STEPS:

1. Open Blogger.com and login.

2. Go to settings

3. Go to "Others"

4. Here you will find the option to delete the blog.

5. Select delete blog option

6. Click on delete this blog.

7. Select your blog from the deleted blogs.

8: Click on permanently delete.

THE BLOG HAS BEEN DELETED

Step # 1: Search Blogger.com and open blogger.

Open google chrome and search blogger.com. And open blogger. 

Step # 2:  Now select the blog you wanna delete. from your blogger account.

select the blog you want to delete from your blogger account.

if you have only 1 blog then you don't need to select it you can skip this step.

Step # 3: Go to settings.

In the right sidebar you will find settings (as shown in the image below)

Step # 4: Click on "other"

In the sub menu of settings you will find the option "others" click on it.

Step # 5: Select delete blog option.

here you will find the option to delete your blog ( as shown in the image below)

Step # 6: Click on delete this blog.

If you want to download your blog for later use or to export it to anywhere else you can click on the download blog button.

and if you dont want it simply just click on "delete thid blog" 
you can restore your blog within 90 days after deleting it after 90 days it will be deleted permanently .

if you want to delete it permanently now then follow the next step. 

Step # 7: Select your blog from the deleted blogs.

After deleting your blog you will find your blog in the deleted blog option.

 you can restore your blog within 90 days after deleting it after 90 days it will be deleted permanently .

if you want to delete it permanently now then click on the blog name in the deleted blog option.

Step # 8: Click on permanently delete.

now click on permanently delete and after that your blog will be deleted permanently.

THE BLOG HAS BEEN DELETED

As you can see the blog has been deleted permanently

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 5. Data Representation
Define Data.

Ans: Data: A computer program is a collection of data, which can be interpreted as
instruction. Data refers to a collection of organized information, usually the results of
experience, observation or experiment, or a set of premises. This may consist of
numbers, words, or images, particularly as measurements or observation of a set of
variables. Or Data is any collection of facts or figures. The data is the raw material
to be processed by a computer. Names of students, marks obtained in the examination,
designation of employees, addresses, pictures, photographs, drawings, charts and
maps can be treated as data.
Q:

What are the types of data?

Ans: Types of Data: The collection of information is called data. Data could of different
types depending upon their use and requirement within the processing concerned.
Mainly, data is divided into two types:
1. Numeric Data
2. Character Data
Numeric Data: The data, which is represented in the form of numbers, is known as
Numeric data. This includes 0-9 digits, a decimal point (.), +/- sign and the letters E”
or “D”. The numeric data is further divided into two groups:



Integer Data: Integer data is in the form of whole numbers. It does not
contain a decimal point; however, it may be a positive or a negative number.
E.g. 2543, -60, 0, +72 etc.
Real Data: Real data is in the form of fractional number. It contains a decimal
point. It can also be positive or negative number. Real data is further divided
into two types:
 Fixed pint data: It includes digits (0-9), a decimal point, +/- sign. E.g. 23.07, .11245, +92.786, 17.12 etc,
 Floating point data: It is composed of very big or very small numbers,
which cannot be expressed in normal way e.g. it includes time period for
chemical reaction etc. E.g. charge of electron 1.602x10-19 coulomb, Velocity
of light in m/sec 2.9979x108

Character Data: Character data falls into two groups: i) String data, ii) Graphical
data.




String Data: String data consists of the sequence of characters. Characters
may be English alphabets, numbers or space. The string data is further divided
into two type:
 Alphabetic Data: The data, which is composed of English alphabets, is
called alphabetic data. For example, names of people, names of places etc.
(Ahmed, AHMED, Karachi, chair etc)
 Alphanumeric Data: The data that consists of alphabets as well as
numerals and some special characters is called alphanumeric data. Address,
Employee code, etc are alphanumeric data. For example, 103, Block No.2,
E103, etc
Graphical Data: Pictures, drawing, photographs and maps are considered as
data. Scanner is used to enter this type of data into computer.
20

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 5. Data Representation
Define information.

Ans: Information: Information is a useful, meaningful and organized form of data.
Computer converts data into information after processing. The output or result of
compute is called information. For example: a mark sheet, a utility bill, a printed
cheque, etc.
Input (Data)

Q:

Processing

Output (Information)

Explain Number system?

Ans: Number System: The number system is the system of counting and calculation.
Number system is based on some characters called digits. Each number is made up of
these characters. The number of digits a system uses is called its base or radix. For
example, the number system we use in our daily life is called Decimal system. Its base
is 10(As the name “Deci” implies.) which mean that it uses 10 digits (i.e. 0-9). There
are four types of number systems used in computer operations.
i)
Decimal ii) Binary
iii) Octal
iv) Hexadecimal
Q:

What are type of number system? Explain in details.

Ans: Type of Number System: There are four types of number systems used in
computer operations.
i)
Decimal ii) Binary
iii) Octal
iv) Hexadecimal
Decimal Number System: We use this number system in our daily life for counting
and calculations. This system uses 10 different symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9
which are called Arabic numerals. The decimal number system is also called the base
10 system. Each of the ten digits, 0 to 9, represents a certain quantity.
The value that the digits represent depends on the weight, or position they hold.
The weights are based on the powers of 10 as shown

4th
3rd
103=1000 102=100

2nd
101=10

1st
100=1

Position
Weight

The Binary system: The binary numeral system, or base-2 number system, is a
numeral system that represents numeric values using two symbols, usually 0 (for
OFF) and 1(for ON). The binary system is ideal for internal working of electronic
computer. Computer circuitry represents data in pattern of ON or OFF states of electric
current. The positional weights for the binary system are based on the powers of 2.
The weights for the first four positions are given as under:

4th
23=8

3rd
22=4

2nd
21=2

1st
20=1

For example, 100112 can be represented in decimal as:
100112
= 1 x 24 + 0 x 23 + 0 x 22 + 1 x 21 + 1 x 20
= 1 x 16 + 0 x 8 + 0 x 4 + 1 x 2 + 1 x 1
= 16 + 0 + 0 + 2 + 1
= 19
21

