Let's Log In Computer Science Book 6 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

6

Authors:

Sushil Upreti Sunil Kumar Gharti

vedanta

Vedanta Publication (P) Ltd.
j]bfGt klAns];g kf| = ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
[email protected]
www.vedantapublication.com.np

vedanta Book

Let's Log in 6

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: Sunil Kumar Gharti
Sushil Upreti

© 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 kf| = ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
[email protected]
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 Introduction to Computer
2 Introduction to Computer Hardware 5
3 Introduction to Computer Software 14
4 Input and Output Devices 23
5 Storage Devices 29
6 Introduction to Operating System (MS-Windows) 40
7 Typing Tutors 49
8 Introduction to Word Processor 64
9 Introduction to Spreadsheet 74
10 Introduction to Presentation Software 95
11 ICT, Cyber Ethics and Computer Virus 113
12 Introduction to Internet and Browsing 125
13 Computer Graphics 135
14 Introduction to Multimedia 145
155

Vedanta LET’S LOG in Computer Science _ Book 6

Lesson

1 Introduction to Computers

Today computers are used all over the world. We can find computers in
houses, school, office factories, companies, and many other places. In fact,
you can find them in some pretty unlikely places, including your family car,
your home appliances, and even your alarm clock. In the past two decade,
computers have reshaped our lives at home, work, and school. The vast
majority of business now use computerized equipment in some way. Besides
producing information, the computer can be used for performing different
tasks like creating documents, presentations, databases, spreadsheets,
composing music, monitoring the condition of patients, sending messages,
etc. We can say that the twenty-first century is the age of computers.

Personal Computer System

The word "computer" is derived from the Latin word “Computare” which
means “calculation”. Computer is an electronic equipment designed to
automatically accept, store, input data, manipulate them, and produce
output results under the directions of detailed step-by-step stored program
of instructions. A set of instructions that performs particular task is called a

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program. Computer cannot do anything without a program. The instruction
in the program direct the computer to perform input operations, process the
data, and output the result. Computer follows the I-P-O (Input-Processing-
Output) cycle.

Computerized Car Computerized home appliance Computerized alarm clock

Characteristics of Computer

The characteristics of a typical modern-day computer are as follows:

1. Speed

Computer can perform complex mathematical and statistical
calculations at a very high speed.

2. Accurate and reliable

Computer is a machine that gives accurate results. But, if we input
wrong data, the processed result will be wrong, too. This is known as Garbage
In-Garbage-Out (GIGO). The output is dependent on the input given to it. It
produces correct results when we input the correct data. We can rely on the
results produced by computer.

3. Versatile

Versatility is the ability to perform different types of jobs. Computer
can perform different types of tasks efficiently. It can work with different
types of data like pictures, audio, and video.

4. Diligence

Computer can perform tasks continuously with the same speed,
accuracy, and efficiency without getting tired or bored. So, computer is
diligent. Hence, computer is an ideal machines with the capacity of doing
repetitive and huge amount of work. If therefore millions of calculations

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do do, computer performs every calculation with the same accuracy. So,
computer is diligent.

5. Storage capacity

Computer can store large amount of data and
information which can be retrieved whenever required.
This large storage capacity is achieved through auxiliary
storage in computer. Storage capacity of computer is
measured in terms bytes, kilobytes, Megabytes,
Gigabytes, or Terabytes, etc. Following table shows
the different units of storage capacity.

1 bit 1 or 0
4 bits 1 Nibble
8 bits 1 Byte, 1 Character
1024 Byte 1 Kilobyte (KB)
1024 KB 1 Megabyte (MB)
1024 MB 1 Gigabyte (GB)
1024 GB 1 Terabyte (TB)

6. Automation

Once a task is initiated, computer can proceed on its own till the
completion. Computer can be programmed to perform a series of complex
tasks involving multiple programs.

7. No Feeling

Computer is devoid of emotion. It has no feelings and no instincts
because it is machine. It makes judgements based on the instructions given
to it in the form of programs that are written by us (human beings).

Areas of Application of Computers

We know that computers are common to each and every field. You have
studied various application areas of computer. There are so many
applications of computer that it is impractical to mention all of them. Some
of the important areas of application of computer are:

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1. Banking

Computer technology has brought huge change
in banking. Computer is used for various tasks, such
as online enquiry of customer’s balance, cheque
verification, updating the balance, calculating
interests, and printing statements for customers.
These days, banks also provide ATM service to
the customers. A customer with an ATM card can
perform a cash transaction immediately at the ATM
machine by inserting card in it.

2. Business Business

Every company requires a lot of information to
carry out its day-to-day activities. Computers is used
in business for preparing salary sheet, sales record,
stock control, and maintenance of staff records. They
are also used for sales forecasting and production
planning.

3. Science and Technology Science and Technology

Computers are now increasingly
employed to improve scientific and
technological advancements. They are being
used to scan space for signs of different forms
of life. They are also used in the design and
operation of human-made satellites, space
exploration vehicles, rockets, and robotics.
Weather forecasting has become much easier
and reliable with the advent of computer.

4. Education Education

Computer has made direct impacts on
education in the form of systems that are
actually involved with teaching process.
More and more schools are adding computer
technology to their curricula to teach both
computer skills and other subjects.

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They can place instructions differently for each student, animate important
concepts, and use interactivity to involve students in the learning process.
Basic and secondary schools are using computers to play multimedia
educational programs and to teach kids to explore the web information.

