN Computer Book-8

• Add zero to the left most side if there are less number of digits than
four.

(111100101)2 = ( ? )16

0001 (added three zero) 1110 0101
1 E5

= (1E5)16

Decimal to Binary
Steps:

• Divide the number by 2 each time.

• Write the remainder (0 or 1).

• Arrange remainder bottom to top.
(52)10= ( ? )2

Operation Result Remainder

52/2 26 0

26/2 13 0

13/2 6 1

6/2 3 0

3/2 1 1

1/2 0 1

(110100)2

Octal to Binary
Steps:

• Plot the octal number in table.
• See the octal equivalent binary table.
• Write the equivalent binary number.
(7602)8 = ( ? )2

7602
111 110 000 010
(111110000010)2

GREEN Computer Book-8 45

Hexadecimal to Binary
Steps:

• Plot the hexadecimal number in table.

• See the hexadecimal equivalent binary table.

• Write the equivalent binary number.
(AC107)16 = ( ? )2

A C 1 0 7
1010 1100 0001 0000 0111

(10101100000100000111)2

Decimal to Octal
Steps:

• Divide the number by 8 each time.

• Write the remainder.

• Arrange remainder bottom to top.
(435)10 = ( ? )8

Operation Result Remainder

435/8 54 3

54/8 6 6

6/8 0 6

(663)8

Octal to Decimal

(324)8 = ( ? )10

Position 21 0
80
Weight 82 81 4

Face value 3 2

Step 1: 3 x 82 + 2 x 81 + 4 x 80
Step 2: 3 x 64 + 2 x 8 + 4 x 1
Step 3: 192 + 16 + 4 = (212)10

46 GREEN Computer Book-8

Binary Calculation

Binary number calculation includes:

• Binary Addition,
• Binary Subtraction,
• Binary Multiplication and
• Binary Division.
We discuss only addition, subtraction and multiplication.

Binary Addition Example: 1 Example: 2
Rules for binary addition 100010 111101
0+0=0
1+0=1 +110111 +101011
0+1=1 1011001 1101000
1 + 1 = 10

Binary Subtraction Example: 1 Example: 2
Rules for binary subtraction 11000010 101010
0–0=0 -11011
1–0=1 -111111 1111
1–1=0 10000011
0 – 1 = 1 ( by borrowing from left)

Binary Multiplication Example: 1 Example: 2
Rules for binary multiplication 11111 11101
0x0=0 x 111 x 101
0x1=0 11111 11101
1x0=0 11111. 00000.
1x1=1
11111 . 11101 .
11011001 10010001

GREEN Computer Book-8 47

Binary Multiplication Example: 1 Example: 1
Rules for binary division, 101 101010 1000 100100
0÷0=0 101 101 11011010
0÷1=0 × 010
1 ÷ 0 = not defined 111
1÷1=1
× 110

– 110

×10

POINTS TO REMEMBER

1. A numbering system is a way of representing numbers.
2. In a number system, different symbols are used in different positions

and places.
3. A computer can understand the positional number system.
4. The decimal number system has base 10 as it uses 10 digits from 0 to 9.
5. The Binary Number System consists of two digits 0 and 1.
6. The Octal Number System consists of eight digits from 0 to 7.
7. The Hexadecimal Number System consists of 16 digits from 0 to 9 and

A to F.

Exercise

1. Answer the following questions:

a. List out four types of number systems.
b. Give the importance of number systems.
c. Differentiate between binary and decimal number system.
d. Define the term radix in number base system.
e. What is the hexadecimal number system?
f. Explain octal number system in brief.

2. Convert the following binary number to decimal number system.

a. 101002 = ( ? )10 b. 101112 = ( ? )10
c. 1001112 = ( ? )10 d. 1111012 = ( ? )10

48 GREEN Computer Book-8

3. Convert the following decimal number to binary number system.

a. (908)10 = ( ? )2 b. (75)10 = ( ? )2

c. (93)10 = ( ? )2 d. (101)10 = ( ? )2

4. Convert the following binary number to octal number system.

a. (1011010)2 = ( ? )8 b. (1010111)2 = ( ? )8

c. (10101111010)2 = ( ? )8 d. (10111111)2 = ( ? )8

5. Convert the following binary number to hexadecimal number system.

a. (1011010)2 = ( ? )16 b. (1010111)2 = ( ? )16

c. (10101111010)2 = ( ? )16 d. (10111111)2 = ( ? )16

6. Convert the following hexadecimal number to binary number system.

a. (C09)16 = ( ? )2 b. (CAB)16 = ( ? )2

c. (1000EF)16 = ( ? )2 d. (1011)16 = ( ? )2

7. Convert the following decimal number to octal number system.

a. (291)10 = ( ? )8 b. (203)10 = ( ? )8

c. (1909)10 = ( ? )8 d. (721)10 = ( ? )8

8. Convert the following octal number system to decimal number system.

a. (100)8 = ( ? )10 b. (100)8 = ( ? )10

c. (1037)8 = ( ? )10 d. (172)8 = ( ? )10

9. Perform the binary calculation of the following.

a. 1101110 + 101010 b. 10110 + 10111 - 1001

c. 100110 - 1101 d. 110001 x 11

e. 10111 x 101 f. 1110101 x 111 + 1111

g. 110101 + 111001 × 111 h. 1111111 × 10 – 111101

10. Perform following binary division.

a. (1111001)/(111) b. (10101011)/(1010)

c. (111110001)/(101) d. (11110101101)/(111)

e. (10101010101)2/(101)2 f. (10000001)2/(100)

GREEN Computer Book-8 49

7 Advanced Features of

Microsoft Word

Introduction

Word processing is one of the most popular and widely used application
softwares. Word processing relates to the work with the text. This software
provides users to create, edit and format documents in systematic and scientific
ways. Microsoft Word (MS Word) is one of the most popular word processing
softwares.
Before the use of computers or any other electronic devices, people used to
write on paper to send letters and other informative matters on their own.
Afterwards, they started using typewriters to do similar jobs.
Later on, electronic typewriters and computers came into use. Then people
started using such devices to prepare these informative matters. MS Word is
a word processing program that allows for the creation of both simple and
sophisticated documents. It has templates and wizards to help you create
useful documents such as resumes, letters and fax cover sheets. There are also
features that allow you to add professional looking graphics to your documents.
MS-Word is available in different versions such as MS-WORD 6.0, MS-
WORD97, MS-WORD 2000 , MS-Word 2003, MS-Word 2007 and MS-Word
2010. They are MS-Word 2007 and MS-Word 2010 , which we will deal with in
this lesson. It comes as a part of office package. All word processing softwares
are word processors. You have studied most of the features of Ms-word
previous classes.
Now, you will study some advance features.

Typing Text in Word
Typing text on the left side of the screen.
1. Position your cursor where you would like to start typing.
2. Start typing.

50 GREEN Computer Book-8