Position
Weight

Sir Sadiq’s computer notes for class IX
Chapter no 5. Data Representation
The Octal System: Octal is a Latin word used for eight (8). Octal has eight
fundamental digits as, 0, 1, 2, 3, 4, 5, 6, 7, so the base of this system is 8. The weights
of digit position are successive powers of 8 as under.
For example 3528 can be represented in decimal as:
3528
= 3 x 82 + 5 x 81 + 2 x 80
= 3 x 64 + 5 x 8 + 2 x 1
= 192 + 40 + 2
= 23410

Hexadecimal: Hexadecimal means 16, therefore this is a base-16 number system. It
has 16 fundamental digits. The first ten digits are same as decimal (0-9) and the rest
of the 6-digtis are the first six letters of English alphabet (A, B, C, D, E, and F). The
letters A through F represents the decimal numbers 10 through 15. This system is often
used in programming as a shortcut to the binary number system. The weights used in
the hexadecimal system are the successive powers of 16. The weights of the first four
digits position are as under:

4th
3rd
163=4096 162=256

2nd
161=16

1st
160=1

Position
Weight

For example, 3AC816 can be represented in decimal as:
3AC816
= 3 x 163 + A x 162 + C x 161 + 8 x 160

Q:

= 3 x 4096 + 10 x 256 + 12 x 16 + 8 x 1
= 12288 + 2560 + 192 + 8
= 1504810

Which number system computer uses for processing of data and why?

Ans: The Binary Number system is used for processing of data. The binary numeral system,
or base-2 number system, is a numeral system that represents numeric values using
two symbols, usually 0 and 1. More specifically, the usual base-2 system is a positional
nation with a radix of 2. Owing to its straightforward implementation in electronic
circuitry, the binary system is used internally by virtually all modern computers.
Q:

What are codes? How many types of “codes” are used in computer system?

Ans: Codes: When number, letters or words are represented by special group of symbols,
they are being encoded and the group of symbols is called “code”. The codes include
Binary codes, Binary-coded-decimal code (BCD), and alphanumeric coded.
Alphanumeric codes include ASCII and EBCDIC.
Q:

What is ASCII code?

Ans: ASCII: The American standard code for information interchange (ASCII) pronounced
as “askee” is a universally accepted alphanumeric code used in most computer and
other electronic equipment. Most computer keyboards are standardized with ASCII.
When we enter a letter, a number, or control command, the corresponding ASCII code
goes into the computer. ASCII has 26 characters and symbols represented by an 8-bit
code series. The first 32 codes in the ASCII table represent the control characters that
are not printed or displayed. The other characters are graphic symbols that can be
printed or displayed.

22

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 5. Data Representation
How a flatting-point number is represented in the computer?

Ans: Floating-point Number: The floating-pint number system, based on scientific
notation, is capable of representing very large and very small numbers without an
increase in the number of bits and also for representing numbers that has both inters
and fractional components.
A floating-point number (also known as real number) consists of two parts plus a
sign. The mantissa is the part of a floating-point numbers that represents the
magnitude of the number. The exponent is the part of a floating-point number that
represents the number of places that the decimal point (or binary point) is to be moved.
A decimal number which is, in integer form, is 254,927,200. The mantissa is .2549272
and the exponent is 9. The mantissa is a fractional number and the exponent is the
power of ten. The floating-point number is written as 0.2549272 x 109.
Q:

How 1’s and 2’s complements are represented in computers?

Ans: Complements: The 1’s and 2’s complements of binary numbers permit the
representation of negative numbers. The 1’s of a binary number is formed by changing
all 1’s to 0’s and 0’s to 1’s. The 2’s complement of a binary number is formed by
adding 1 to the least significant bit of 1’s complement. The left-most bit in a signed
binary number is the sign bit, which tells whether the number is positive or negative.
Finding the 1’s complement of a number:
The 1’s complement of a binary number is formed by changing all1’s to 0’s and 0’s to
1’s.
Binary number

10100110

1’s complement

01011001

Finding the 2’s complement of a number:
The 2’s complement of a binary number is formed by adding 1 to the LSB (Least
Significant Bit) of 1’s complement.
2’s complement = (1’s complement) + 1
Example: Find the 2’s complement of 10010111
Binary number
1’s complement
Add 1
2’s complement

10010111
01101000
+
1
01101001

Book Exercises
Q:

Convert the decimal number into Binary?
23

Sir Sadiq’s computer notes for class IX
Chapter no 5. Data Representation
81410=
2
814
2
407
0
2
203
1
2
101
1
2
50
1
2
25
0
2
12
1
2
6
0
2
3
0
2
1
1
81410= (1100101110)2
Q:

Convert the binary number into decimal?
(1100101110)2=

Q:

1x29+1x28+0x27+0x26+1x25+ 0x24+1x23+1x22+1x21+0x20
1x512+1x256+0x128+0x64+1x32+0x16+1x8+1x4+1x2+0x1
512 + 256 + 0 + 0 + 32 + 0 + 8 + 4 + 2 + 0
814
(1100101110)2 = (814)10
Convert the decimal number into equivalent octal number?
75010=

Q:

8
8
8
8

750
93
11
1

6
5
3

75010= (1356)8
Convert the octal number into decimal number?
6558=

Q:

6 x 82 + 5 x 81 + 5 x 80
6 x 64 + 5 x 8 + 5 x 1
384 + 40 + 5
429
6558 = 42910
Convert the decimal number into hexadecimal number?
178010=
178010= (6F4)16

Q:

16
16
16

1780
111
6

4
F

Convert the hexadecimal number into decimal?
(A109)16= A x 163 + 1 x 162 + 0 x 161 + 9 x 160
10 x 4096 + 1 x 256 + 0 x 16 + 9 x 1
40960 + 256 + 0 + 9
41225
(A109)16= (41225)10
24

(15=F)

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 5. Data Representation
Convert the hexadecimal number into binary number & Binary number into
hexadecimal?
Table of Conversion between Binary and Hexadecimal

Q:

Hexadecimal
Binary
Hexadecimal to binary
0
0000
(A35)16=
1
0001
A
3
5
2
0010
1010 0011 0101
3
0011
Ans: 1010001101012
4
0100
5
0101
Binary to hexadecimal
6
0110
(1110100)2=
7
0111
01111
0100
8
1000
7
4
9
1001
Ans: 7416
A
1010
B
1011
C
1100
D
1101
E
1110
F
1111
Convert the Octal number into binary number & Binary number into octal?
Table of Conversion between Binary and Hexadecimal
Octal
0
1
2
3
4
5
6
7

Binary
000
001
010
011
100
101
110
111

Octal to binary
(453)8=
4
5
3
100 101 011
Ans: 1001010112
Binary to octal
(1110100)2=
001 110
1
6
Ans: 1648

100
4

Q:

Convert the octal numbers into hexadecimal?
117
Ans: Convert first into binary then into hexadecimal by yourself.
Q:

Convert the hexadecimal numbers into octal number?
44CD
Ans: Convert first into binary then into octal by yourself.
Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq, smsadiqnoori@gmail.com

25

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 6. Boolean Algebra
What is Boolean algebra?