5. Health and Medical field Health and Medical field

Computer is widely used in hospitals to help
doctors in diagnosis, and getting information on
patients, diseases, treatment, drugs, etc. They are
also used in administration and in keeping patient
records.

6. Home Home

At home, computer can be used in learning,
playing games, listening to music, or watching movies.
The computer can also be used in storing personal
information, such as date of birth, addresses, telephone
numbers, photo albums, etc. at home. Today, people
use home computer to access the internet.

7. Library Library

Maintaining records of books and borrowers is
well suited to a computer system. Using a computer
enables library personnel to answer queries about the
status of books more easily than a manual system. A
computerized system also enables to find out if the
book can be issued. If the maximum limit of the books
is already reached, the user does not get another book.

8. Communication Sector

Computer has played an important role
in the field of communication. E-mail and
Chat are facilities supported by computers to
send and receive messages. Internet telephony
(net call) is also important service of computer
through which people can easily talk from one Communication Sector

place to another. Computer communication is one of the cheapest, most
reliable, and fastest communication media.

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9. Computers in Simulation

Computer simulation involves typing to predict what will happen in a
real-life situation from a model of that situation. For example, an engineer,
when designing a bridge, would like to know the effects of various loading
conditions on the bridge, without actually having to build the bridge just
yet. An aircraft designer would like to know the effect on lift of changing the
shape of the wings or the tail, without having to build aircraft with these
changes. Computer is a useful tool in providing answers to these questions.
Computer Aided Design (CAD) is widely used in the design of electronic
circuits, ships, roads, and cars. Programs are also available which simulate
the timing of traffic lights, the effect of hunting on wild-life populations, and
even a nuclear attack for testing national defences.

10. Computers in Military

Computers are extensively used in defence. Nowadays, smart
weapons are being widely used in military operations. Smart weapons use
microprocessor-based control systems. Modern tanks, torpedoes, missiles,
etc. employ computerized control systems. A guided
missile uses internal computer for its control.
Computer’s memory holds the detailed map of the
target area. Photographs of the target are taken and
compared with stored map before the missile hits the
target.

Computer plays very important role in military Computers in Military

communications. Radar systems employ computers
for processing data and displaying images. Computerized control system
provides much more information about range, height, etc. of the target.
Fighter planes are equipped with computers for their quick activity.

POINTS TO REMEMBER

Computer is an electronic device that processes data, converting it into
information that is useful to people.
Data is a collection of facts that is entered as input in the computer
Processing is the action performed on the data by the computer.

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Information is the output received after the data is processed.

Storage devices like hard disks, floppy disks, CD-ROM, magnetic tape, etc. are
used to hold data and programs permanently for future use.

Computer technology is playing an ever-growing role in schools, where
students are being taught computer skills at young ages.

Computers are involved in nearly every aspect of the health care.

The home computer is used in learning, playing games, listening to music, or
watching movies.

Computers are used in various fields like banking system, desktop publishing
system, simulation, music and entertainment, military, etc.

xercise

1. Answer the following questions:

a) Define computer.
b) List and explain some important characteristics of computer.
c) Why is computer called a diligent machine?
d) What is garbage-in-garbage-out?
e) Why is computer called a versatile machine?
f) What are secondary storage devices? Give two examples.
g) Name three application areas of computer.
h) What is the most popular use for home computers?

2. Fill in the blanks:

a) Computer is an ................................ machine.
b) Computer accepts the data from user through ................................ devices.
c) Computer cannot do anything without a ................................ .
d) Computer can store large amount of ........................... and .............................
e) ........................ have no feelings and no instincts because they are machines.

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f) A customer with an .............................. card can perform a .............................
transaction immediately.

g) ................................ is widely used in the design of electronic circuits, ships,
roads and cars.

3. Match the following: Group B

Group A

a) Speed i) Huge amount of data can be stored

b) Versatile ii) Takes only few seconds for calculations

c) Diligence iii) Does not have emotion, taste and experience.

d) Storage iv) Use of computer is not limited to any single task

e) Accuracy v) Computers give correct answer

f) No Feeling vi) Never gets tired or bored of doing tasks

4. State whether the following statements are True or False:

a) Computer can do any work without instruction.
b) Computer is capable of performing multiple tasks at a very

high speed.

c) The set of instructions given to computer is known as program.

d) Computer takes long time for calculations.

e) Byte is the smallest unit of memory.
f) Computers assist teachers in teaching their students easily

and quickly.

g) Computer can take its own decision as you can.
h) Computer has played an important role in the field of

communication.

i) Computer cannot be used in video editing.

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

1

2

3
4

5

ACROSS Give correct answer
2 Can store large amount of data
4 Never get tired or bored of doing tasks
5

DOWN Ability to perform different types of jobs.
1 Take a few seconds for calculations
3

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Lesson Introduction to
Computer Hardware
2

In computer technology, there are mainly two components: hardware
and software. All the physical components of a computer are known as
hardware and all the computer programs are known as software. These two
terms emphasize the fact that the physical components and programs are
two essential parts of a functional computer system.
In order to produce useful output from the computer, the hardware and
software must work together. Thus, there is a special relationship between
hardware and software. Nothing useful can be done with the computer
hardware on its own. Similarly, the software cannot be utilized without the
help of hardware.
The physical parts of a computer are monitor, keyboard, mouse, printer,
hard disk drive, and DVD (Digital Versatile Disc) drive that you can
touch. Some pieces of computer hardware which are inside the casing are
motherboard, microprocessor, RAM, ROM, sound card, graphic
card, etc. All these work in coordination with each other.

Computer Hardware

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The complete computer system consists of four different types of hardware
components. They are:

Input Unit
Central Processing Unit
Output Unit
Secondary Storage Unit

Input Unit

A personal computer would be useless if you could not interact with it
because the machine could not receive instructions or deliver the results
of its work. Input unit receives data and instructions from the user or
from another computer system (such as computer on the Internet). The
most commonly used input device is the keyboard, which accepts letters,
numbers, and commands from the user. Another usually used input device
is the mouse, which lets us select options from on-screen menus. We use a
mouse by moving it across a flat surface and pressing its buttons. A variety
of other input devices work with the personal computer, too: Keyboard,
Mouse, Joystick, Light pen, Scanner, Trackball, bar code reader,
Microphone, webcam, etc. are the examples.

Keyboard web camera

Central Processing Unit

Central Processing Unit, commonly known as CPU, is
the most important part of the computer system. The
CPU is the brain of computer. It does all the calculations
and processing. Every task done by computer must be
interpreted and executed by the processor. This makes
the processor the most important component on the
motherboard. It also controls the operations of the
other parts and devices in a computer system.

Central Processing Unit

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The CPU consists of three parts:

Arithmetic and Logic Unit (ALU)
Control Unit (CU)
Memory Unit (MU)

CENTRAL PROCESSING UNIT

Central Processor

Input ALU CU Output

Memory Unit

ROM RAM Cache

STORAGE

Arithmetic and Logic Unit (ALU)

ALU performs all the arithmetic operations like addition (+), subtraction
(-), multiplication (*), and division (/). It also performs all the logical
comparisons. The logical comparisons include greater than (>), lesser
than (<), greater than equal to (>=), less than equal to (<=), equal to
(=) and not equal to (<>).

Control Unit

Imagine your classroom without a teacher or class monitor. If there was no
class teacher or class monitor, the students would do as they wanted and
it would make the class noisy. The class teacher or class monitor controls
and maintains discipline in the class. Similarly, the Control Unit controls
movement of information among the memory, the ALU, and other parts of
the machine.

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The control unit is the logical hub of the computer. Many instructions
carried out by the control unit involve simply moving data from one place to
another: from memory to storage, from memory to the printers and to other
devices.

Memory Unit

Just as the lessons you learn at school are captured in your brain, computer
also has a brain where it stores the information or data entered. This part
of computer is called memory. In a computer system, memory is required to
store the data and instructions entered from the input devices as well as the
result of the processing given by the CPU. The information in the memory
can be changed or erased. It can also be retrieved.

Output Unit

The output unit delivers information from computer to an external device.
The output unit displays the results of processing and other information
from computer to the user in a human-understandable language. Monitor
and Printer are the most common output unit or devices. A monitor
displays the result of a task performed by the computer. The result displayed
on the screen of the monitor is called the soft copy of the output.
A printer is used to take printouts as permanent documents on paper. This is
called the hard copy of the output. Some other output devices are Plotter,
Speaker, and Headphone, etc.

Printer

Monitor Plotter

Speakers Headphones

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Secondary Storage Unit

When you work on computer, it stores information temporarily. As soon as
it is switched off, the information is lost. So, you need a place where you can
store data on a long-term basis. This will ensure that the data can be used
as and when required.

The memory where the programs and data are stored on a long-term basis
is called secondary storage memory. It is needed in computer because
the programs and data in the primary memory are lost when the computer
is switched off. The most commonly used devices for secondary memory are:
Hard Disk, Compact Disc, Flash Drive, etc.

Hard Disk

A hard disk is the most popular secondary storage device
of a computer. It is made up of a collection of disks called
platters. It can store large amount of data and provides
relatively quick access. Hard disk is generally fitted
inside the system unit.
Hard Disk

Computers are fitted with a hard disk that has storage
capacity in terms of Gigabytes (GB) and Terabytes (TB). Nowadays,
removable hard disks are also available.

Compact Disc

Compact Disc (CD) is a small, portable, round medium
disk used for recording, playing back audio-video, storing
data and software. The different types of CD are:

CD-ROM: Compact Disc

The full form of CD-ROM is Compact Disc Read Only Memory. In a CD-
ROM, the data stored once cannot be erased but can be read a number of
times.

CD-RW

It is used to read, write, and erase data.

CD/DVD RW

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DVD

A newer technology, the DVD (Digital Versatile Disc) is a popular storage
disc. It is mostly used to store songs, movies, and softwares.

Flash Drive Flash Drive

Flash drive is a small, portable memory card that plugs
into a computer’s USB (Universal Serial Bus) port. It is a
small device we easily carry in pocket. It can be plugged
into any computer with a USB drive. Thus, it is easy to
use and it has become very popular nowadays. USB flash
drive is also called a pen drive or simply a USB drive.

POINTS TO REMEMBER

In computer technology, there are mainly two components: hardware and
software.
A complete computer system includes input, processing, output, and storage.
Hardware consists of electronic devices. The parts you can touch are hardware.
Software (program) consists of instructions that control computer.
Data can be text, numbers, sounds, and images that computer manipulates.
The role of input devices is to accept instructions and data from the user or
other computers.
Storage devices hold data and programs permanently, even when computer is
turned off.
Flash drive is a small, portable memory card that plugs into USB (Universal
Serial Bus) port.