Ans: Boolean algebra: Boolean algebra was named after George Boole, who first
defined an algebraic system of logic in the mid-19th century. Boolean algebra is a
convenient and systematic way of expressing and analyzing the operations of logic
circuits. It is a mathematical system for formulating logical statements with symbols.
It is applied in the design and analysis of digital systems. It provides the operations
and the rules for working with the set {0,1}. Electronic and optical switches can be
studied using this set and the rules of Boolean algebra. Boolean algebra is now being
used extensively in designing the circuits used in computers.
Q:

What are the Rules of Boolean algebra used to simplify an expression?

Ans: Rules of Boolean algebra:
Rule
Rule
Rule
Rule
Rule
Rule
Rule
Q:

1:
3:
5:
7:
9:
11:
12:

A+0 =A
Rule
A.0 =0
Rule
A+A =A
Rule
A+A=1
Rule
A
=A
Rule
A+A.B = A + B
(A+B) (A+C) = A+BC

2:
4:
6:
8:
10:

A+1 =
A.1 =
A.A =
A. A =
A+A.B =

1
A
A
0
A

Define Boolean constants and variable.

Ans: Boolean Constant: Boolean algebra used binary values 0 and 1 as Boolean
constant.
Variable: The variables used in the Boolean algebra are represented by letter such
as A,B,C, x,y,z, etc, with each variable having one of two and only two distinct
possible values 0 and 1.
Q:

Define Truth table.

Ans: Truth Table: The truth table is a systematic listing of the values for the dependent
variable in terms of all the possible values of independent variable. It can also be
defined as a table representing the condition of input and output circuit involving two
or more variables. In a binary system, there is 2n number of combinations, where n is
the number of variables being used. A truth table is a table of all possible
combinations of the variables.
Q:

How many basic logical operators used in Boolean algebra?

Ans: Logical Operator: There are three basic logical operations used in Boolean algebra.
1. ÖR” Operator is represented by a “+” sign. It is used for logical addition or
Boolean Sum.
2. ÄND” Operator is represented by a “.”. It is used for logical multiplication.
3. “NOT” Operator is represented by a prime (‘) or bar (-) on the variable. It is
used for complement operation.

26

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 6. Boolean Algebra
Define OR operator.

Ans: OR Operator: OR operator is represented by a “+” sign. It is used for logical
addition or Boolean Sum. The “+” symbol or OR operation is used by listing all
possible combinations of, for example, A and B and the resulting value of C in the
equation
A + b = C. It is read as “A OR B is equal to C”.
It may be noted that as there are two variables A and B so only 4 (2 n = 22)
combinations of inputs are possible as shown in the Truth Table.
INPUTS
OUTPUT
A
B
A+B=C
0
0
0
0
1
1
1
0
1
1
1
1
Q:

Define AND operator.

Ans: AND Operator: This operation is represented by dot “.” or the absence of an
operator. It is used for logical multiplication. The AND operation is defined by listing
all possible combinations of, for example, A and B and the resulting valued of C in
the equation
A . B = C or AB = C read as Ä AND B is equal to C”.
The truth table for logical AND operation is shown in the table.
INPUTS
A
0
0
1
1

B
0
1
0
1

OUTPUT
A.B=C
0
0
0
1

Q: Define NOT operator.
Ans: NOT Operator: This operation is represented by a prime (‘) or bar (-) on the
variable. It is used for complement operation. For example, A (read as A bar) means
complement of A or NOT A.
INPUTS
A
0
1
Q: What are the Laws of Boolean algebra?

OUTPUT
A
1
0

Ans: Laws of Boolean algebra: There are three basic laws of Boolean algebra are the
same as in ordinary algebra.
1) Commutative Laws 2) Associative Laws 3) Distributive Laws

27

Sir Sadiq’s computer notes for class IX
Chapter no 6. Boolean Algebra

Q:

Commutative Laws:
i.
The Commutative law of Addition for two variables is written as. A + B = B
+ A. The Law states that the order in which the variables are ORed (added)
makes no difference. Remember that in Boolean algebra addition and OR
operation are same.
ii. The commutative law of multiplication for two variables is written as A . B
= B. A. This law states that the order in which the variables are ANDed
(multiplied) makes no difference.
Associative Laws:
i.
The Associative law of addition is written as follows for three variables. A +
(B + C) = (A + B ) + C. This law
states that when ORing more than two variables, the result is the same
regardless of the grouping of the variables.
ii. The Associative Law of multiplication is written as follows for three
variables. A(BC) = (AB)C. This law states that it makes no difference in
what order the variables are grouped when ANDing more than two
variables.
Distributive Law:
i.
The distributive law is written for three variables as follows. A(B + C) = AB
+ AC. This law states that ORing two or more variables and then. Anding
the result with a single variable is equivalent to ANDing the single variable
with each of the two or more variables and then ORing the products. The
distributive law also expresses the process of factoring in which the
common variable A is factored out of the product terms.
AB + AC = A(B + C)
What are the Standard forms of Boolean Expressions?

Ans: Standard form of Boolean Expression: All Boolean expressions regardless of
their form can be converted into either of two standard forms.
1.
2.