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Exercise

1. Answer the following questions:

a) What is Computer Hardware? Give any three examples.
b) List the four parts of a complete computer system.
c) List the different units of computer hardware.
d) What are the two most common input and output devices?
e) What is CPU? List its sections.
f) Define ALU.
g) Write the use of CU in the computer system.
h) What is the output unit?

2. Fill in the blanks:

a) All the parts of computer that we can see, touch, and feel are known as ........
b) Keyboard is an example of .......................... device.
c) A device that holds a disk is called a .......................... .
d) .......................... can not be touched or felt.
e) There are .......................... sections in CPU.

3. Mark a tick (√) for the correct statements and a cross (X) for the
wrong ones.

a) A computer system contains hardware and software.
b) Hardware cannot be touched and felt.
c) Software is the instructions that are given to the computer to do

some work.
d) The input unit of the computer system is used for displaying data

and instructions given to the computer.
e) ALU can perform only arithmetic operations.
f) The output unit displays the results of processing in a human

understandable language.

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4. Write the full form:

a) CPU b) ALU c) ROM d) AU
g) RAM
e) DVD f) MU

5. Match the following: Group B
a) stores data and program permanently
Group A b) stores data and program temporarily
c) controls entire computer system
i) Input Unit d) displays the result
e) helps to enter data and instruction
ii) Output Unit

iii) Memory Unit

iv) Hard Disk

v) Control Unit

Activity

Ask your teacher to tell you about the hardware and software being used in
your computer lab. Write their names and uses.

......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................

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

12
3

4

5

ACROSS Computer programs
3 Stores data and programs
4 Input unit
5

DOWN Port
1 Physical components of a computer
2

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Lesson Introduction to
Computer Software
3

Software is a set of instructions that makes the computer perform specific
tasks. In other words, software tells the computer what to do: without the
instructions, computer cannot do anything at all. The term program refers
to any piece of software that helps computer to perform specific tasks. Some
programs exist primarily for the computer’s use to help it perform tasks and
manage its own resources. Other types of programs exist for users, enabling
them to perform tasks such as creating documents. Thousands of different
software programs are available for use on personal computers. Some of the
software we learn in our school curriculum are Microsoft Word, Excel,
PowerPoint, MS-Paint, Adobe Photoshop, Microsoft Windows, etc.

Computer Softwares

Types of Software

Most of the softwares fall into two major categories:
i) System software
ii) Application software

I) System software

System software is any program that controls hardware. It can be used
to maintain computer in some way so that it functions more efficiently. Some

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commonly known types of system software are:

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

a) Operating System

An operating system tells computer how to use its own components. The
examples of operating systems are Windows, the Macintosh Operating
System, and Linux. An operating system is essential for any computer
because it acts as an interpreter among the hardware, application programs,
and the user. When a program wants the hardware to do something, it
communicates through the OS. Similarly, when we want the hardware to
do something, such as copying or printing a file, the request is handled by
the OS.

b) Language Translators

Language translators transform the instructions prepared by
programmers in a programming language into a form that can be interpreted
and executed by a computer system.
There are three types of language translators.
Assembler is a type of language translator that translates programs written
in assembly language into machine or low level language.
Interpreter is a type of language translator that translates programs
written in high-level language (human language) line by line or statement
by statement into machine language.
Compiler is a type of language translator that translates programs written
in high level language into machine language in a single operation.

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c) Utility Software

Utility is a program that makes the computer system easier to use or
performs highly specialized functions. Utilities are used to manage disks,
troubleshoot hardware problems, and perform other tasks that the operating
system may not be able to do on its own. Such operations include formatting
disk, taking backup of files, recovering of lost data and file, removing
viruses, etc. Anti-virus, Archive, Backup, WinZip, Register Cleaner, Disk
defragmenters, etc. are some examples of utility software.

Antivirus WinRar WinZip Disk Defragmenter Cleaner

II) Application software

Application software tells computer how to accomplish specific tasks,
such as word processing or drawing for the user. Thousands of applications
are available for many purposes and for people of all ages. Some of the major
categories of these applications include:

Application software

Word processing: softwareforcreatingtext-baseddocuments,
such as newsletter or brochures.

Spreadsheet: software for creating number-based
documents, such as salary sheet, budgets.

Database management: software for building and manipulating
large sets of data, such as the names,
address, and phone numbers.

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Presentation programs: softwares for creating and presenting
electronic slide shows.

Graphics programs: softwares for designing, illustrations or
manipulating photographs, movies or
animations.

Multimedia: software for authoring applications for
building digital movies that incorporate
sound, video, animation and interactive
features.

Entertainment and education:

These softwares, are interactive. They use
multimedia.

Web design: They are tools and web browsers, and other
internet applications such as newsreaders
and e-mail programs.

Games: They are single player and many of which
can be played by several people over a
network or the Internet.

POINTS TO REMEMBER

Software is a set of instructions that makes the computer perform specific
tasks.

The two primary categories of software are system software and application
software.

The operating system tells the computer how to interact with the user and
how to use the hardware device attached to the computer.

Application software tells the computer how to accomplish tasks the user
requires.

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xercise

1. Answer the following questions:

a) What is software?
b) What are the main types of software?
c) Differentiate between application software and system software.
d) Give four examples of computer software.
e) What are language translators? List their types.
f) Define utility software with suitable examples.
g) What is application software?
h) What is word processing software? Give some examples.

2. Put the following things in the correct column:

Mouse, Speaker, Windows, MS-Word,
Monitor, MS-Paint,
Printer, Notepad, Headphones, Google Chrome,
Plotter, Light pen,
Hard disk, PowerPoint, Track ball, Adobe Page Maker
MS-Excel
Typing Tutor, DVD,

Linux, Scanner,

Bar Code Reader, Adobe Photoshop,

Hardware Software

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3. State whether the following statements are True or False:

a) Computer software is a collection of programs.
b) System software is the collection of programs that controls

and manages all the operations of the computer.
c) Interpreter translates programs written in high level language

into machine language in a single operation.
d) Application software provides platform to run other software

programs.

e) MS-Paint is an example of application software.
f) In the absence of an operating system, computer cannot perform

any task.
g) Utility software is a system software designed to care and

maintain the computer.

4. Match the following: Group B

Group A

a) System Software i) takes care and maintains the computer.
b) Assembler ii) translates program line by line
c) Utility Software iii) general purpose software
d) Packaged Software iv) controls overall operations of computer
e) Interpreter v) translates assembly language

Lesson LAB

1. What kind of software is installed on your computer? To find out, all
you have to do is turn on your computer. After it starts, you should see
a collection of icons-small pictures that represent the programs and
other resources on your computer.

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Lesson

4 Input and Output Devices

A personal computer would be useless if you could not interact with it
because the machine could not receive instructions or deliver the results of
its work. Input unit or device accepts data and instructions from the user
or from another computer system (such as computer on the Internet). The
most common input device is the keyboard.
An input device does exactly what its name suggests, it enables us to enter
information and commands into the computers. The most commonly used
input devices are the keyboard and the mouse. If we buy a new personal
computer, it will include a keyboard and mouse unless we specify otherwise.
Other types of input devices are available as well, such as a microphone,
webcam, joystick, scanner, etc. Output devices return processed data to
the user or to other computer system.

The Keyboard

The keyboard is one of the first peripherals used with computers, and it is
still the primary input device for entering text and numbers. A standard
keyboard includes about 104 keys: each key sends a different signal to the
CPU. Keyboards come in many styles. The various models differ in size,
shape, and feel.

Function keys Enter key Numeric keys

Shift key Spacebar Arrow keys
Alphabet keys

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The keyboard consists of many keys. It looks like a typewriter.
A key is a small button which has got a character printed on it. The
character can be a letter, number, or symbol. On pressing a key, the
character printed on the key gets typed. It then appears and functions on
the monitor’s screen.
There are different types of keys on a keyboard.
These keys can be divided into:

Alphabet keys

Alphabet Keys

The Alphabet keys are used to type text.
There are 26 alphabet keys.

Numeric keys

Numeric Keys

The numeric keys are used for typing numbers.
They have the numbers 0-9 written on them.
One set of number keys is found just above alphabet keys.
Another set of number keys is present on the right side of keyboard.

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Function keys

These are keys that are used for special functions. They are marked from
F1 to F12.

Arrow keys

The arrow keys are used to control the cursor. They
are also called the cursor movement keys. When we
want to type text, we notice a small line blinking on
the screen. This is known as cursor.

The arrow keys or the cursor keys are found at
the bottom of the keyboard.

Special keys

Enter key:

The Enter key is used to move the cursor to the next line
while typing.

Caps Lock:

The Caps Lock key is used to type letters in capital.

Shift key

The Shift key is never used by itself. It is used along with
the other keys. When we press on Shift key + any alphabet
key, we get capital letters.

Spacebar

The spacebar key is the longest key on
the keyboard. It is used to put in space
between words.

Delete key

The delete key is used to erase or remove something you have
typed on the right side of cursor.

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Backspace key

The backspace key is also used to erase what you
typed on the left side of the cursor.

Mouse

Mouse is a pointing device. It is used to point or
select different items on the screen by positioning
the screen cursor (arrow-like pointer).
Mouse is used to give instructions to computer. So, it
is also an input device.
A mouse is kept on a mouse pad. It has a ball at the bottom and two or
three buttons in the front. When you move mouse on the mouse pad the
cursor moves on the screen. You can move the mouse on the mouse pad so
that the pointer points at an item on the screen. Then, you can select the
item by pressing the mouse button.

Mouse pointer points

Pressing on the button is called clicking. The different types of mouse clicks
are Click, Double-Click, Right-Click, and Drag and drop.

Click

One click of the Left mouse button is called a left click
or click. A single–click is generally used to select an
item on the monitor.

Single click

Double-Click

Two clicks of the left mouse button are called a double
click. Double-clicking is generally used to open a
window or a program.

Double-clicking the mouse

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Right-Click

One click of the right mouse button is called a right-
click. Right-clicking the mouse shows a list of properties
of the selected item.

Drag and Drop Right click

Drag and drop is used to move an item from one position to another on the
monitor with the help of a mouse.

Drag and drop

Scrolling

Scrolling means to move up and down through a
page. We scroll through a page to see parts that do
not fit on the screen.

The scroll mouse is more in use nowadays. It has Scroll wheel mouse
right and left buttons and a scroll wheel at the
centre. The scroll wheel allows us to move the page
up or down on a computer screen.

These days, we use an optical mouse. It works with laser technology by
sensing the light.

A variety of other input devices work with personal computers. They are
listed below.