The Sum-of-Product (SOP)
The Product-of-Sum (POS)

The Sum-of-Product (SOP):
When two or more products terms are summed by Boolean addition, the resulting
expression is a sum-of-product (SOP).
Examples:
A + ABC
ABC + CDE + BCD
AB + ABC + AC
An algebraic expression can be changed into SOP by applying Boolean algebraic
techniques. For example, the expression A(B + CD) can be converted to SOP
form by applying the distributive law:
28

Sir Sadiq’s computer notes for class IX
Chapter no 6. Boolean Algebra
A(B + CD) = AB + ACD
Example:
Convert the following expression to SOP form?
(A + B)(B + C + D)
Solution:
(A + B) (B + C + D) = AB + AC + AD + BB + BC + BD
The Product-of-Sums (POS):
When two or more sum terms are multiplied, the resulting expression is a productof-sums (POS).
Examples:
(A + B) (A + B + C)
(A + B + C) (C + D + E) (B + C + D)
(A + B) (A + B + C) (A + C)
Q:

What is Karnaugh Map? How can Karnaugh Map help in simplifying a
Boolean expression?

Ans: Karnaugh Map: Karnaugh map provides a systematic method for simplifying
Boolean expression and if properly used will produced the simplest SOP or POS
expression possible. The Karnaugh map is also known as K-map. It is similar to a
truth table because it presents all of the possible values of input variables and the
resulting output for each value. K-map is an array of cells in which each cell
represents a binary value of the input variables. Karnaugh maps can be used for
expressions with two, three, four and five variables.
K-maps, are often used to simplify logic problems with 2, 3 or 4 variables. 2-variable
Karnaugh maps are trivial but can be used to introduce the methods need to learn.
A
The map for a 2-input OR gate looks like this.
0

B

A

0

Output

Input
B

1

1
1

1

1

A+B

The values of one variable appear across the top of the map, defining the column
values, while the values of the other variable appear at the side, defining the values
of the variable in each row.
Q:

State the Prove Demorgan’s theorem.

Ans: Demorgan’s theorem: The most important logic theorem for digital electronics,
this theorem says that any logical binary expression remains unchanged if we
1.
2.
3.
4.

Change all variables to their complements
Change all AND operations to Ors.
Change all OR operations to ANDs.
Take the complement of the entire expression.
29

Sir Sadiq’s computer notes for class IX
Chapter no 6. Boolean Algebra
DeMorgan, a mathematician who knew Boole, proposed two theorems that are an
important part of Boolean Algebra. They help in simplifying complicated logical
expression.
i)
XY = X + Y
The complement of a product of variable is equal to the sum of the compliments of
the variables.
Proof:
The theorem can be proved by the Truth table:
X
0
0
1
1

Y
0
1
0
1

X.Y
0
0
0
1

X.Y
1
1
1
0

X
1
1
0
0

Y
1
0
1
0

X+Y
1
1
1
0

12
ii)
X + Y = X.Y
The complement of a sum of variables is equal to the product of the complements
of the variables.
Proof:
The theorem can be proved by the Truth table:
X
0
0
1
1

Y
0
1
0
1

X+Y
0
1
1
1

X+Y
1
0
0
0

X
1
1
0
0

Y
1
0
1
0

X.Y
1
0
0
0

Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq smsadiqnoori@gmail.com

30

Sir Sadiq’s computer notes for class IX
Chapter no 7. Computer software

Q: What is software?
Ans:
Software: Software is a general term used for computer
programs. A computer program is a planned, step by step set of
instructions that directs the computer what to do and how to do. OR
computer software is a general term used to describe a collection of
computer programs, procedures and documentation that perform some
task on a computer system. There are two types of software, namely,
System Software and Application software.
Q: Define system software and application software in detail.
System Software: The users interact with the application software
whereas system software enables the application software to interact
with the computer hardware. System software is “background”
software. It includes programs that help the computer manage its
internal resources. System software are of following types:
1. Operating system: An operating system is a set of programs
which starts a computer and allows the users to interact with the
hardware and software present in the computer. Without operating
system, a computer cannot do anything useful. Some of the
popular operating systems used in personal computer are: DOS,
Windows, UNIX, Linux, Solaris, etc.
2. Language Translator: It translates a computer program into
machine understandable form. Language translators are
Interpreter, Compiler and Assembler. Interpreter translates
and executes each program statement one at a time, translation is
required if program is run again. Compiler translates the whole
program at a time and stores translated program on disk. The
Assembler is translator for Assembly language.
3. Data-management software: Data-management software
includes database and file management programs that manage
data for an operating system. They can organize, update and print
data.
4. Editors: Editors allow the user to type-in a program generate text
and make modifications whenever necessary. A program is first
written in an editor and then is compiled.
5. Utility software: These are program that users can purchase as
separate products to perform a wide range of functions. The
programs for these functions are PC-Tools, Scand Disk, Norton Disk
Driver, Antivirus, etc.

30

Sir Sadiq’s computer notes for class IX
Chapter no 7. Computer software

Application software: Application software is programs that help a
user perform a specific job. It enables the computer to produce useful
work such as writing a letter, making a reports and preparing
accounts etc. Application software is further divided into two classes.
1. General purpose application software
2. Special purpose application software
General purpose application software: These are called
packaged software or commercial software. Single software can be
applied to a wide variety of tasks. It includes, M.S Office, Corel Draw,
Inpage, Adobe Photoshop, etc.
Special purpose application software: The software that is
designed to perform a specific task is known as special purpose
application software. This is also called Custom Software. The
software can perform only one task for which it has been designed.
For example, Software to process inventory control, software to
maintain Bank Accounts, software used in Airline Booking System.
Q: Write a note on Disk Operating System (DOS).
What are the types of DOS commands?
Ans:
DOS: DOS is an operating system. It manages the routine work of
computer system, controlling everything from internal memory, monitor
display, keyboard input and external communication. It was developed
by a US company called Microsoft in 1981. It provides us with two types
of commands namely, internal and external commands.
Internal commands: Internal commands are built into DOS, and
loaded with DOS. These commands are immediately available in memory
and con not be seen in the disk files list. The internal commands are
DIR, CLAS, DATE, TIME, COPY, VER, VOL, DEL, TYPE, REN, PROPMT,
MD, RD, CD, and PATH etc.
External Commands: External commands are stored on disk as files.
Some commands are FORMAT, CHKDSK, LABEL, DISKCOPY, PRINT, SYS,
EDIT, XCOPY, DELTREE, and DOSKEY.
Q: What is an operating system?
Ans:
Operating System: An operating system is a set of programs
which starts a computer and allows the users to interact with the
hardware and software present in the computer. Without operating
system, a computer cannot do anything useful. Some of the popular
operating systems used in personal computer are: DOS, Windows, UNIX,
Linux, Solaris, etc.