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Touchpad

A touchpad is a device for pointing (controlling input
positioning) on a computer display screen. It allows
the user to move a cursor with their finger. It can
be used in place of an external mouse and is usually
found on a laptop computer. A touch pad works by
sensing the user's finger movement and downward
pressure.

WebCam

A webcam is a small digital video camera directly or
indirectly connected to computer or a computer network.
Webcams come with software that needs to be installed on
the computer to help users record video on or stream it
from the Web.

Microphone

Microphone is an input device. It allows us to input voice
messages like speeches, singing, music of instruments, and
other sounds into computer.

Joystick

A joystick is an input device. It is used to play computer games
by moving things around the screen. It inputs the player’s
commands into the computer games.

Scanner

A scanner is an input device that scans documents, such
as photographs and pages of text.

Touch Screen

A touch screen is a computer display screen. It is also
an input device. The screens are sensitive to pressure:
a user interacts with the computer by touching
pictures or words on the screen.

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Barcode reader

Bar code readers are one of the most widely used input
devices, which are commonly found in supermarkets
and department stores. These devices read bar codes,
which are patterns of printed bars that appear on
product packages.

Output Devices

Monitor and Printer are the most common
output devices. A monitor displays the result
of the task performed by computer. The result
displayed on the screen of monitor is called
soft copy of the output.
A printer is used to take printouts as permanent
documents on paper. This is called the hard
copy of the output.
Some other output devices are Plotter, Speaker, Headphones, etc.

Speakers Headphones Plotter

Monitor

A monitor looks like a TV screen. It is also called a
Visual Display Unit (VDU). The front part of the
monitor is called a screen. It displays on the screen,
words or numbers you type, on the keyboard or
pictures you draw with the mouse. Most monitors
used nowadays are color monitors.

You can see the result of computer on the monitor.
This result is known as soft copy output. Monitor
shows the work that the CPU does.

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A monitor can be used to watch movies and television programs as well. It
is connected to the CPU with a wire.
At present most of the monitors are color monitors. The CRT (Cathode Ray
Tube) monitor, LCD (Liquid Crystal Display) monitor, and LED (Light-
Emitting Diodes) monitor are available in the market.

CRT Monitor LCD Monitor LED Monitor

Printer

A printer is used to print what we see on the screen on a sheet of paper.
This is called printout. The output printed in the printer is known as hard
copy output.

There are various types of printers in market. The commonly used printers
are

Dot Matrix Printer Inkjet Printer Laser Printer

Dot Matrix Printer Inkjet Printer Laser Printer
Projector
Projector

A projector is an output device that can take images
generated by a computer and reproduce them onto a
screen, wall, or other white surface. You could use a
projector to show a presentation on a large screen so
that everyone in a room can see it.

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Speakers Speakers

Speakers are used to listen to songs, music or any
sound processed in computer. They are very useful
when we play games, listen to songs, and watch
movies on computer.

Headphones

Headphones are also used for listening to songs, music
or any sound processed in computer without disturbing
others.

Headphones

POINTS TO REMEMBER

A standard computer keyboard has about 104 keys.
Mouse is a pointing device that lets you control the position of a graphical
pointer on the screen without using the keyboard.
Using the mouse involves five techniques: pointing, clicking, double-clicking,
dragging, and right-clicking.
Touch-screen systems accept input directly through the monitor.
Joystick is a special input device that accepts the user’s input to play a game.
Scanners convert printed images into digitized formats that can be stored and
manipulated in computers.
Microphones can accept auditory input.
Computer monitors are roughly divided into three categories: CRT, LCD, and
LED.

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The commonly used printers are dot matrix, inkjet, and laser printer.

Projector is a portable device that connects to a PC.

Many people prefer to listen to audio output through headphones or a headset,
instead of using speakers.

Exercise

1. Mark a tick (√) for the correct statements and a cross (X) for the
wrong ones.

a) A keyboard is an input device.
b) In most programs, we can press F1 key to get help.
c) Joystick is an output device.
d) Mouse is also called a pointing device.
e) Optical type of mouse uses reflected light to measure its movements.
f) Alphabet keys are used to enter numbers.
g) Joystick adds to computer games more fun.
h) Speakers are used to listen to songs, music.

2. Use the words given below to fill in the blanks.

(Output monitor keyboard hard copy printer wire)

a) A ...................... is used to input data and instructions.

b) The ...................... and ...................... are output devices.

c) The output printed by printer is known as ...................... output.

d) A projector is an ...................... device.

e) Monitor is connected to the CPU by a ...................... .

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3. Answer the following questions.

a) What is an input device? Name any two input devices.
b) Write one function each of Caps Lock and Shift keys.
c) What does the term drag and drop mean and how do you do it?
d) What is a touch screen?
e) What is joystick?
f) Give difference between soft copy output and hard copy output.
g) What is a monitor? What are the three types of monitors?
h) What is a printer? What are the different types of printers?
i) What is a speaker?

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

12

4 3
7
5
6

8

ACROSS Move up and down through a page DOWN Write in capital letters
1 Longest key on the keyboard 2 Hard-copy output
4 Soft copy output 3 Pointing device
6 Move the cursor to the next line 5
7 Audio output
8

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Lesson

5 Storage Devices

Introduction

Computer stores data or information using several different methods.
Storage Devices are physical parts of computer system that store data,
instruction, and programs either temporarily or permanently. Computer
has many types of data storage devices. Some of them can be classified as
the removable data storage devices and the others as the non-removable
data storage devices.