31

Sir Sadiq’s computer notes for class IX
Chapter no 7. Computer software

Q: What are wildcard characters? Why they are used?
Ans: Wildcard characters: While looking for a particular file (using DIR
command to see the directory or DEL command to delete files or COPY
command to copy files), you can use two special characters called
wildcards. A question mark (?) can take the place of any single character
and an asterisk (*) can replace any group of characters, even the entire
filename or extension. They can be used when searching/deleting/ or
copies files on a disk.
For example:
TEST?

Includes TEST, TEST1, TEST2, TESTS, but
not the TESTS1 (it has an extra character)

*.EXE

It refers to all files with .EXE extension.

*.*

Includes all files on the default drive.

Q: What is a Directory? What DOS commands are used to create,
change and delete a directory?
Ans: Directory: A directory contains information about each file such as its
name, size in bytes and the date and time they were created or last
updated. The main directory, called the root directory, can contain many
sub-directories and these subdirectories can contain other subdirectories.
The root directory is not referred to by name. Instead, it is always
indicated by a backslash (\). If you are working in a subdirectory called
IMAGES, the prompt will be:
D:\IMAGES>
We use:
MD or MKDIR command

To create directory

CD or CHDIR command

To change directory

RD or RMDIR command

To remove directory

32

Sir Sadiq’s computer notes for class IX
Chapter no 7. Computer software

Write full name of the following:
C.P.U

=

Central Processing Unit

C.U

=

Control Unit

M.U

=

Memory Unit

A.L.U

=

Arithmetic Logic Unit

RAM

=

Random Access Memory

ROM

=

Read Only Memory

L.C.D

=

Liquid Crystal Display

C.R.T

=

Cathode Ray Tube

C.D

=

Compact Disk

GUI

=

Graphical User Interface

BCD

=

Binary Coded Decimal

EBCDIC

=

Extended Binary Coded Decimal Interchange Code

ASCII

=

American Standard Code for Information Interchange

DOS

=

Disk Operating System

DIR

=

Directory

BASIC

=

Beginner’s All-purpose Symbolic Instruction Code

COBOL

=

Common Business Oriented language

ATM

=

Automatic Teller Machine

33




Sir Sadiq’s computer notes for class IX
Q:

Chapter no 8. Introduction to windows operating system
What is Windows or windows operating system?

Ans: Windows: Windows is an operating system that helps in operating the computer. It
also manages the hardware and the software present in the computer. We cannot
use the computer without an operating system. Many operating systems are available
but windows is the most popular in personal computers because it is very simple and
easy to learn and use. It helps us to work on the computer. It shows us the
programs, files and folders and allows us to use them. It is a Graphical User Interface
(GUI) based operating system. In DOS we have type-in command, but in windows
command are located on the screen in the form of icons. There are different versions
and flavors of windows, e.g. Windows 2000, Windows XP, Windows NT, Windows
2007, and Windows 8 etc.
Q:

Define what is Desktop? What are its elements?

Ans: Desktop: Windows “Desktop” is like a working surface of a desk. Desktop is where
our applications, folders and shortcuts are located. Desktop contains the following
items:
* Icons
* Task Bar * Start Menu
ICON: An icon is a small colorful graphical picture that
represents an object like a file, folder, program or any
hardware component of the computer. Every icon has a label,
which identifies it. The labels can be changed.
Icons of the Desktop: My Documents, My Computer, My
Network Places, Recycle Bin, Internet Explorer etc.
Task Bar: The Taskbar is a horizontal bar located at the bottom of Windows
Desktop. It contains the Start Button on its left corner and a clock at its right corner.
It between, it displays the buttons for the currently running programs. When we start
a program or a window is opened, a button representing its window appears on the
Taskbar.
When we close the program or window, the button disappears.
Start Button: Start button is present on the left corner of the
Taskbar. It is used to open various links required to use the
computer. On clicking the Start Button, a menu of various items
pops up on the screen. This menu is called the Start Menu. It
shows all the links required to use and maintain the computer.
We can shutdown, restart and / or standby the computer using
the Star button.
Q: Explain the function of windows explorer.
Ans: Windows Explorer: Windows explorer provides another way
to view the contents of the disks and its folders in a tree like
structure. We can navigate between files and folders though
explorer. Files, folders and programs can be opened, moved
and deleted through it. Explorer window has tow panes. Left
pane displays disk drives and folders with + and – sign before
them. Right pane displays the contents of the selected item
from the left pane.
33

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 8. Introduction to windows operating system
Write short notes on the following.
Icon
Taskbar
Recycle Bin
My Computer
My Documents
Windows
Ans: Icon: An icon is a small colorful graphical picture that represents an object like
a file, folder, program or any hardware component of the
computer. Every icon has a label, which identifies it. The labels can
be changed.
Icons of the Desktop: My Documents, My Computer, My
Network Places, Recycle Bin, Internet Explorer etc.
Taskbar: The Taskbar is a horizontal bar located at the bottom of
Windows Desktop. It contains the Start Button on its left corner
and a clock at its right corner. It between, it displays the buttons
for the currently running programs. When we start a program or a window is opened,
a button representing its window appears on the Taskbar.
When we close the program or window, the button disappears.
Recycle Bin: Recycle Bin makes it easy to delete and
undelete
files
and folders. When a file or folder is deleted from any
location,
windows stores it in the Recycle Bin. If a file is deleted
accidentally, we
can move it back from the Recycle Bin. We can also empty recycle bin to save disk
space. We can delete a file or folder by select them and press delete key. We can
also use right mouse button menu to delete files or folders.
My Computer: My computer lets us browse the contents of our computer. The
common tasks that we can perform through my computer are:
1. Access information stored as different storage devices connected with the
computer, such as hard disk, floppy disk, CD / DVD ROM or USB.
2. Create, move, copy, delete or rename files, folders and programs from one
disk to another disk.
3. Execute or run programs from the disks.
4. Configure devices of the computer.
5. Add or remove a printer
My Document: It is a desktop folder that provides a convenient place to store
documents, graphics or other files that we want to access quickly. On the desktop it
is represented by a folder with a sheet of paper in it. When we save a file in a
program such as word pad or paint, the file is by default saved in my documents
unless we choose a different location. OR My Documents is the name of a special
folder on the computer’s hard drive that is commonly used to store a user’s
documents, music, pictures, downloads, and other files.
Windows: It is a rectangular area of Screen that displays different
information. In windows every folder or application has a windows. Following are the
properties of a windows.
1. Every window has a title bar which displays the name of the widow.
2. Windows can be resized,
minimized and maximized by
pressing the buttons at the top
right corner, of the title bar.

3. A window can be closed by pressing the X button at the right of the title
bar.
34

Sir Sadiq’s computer notes for class IX
Q:

Chapter no 8. Introduction to windows operating system
4. A window can be moved at any location of the screen.
How can you change wallpaper of the Desktop?

Ans: Changing
of
Wallpaper:
Wallpaper of the desktop
change by following steps:
1. Close or minimize all
open window
2. Click the right button on
any blank space of the
desktop
3. A menu will appear click
on properties
4. Display property dialog box will appear
5. Click on the background tab
6. Select from the list of currently available wallpapers
7. Click on the “apply” button
8. Click on the “Ok” button
9. Wallpaper has been changed
Q: What is computer Virus?
Ans: Computer Virus: A computer virus is a hidden program, which can infect other
programs by modifying them and causes data loss. It attaches itself to other
programs and executes secretly every time the host program is executed. The virus
replicates itself within a computer system. Some viruses hidden in the computer can
infect the computer at a particular time called Time Bomb viruses. Computer viruses
may perform the following malicious functions.
1. It infects other programs
2. It destroys the data on disk.
3. It spreads from one disk to another.
4. Sometimes it makes the computer unusable.
5. It increases the file size and replicates itself, thus making the wastage of
memory space.
Some names of Viruses: There are a large number of viruses present in the
computer world. These viruses include Brain (developed by a group of Pakistanis),
Joshi, Jerusalem, Friday 13th, Chernobyl, etc.
Q: What is Antivirus?
Ans: Antivirus: Antivirus is another software that when executed removes the virus
programs from the disk. Antivirus software has been developed to get rid of the
computer viruses that can destroy the valuable data and causes the computer to
malfunction. Some of the antivirus programs available are:
* Norton Anti-Virus
* MacAfee * Avast
* PC clean
* AVG
* Panda
Q: How can you create a folder?
Ans: Creating a folder:
1. In My computer or windows explorer, select the drive where you want to
create the new folder.
2. In the File menu, click on the New and then click on Folder
3. The new folder appears with the temporary name.
4. Type a suitable name for the new folder and press the enter key.
35

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

1

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Define the term computer.
Ans: Computer is an electronic device that accepts data
and instruction as input process the data according to
the given instruction and produce information as
output.
Q: Define the terms Hardware and Software.
Ans: Hardware: The physical or tangible components forming a computer
are called hardware. It includes not only the computer but also the
cables, connecters, power supply units and peripheral devices such as
the keyboard, mouse, audio speaker, printer etc.
Software: Software refers to the program that instructs the computer
what to do and how to do. The term software refers to the non-physical
elements of a computer system. Windows, Microsoft Office, Flash,
Photoshop are the example of software.
Q: Define language translator.
Ans: A translator is required to execute any high-level language program.
Each language has a different language translator, while the function of
each translator is to convert high-level program into machine code.
Or
Language translators are the programs that are used to convert source
program to object program.
Q: What are (machine language) low-level language & high-level
language?
Ans: Low-Level Language (Machine Language): Every creation of this
universe has its own language, likewise, computer has language that is
called machine language, for instructing computer to perform specific
task. It is the language of 0s and 1s.
High-Level Language: High level languages are closer to human
language than low-level language and include statement like GOTO and
PRINT which are regular words.
Q: Why the source code is needed to be translated into machine
code?
Computer program written in a high-level language which is converted
into object code or machine code by a compiler is called source code.
Source code is the only stage where a programmer can read or modify a
2

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

computer program. It is needed to be translated into machine code to
execute it. Because computer only understand machine language.
Q: What is assembly language?
Ans: Assembly Language: Assembly language is the next level of
programming language. Each computer has its own unique assembly
language. In assembly language, the statements are written in symbolic
codes. Assembly language is very close to machine language that is why
it is called a low-level language.
Q: What are assemblers?
Ans: Assemblers: The assemblers are language translator for low-level
symbolic language used in assembly language. Assemblers can translate
Source Program into Object Program. An assembler translates one
source instruction program into exact one machine code. Each low-level
symbolic language has its own assembler.
Q: Define interpreter.
Ans: Interpreter: An interpreter normally means a computer program that
executes, i.e. Programs, instructions’ written in a programming language.
Most interpreting systems also perform some translation work, just like
compilers. An interpreter may be a program that either executes the
source code directly.
Q: Define compiler.
Ans: Compiler: Compiler is similar to assembler in a way that it translates
the high-level language program into machine language. It is used to
translate entire program at once. The original program is called Source
program while translated program is called Object program. Each
high-level language has its own compiler.
Q: What are the types of computer? Or Define the types of
computer according to data handle.
Ans: Computer can be classified into three types. This classification is based
on the hardware structure & the way through which physical quantities
are represented in a computer. The three types are:
1. Analog computer
2. Digital computer
3. Hybrid Computer
3

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Analog computer: The term analog is taken from the
word analogous which means similar. Analog computers
are commonly used for scientific and engineering
problems, particularly in chemical industries, electric
power plant & petroleum refineries.
Digital Computer: Digital computers are computers
that specialize in counting. Unlike the analog computer
which receives data in a continuous form, the digital
computer handles values that are in binary O or 1. All
commonly used computers are digital.
Hybrid computer: Hybrid computer is combination of
analog and digital computer system. These are the
machines that incorporate in a single computer both
analog & digital features. A hybrid computer uses analog
to digital conversion & digital to analog conversion, and
may input or output either analog or digital data. These
computers are used such as space vehicle simulations
and training of astronauts.
Q: What do you know about ABACUS? & where is used now a day?
Ans: ABACUS: The Abacus, which was invented about 5000 years ago. The
Abacus was developed and used in China. This is the simplest manual
device which consist of a rectangular frame with vertical wires containing
are number of beads for representing units, tens, hundreds, thousands
and so on calculation were done by moving the beads along with the
wires. Early merchants used the Abacus to keep trading transactions. But
as the use of paper and pencil spread, the ABACUS lost its importance. It
looks nearly 12 countries, however, for the next significant advance in
computing devices to emerge.
Q: What are the impacts of computer and the internet on society?
Ans: society: Today computers are constantly becoming a part of everyday
life and have significantly influenced our life style. Computers are used in
everything from the home PC or Laptop to appliances such as
microwaves oven, washing machines, entertainment devices, mobile
phones and even in our cars. Not only have computers had a great
impact on our family, life but also on education and the work place.
Education: The use of computer for education purpose has been highly
beneficial for the students and teachers. As well news, assignment, tests,
lectures, notes etc can be on the internet for students to access both at
school & from home. Children now learn online through websites and
4