Memory is the workspace for the computer’s processor. It is an essential part
of computer that stores unprocessed and processed data. Computers use
different types of memory, but the two most important types are Primary
Memory and Secondary Memory.

Primary Memory

Primary memory of computer is also known as its main memory. It is
used to hold pieces of program instructions and data, intermediate results
of processing, and recently produced results of those job(s) on which the
computer is currently working. However, primary storage can hold
information only while computer system is on. It operates at a very high
speed. It is also expensive. As soon as the computer system switches off or
resets, the information held in primary storage is erased.

a) Random Access Memory (RAM)

The most common type of memory
is called Random Access Memory
(RAM). RAM holds data and program
instructions while the CPU works with
them. When a program is launched, it
is loaded into it and run from memory.
As the program needs data, it is loaded
into memory for quick access. When

Random Access Memory (RAM)

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new data is entered into computer, it is also stored in memory but only
temporarily. RAM is volatile, meaning that it loses its contents when the
computer is shut down or if there is power failure. Therefore, RAM needs a
constant supply of power to hold its data. For these reasons, you should save
your data files to a storage device frequently, to avoid losing them at power
failure.
RAM has a tremendous impact on the speed and power of computer,
generally, the more RAM a computer has, the faster it can perform certain
tasks. Today, personal computers generally have at least 4 Giga Bytes of
random access memory. Many newer systems feature even 32 GB or more.

b) Read-Only Memory (ROM) ROM

Unlike RAM, Read Only Memory (ROM)
permanently stores its data. ROM is called
non-volatile memory because it never loses
its contents. ROM holds instructions that
computer needs to operate. Whenever the
power button is turned on, it checks ROM
for directions that help it start up, and give
information about its hardware devices.
There are three types of ROM: Programmable
Read Only Memory (PROM), Erasable
Programmable Read Only Memory (EPROM),
and Electrically Erasable Programmable
Read Only Memory (EEPROM).

Secondary Memory

When you work on computer, it stores information temporarily. As soon as
it is switched off, the information is lost. So, you need a place where you can
store data on a long-term basis. This ensures that data can be used as and
when required.

The memory where the programs and data are stored on a long-term basis is
called secondary memory. It is needed in computers because the programs
and data in the primary memory are lost when the computer is switched off.
The most commonly used devices for secondary memory are: Hard Disk,
Solid State Drives, Compact Disc, Flash Drive, etc.

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Hard Disk

A hard disk is a non-volatile computer storage
device containing magnetic disks or platters
rotating at high speed. It is a secondary storage
device used to store data permanently. When you
save data or install programs on your computer,
the information is typically written to your hard
disk. The hard disk is a spindle of magnetic disks,
called platter that record and store information.
Because the data is stored magnetically, the Hard Disk

information recorded to the hard disk remains
intact even after we turn computer off. This is an important distinction
between the hard disk and RAM, or memory, which is reset when the power
is turned off in computer. The hard disk rotates while recording data. This
rotation speed is measured in the unit of revolutions per minute (rpm). The
normal speed of hard disks is 3600 to 7200 revolutions per minute. Storage
Capacity of hard disks varies from 20 MB to several Gigabytes to Terabytes
like 80GB, 160GB, 1TB, 2TB, 4TB, etc.

Internal structure of Hard Disk

Optical Disc

The most popular alternatives to magnetic storage systems are optical
systems, including CD-ROM, DVD-ROM, and their variants. These devices
fall into the category of optical storage because they store data on a
reflective surface so that it can be read by a beam of laser light. A laser
uses a concentrated, narrow beam of light, focused and directed with lenses,

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prisms, and mirrors. The optical disc became the preferred medium for
music, movies, and software programs because of its many advantages. It is
compact, lightweight, and durable.

Optical Disc Technology (land, pit) Compact Disc

Compact Disc (CD): DVD

Compact Disc is a type Read Only Memory which stores 43
a wide variety of information. Its main advantage is
that it is portable and can hold a large amount of data.
CDs will probably continue to be popular for music
recording and playback. A standard CD can store about
80 minutes of audio or 700 MB of data.

Digital Versatile Disc (DVD):

Digital Versatile Disc is an optical disc that can store
very large amount of data. The working principle of
DVD is similar to a compact disc; still, it can store
larger amounts of data. A DVD can store 4.7 GB to
17 GB of data. DVDs are generally used to store very
large multimedia presentations and movies that
combine high quality sound and graphics. DVD drives
are now standard equipment on many new personal
computers. Users not only can install programs and
data from their standard CDs, but they can also watch
movies on their personal computers by using DVD.

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Blu-ray Disc

A Blu-ray disc is replacing DVDs nowadays. It has more than five times
storage capacity than that of DVDs. High quality sound music, games; and
movies can be stored in such types of disc.

Pen / Flash Drive

It is a small, portable device that can be used to
store, access, and transfer data. We can read,
write, copy, delete, and move data from computer
to pen drive or pen drive to computer. It comes in
various storage capacities like 8GB, 16GB, 64GB,
1TB, or more. It is popular because it is easy to
use and small enough to carry in pocket. It is
smaller than the size of a car key. This device is
plugged into the USB port of computer and the USB Pen / Flash Drive

computer recognizes it and starts to communicate with it. It is also called
USB or flash drive.