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

videos and audio conferencing. Computers are also very beneficial for
research purpose.
Work Places Business: Computer technology has advanced greatly in
the past couple of years and in May large business, computers have
begun taking the place of human. It is more that they are helping us to
do our work. Stores use computer to keep track of their files & many
stores have also started using cash registers. All business keep records
on computer & many of them depend entirely on their computer system.
Today Social media web site are also introduced their business. Mostly
work is done online through compute.
Q: What are the advantages of 2nd and 4th generation?
Ans:
1.
2.
3.
4.
5.
6.

Second Generation:
Smaller in size as compared to first generation
Much reliable
Computations were performed in microseconds
Less hardware failures
Better portability
Commercially used

Fourth Generation:
1.
2.
3.
4.
5.
6.
7.
8.
9.

Smallest in size
Very reliable
Heat generated was negligible
No air conditioning was required in many cases
Minimal maintenance was required
Hardware failure was negligible
Very easy moveable
Totally general purpose
Very inexpensive

5

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Describe the types of computer according to capacity.
Ans: Super Computer: These are the largest and fastest machine. Today
where numerical computations are carried out at speeds of up to 50
million operations per second. Super computers are very sophisticated
machines designed to perform complex calculations at fastest speed.
Super computers are used to model very large dynamic systems, such as
weather patterns, national or global weather forecasting, satellite
tracking, cold-testing of atomic & nuclear weapon etc. Cray research &
Intel are well-known producers of super computer.

Mainframe Computer: A mainframe
originally meant the cabinet containing
the central processor unit of a very
large computer. After minicomputer
became available, the word mainframe
came to refer the large computer itself.
Large scale computer are very
expensive machines and their main
concern is to prove their cost
effectiveness. These computers are
valuable to the larger firms, which can
provide concurrent & continuous
applications, involving thousands of
employs and hundreds of thousands of
6

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

customers accounts on a daily basis, for example, bank to keep track of
millions of checks and deposits, airlines to schedule thousands of flights
and make seat reservation & governments to keep track of their citizens
etc.
Minicomputer: Minicomputers are increasingly
powerful & do almost anything that large
computers do, only more slowly & at much lower
cost than mainframes. These computers are
smaller
than
mainframe
&
larger
than
microcomputers in size.
A minicomputer is a multi-processor system
having terminals attached to it and it is capable of
supporting 4 to 200 users simultaneously.
Micro-computer: Microcomputers are computers that are powered by
micro-processors. Sometimes they are referred as single-chip
processor or a system on a chip. Micro-computers or personal
computers are the smallest computers, designed to be used by
individuals for writing, illustrating, budgeting, playing games &
communicating with other computers.

7

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Define different state between hardware & software.
Hardware

Software

The
physical
components of Software is the set of instructions
computer & other attached input stored as program that makes the
output devices are called hardware. hardware run.
All hardware components may be They are designed by the
connected mechanically, electrically manufacture or the programs to
or electronically with each other.
fulfill the requirement.
Software are of two types:
Hardware includes input devices, System software (DOS,
output devices, central processing Windows, Unix, Linux etc.)
unit, Backing storage, electronic Application software (Microsoft
circuit.
Office, Photoshop, Flash, Inpage,
Corel Draw etc)
Q: What are the capabilities and limitation of computer?
Ans: The Capabilities: The capabilities of computer are: Speed, repetitions,
accuracy, logical operations, store and recall information, self-checking
and self-operating. While its limitations are that it cannot generate
information on its own, it cannot correct wrong instructions. It cannot
come up with an original decision.
Q: What is the difference between analog and digital computer?
Analog

Digital

Represent data continuously.

Represent data discretely as 0s
and 1s.
Signal types-continuously varying Single types-sequence of voltage
electromagnetic wave.
pulses over time.
Transmission-means of transmission Transmission-concerned
with
of analog signal without regret to content of signal.
their content.
Applications-measurement
of Application-business, science and
different
physical
quantities home.
scientific applications.

8

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Describe the classification according to capacity.

Super
Computer

Mainframe
computer

Minicomputer

Microcomputer

Processing
Power

Extremely high

Very high

High

Moderate
low

Size

Very large

Moderately
Large

Medium

Scientific
Business,
& academic
Applications research
development
learning

Business,
academic
learning

Use

Simulations of
Centralized
highly complex
computing.
system

Centralized
Computing

User

Federal
agencies
research
organization

Business
university

& Business
university

to

Small
to
handy
Business,
scientific,
research
&
development
academic
learning
General
to
specialize for
variety
of
used
&
needs.
Professional
in business,
Scientific
&
academic
fields

Q: Write a short story of the history and development of
computers?
Ans: History of computers: Today computers do much more than simply
computer numbers. Name of early computing machine are ABACUS
(3000 B.C), Napier’s bones (1612 A.D), Slide Rule (1622 A.D),
Pascaline (1642 A.D), Babbage’s difference engine (1822 A.D),
Babbage’s Analytical engine (1832 A.D) and Hollerith’s Tabulating
Machine. These innovations were developed in a period termed as Dark
age and Middle age of the computer. After Dark and Middle Ages, the
computer technology and ideology improved and the period was termed
as Modern age of computer. The computers in Modern age are
categorized in five generations: 1st generation (Vacuum Tube), 2nd
generation (Transistor), 3rd generation (I.C), 4th generation
(microprocessor), 5th generation (artificial intelligence).