POINTS TO REMEMBER

Storage devices are physical parts of a computer system that stores data,
instruction, and programs either temporarily or permanently.
Memory is the workspace for the processor in computer. It is an essential part
of computer that stores unprocessed and processed data.
Primary memory of computer is also known as its main memory.
The most common type of memory is called Random Access Memory (RAM).
It is volatile.
RAM holds data and program instructions as the CPU works with them.
The most common units of measure for memory are the byte, kilobyte,
megabyte, gigabyte, and terabyte.
ROM is called non-volatile memory because it never loses its contents.
ROM holds instructions that the computer needs to operate with.

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Storage devices hold data and programs permanently, even when the computer
is turned off.

The two primary categories of storage devices are magnetic storage and
optical storage.

The primary types of optical storage are compact disc and digital video disc.

CD-ROM uses the same technology as a music CD does: a laser reads lands
and pits on the surface of the disk.

Standard CD-ROM discs can store up to 700 MB. Once data is written to the
disc, it cannot be changed.

DVD-ROM technology is a variation on the standard CD-ROM. DVDs offer
capacities up to 17GB.

Blu-ray disc has more than five times storage capacity than DVDs.

bFlash drivesbare often used for storage, data back-up and transfer of files.

Compared to CDs, flash drives are smaller and faster. They have significantly
more capacity. They are more durable than CDs.

xercise 45

1. Answer the following questions:

a) What is memory? List its types.
b) Define primary memory?
c) Why is RAM called volatile memory?
d) Write some differences between RAM and ROM.
e) What is secondary memory? Give some examples.
f) Define Hard Disk.
g) What is optical disk? Write its types.
h) What is pen drive?

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2. State whether the following statements are True or False:

a) Computer has many types of data storage devices.
b) Basically, computer memory is divided into two types.
c) ROM is temporary in nature.
d) RAM is permanent in nature.
e) The programs stored on the secondary memory cannot be used later.
f) Hard disk cannot store large amount of data.
g) Hard disk is generally fitted inside the system unit.
h) Flash drive is small enough to be carried in a pocket.
i) DVD is an old technology as compared to CD.
j) CDs will probably continue to be popular for music recording

and playback.

3. Select the best answer of the following:

i) Which of the following devices stores instructions that help computer start up?

a) Joystick b) RAM c) ROM d) monitor

ii) Which of the following units represents the large amount of data?

a) kilobyte b) terabyte c) gigabyte d) megabyte

iii) Generally, .................... cannot be removed from the computer.

a) mouse b) keyboard c) hard disk d) pen drive

iv) Which type of disc can store up to 17 gigabytes of data?

a) compact disc b) optical disc c) digital video disc d) none of these

v) A ....................... is an example of a magnetic storage device.

a) flash memory b) hard disk c) CD d) DVD

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4. Give full forms of the following abbreviations:

a) ROM b) RAM c) CD

d) DVD e) USB f) EPROM

g) GB h) TB i) RPM

5. Match the following: Group B

Group A

i) Primary Memory a) Popular for music recording.

ii) Hard Disk b) Volatile memory.

iii) Pen Drive c) Non-volatile memory

iv) ROM d) Plugged into the USB port of the computer.

v) CD e) Stores data and programs for future use
permanently.

vi) RAM f) Stores data and programs temporarily.

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

1 23

4

ACROSS Small portable device
1 None volatile memory
4

DOWN Data stored magnetically
2 Volatile memory
3

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Lesson Introduction to Operating
System (MS-Windows)
6

INTRODUCTION

When we start computer, the first software loaded is an operating system.
An Operating System acts as an intermediate between the user and
the machine. It provides a working environment to the user. Microsoft
Windows is the most commonly used operating system. Linux, Ubuntu
and Mac OS are some other operating systems. In this chapter, we learn
about the Windows 10 in detail. Windows 10 has evolved from older versions
of Windows (95, 98, Me, NT, 2000, XP, Vista, 7, 8).

Why do we need an Operating System?

It manages computer hardware like CPU, Memory, Hard disk, etc.
It allows us to communicate with computer.
Without an operating system, computer is useless.
It acts as a manager of computer system.

Advantages of Windows Operating System

Windows is an Operating System which supports the GUI (Graphical User
Interface) environment. All commands can be executed easily and efficiently
at a click of mouse. Some of its advantages are:

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a) GUI (Graphical User Interface):

It is an environment where the user clicks on a visual screen that has
icons, windows, and menus, by using a pointing device, such as mouse.

b) Easy to use and learn:

Working with Windows is easy as it just requires a few mouse clicks to
do your work. You do not need to remember and type the commands using
Keyboard.

c) Multitasking:

It performs multiple tasks at one time. For example, you can create
documents as well as listen to songs.

?KDind oYwou The Graphical User Interface (GUI) was
first introduced to the public by Apple
with the Macintosh in 1984.

What is MS-Windows?

MS-Windows is the most popular and widely used operating system
developed by Microsoft. Windows 10 is the newest version of the windows
operating system. Some previous versions are Windows XP, Windows 7 and
Windows 8. The windows operating systems are GUI (Graphical User
Interface) based operating systems.

?KDind oYwou The first Windows operating system
known as Microsoft Windows 1.0 was
released on November 20, 1985.

The Desktop

When we switch computer on, the first screen that we see is desktop after
the welcome message. It contains icons, program or file shortcuts, start
button and taskbar needed for accessing the available programs.

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