9

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Describe the five generation with the help of generation table.
Period
Specialties

First
Generation

Second
Generation

Third
Generation

Fourth
Generation

Fifth
Generation

1940-1956

1956-1963

1964-1971

1971-1981

1981-

Internal
Vacuum
Computer
Tube
Components

Transistor
s

Integrated
circuit IC
large scale
integration

Very large Microscale
processor
Integratio
n VLSI +
microprocessor

Size of the Very
computer
Huge

Smaller
the first
generation
, mini
computer

Much
Very small Ting
smaller
Laptop
computer
than
diary
second
generation
, micro
computer

Speed of the Low
computer
speed
compute
r

10 times
faster than
first
generation

100 times
faster than
second
generation

10 times
faster
than third
generatio
n

Much
faster
than
fourth
generatio
n

Magnetic
disk

Disk
storage,
floppy
disk

Floppy
disk, disk
storage,
CD-ROM

Storage
devices

Punch
Magnetic
card and tapes
magnetic
tapes

Main
memory

Magnetic ROM, RAM PROM,
drum
DRAM

EPROM,
SPRAM

EPROM,
SIMM

Programmin
g language

Machine Assembly
language language

Much
easier
high-level
language

Artificial
language

Quantity
Used

Hundred
s

Million

Billion

High level
language

Ten
Thousands Thousand
10

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Define Napier’s bones.

Ans:
Napier’s Bone: In 1612, John Napier
made the first printed use of the decimal point
(after it had been invented in the Netherlands),
and invented logarithms and several machines
for multiplication. Best known of his machines
was the “bones” or “Napier’s bones”. This
device consisted of a set of eleven bones or
rods with numbers marked on them.
Q: Define Babbage’s difference engine.
Ans:

Babbage’s difference engine: In 1812, Babbage noticed a
natural
harmony
between
machines
and
mathematics.
Babbage’s first attempt at solving
this problem was in 1822 when
he proposed a machine to
perform differential equations,
called difference engine. Powered
by steam and large as a
locomotive, the machine would
have a stored program and could perform
calculations and print the results automatically. Its goal was to output
data as printed tables, a necessity for a number of financial, military,
government, and engineering endeavors.

Q: Define Babbage’s Analytical engine.
Ans: Babbage’s analytical engine: Ten years
later (after creation of difference engine)
Babbage proposed a more general-purpose
computer and called it an Analytical engine.
The Analytical Engine would use steam for
power, have storage capacity (memory of
1,000 numbers of up to 50 decimal digits
long), and the ability to process instructions in
any sequence. For input, the
computer
would use punched cards to enter the machine’s
instructions.

11

Sir Sadiq’s computer notes for class IX
Chapter no 1. Introduction to computer

Q: Write Artificial Intelligence. Or fifth generation.
Ans: Fifth Generation: Fifth generation computing devices, based on
artificial intelligence, are still in development, though there are some
applications, such as voice recognition, that are being used today. The
use of parallel processing and superconductors is helping to make
artificial intelligence a reality. Quantum computation and molecular and
nanotechnology will radically change the face of computers in years to
come. The goal of fifth- generation computing is to develop devices that
respond to natural language input and are capable of learning and selforganization.
Q: What is Artificial Intelligence. Or fifth generation
Artificial intelligence (AI) is an area of computer science that
emphasizes the creation of intelligent machines that work and react like
humans. Some of the activities computers with artificial intelligence
are designed for include:
 Speech recognition
 Learning
 Planning
 Problem Solving

Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq, smsadiqnoori@gmail.com

12

Sir Sadiq’s computer notes for class IX
Chapter no 2. Computer Components

1

Sir Sadiq’s computer notes for class IX
Chapter no 2. Computer Components

Q: How does a computer work?
Ans:
A general purpose computer has for main sections. (i) The arithmetic
and logic unit (A.L.U), (ii) The control unit (C.U), (iii) the memory unit
(M.U) and (iv) the input and output devices (I/O). These ports are
interconnected by busses often made of groups of wires.
The control unit (C.U) registers and basic (I/O) are collectively
known as a central processing unit (C.P.U). CPUs have typically been
connected on a single integrated circuit called a microprocessor.
Q: Define ports and describe its types.
Ans:
Port: A port is a socket at the back of a computer used to plug in
various devices. Personal computers have various types of ports internally,
there are several ports internally, and there are several ports for
connecting disk drives, display controllers and keyboard. Externally,
personal computers have ports for connecting modem, printers, scanners
and other peripheral devices. These are two types of ports normally:
1. Serial ports
2. Parallel ports
Serial port: A port or interface that can be used
for serial communications, in which only 1 bit is
transmitted at a time, is called serial port. A serial
port also called a male connector which has 9 or
25 pins.
A serial port is a general-purpose interface that can be used for
almost any type of device, including modems, mice & printers.
Parallel port: A socket on a computer for
transmitted data in parallel, which means more
than one bit at a time, is called parallel port.
These are may be 8, 16 or 32 channels (wire);
each channel carries one bit of information, so eight
channels would be used to transmit 8-bits at a time.
A parallel port is also a female connector, which has 25 holes, and
the cable that plugs into it has 25 pins. It is the kind of port used to connect
tape devices, CD-ROMs, extra hard disks and most of the printers.
Q: Write about data processing cycle.
Ans:
Data processing cycle: Data processing cycle is the way to
accomplish a work by computer. It has three basic steps, input, process
and output. In the input step we can use many input devices to enter data
in computer. During processing step the inputted data is processed in
2

Sir Sadiq’s computer notes for class IX
Chapter no 2. Computer Components

central processing unit CPU. The results of processing steps are collected
in output step.
Q: Define motherboard?
Ans:
Motherboard: It is a rectangular cord
containing the circuitry that connects the processor
to the other hardware. In most personal computers
many internal devices such as video card, sound card
and other devices are housed on this board.
Q: Define Register.
Ans:
Register: A register is a type of volatile or temporarily memory and
it sit a part of a CPU. Data currently being processed is stored in
registers. There are fourteen basic registers shared by ALU and CU.
Q: What is multitasking?
Ans:
Multitasking: If several programs are running at the same time,
then the interrupt generator might be causing several hundred
interrupts per second, causing a program to switch each time. Since
modern computers are typically executing, instructions several orders of
magnitude faster than human perception. It may appear that many
programs are running at the same time even though only one is very
executing in any given instant. This method of multitasking is sometimes
termed time sharing since each program is allocated a slice of time in
turn.
Q: Differentiate between RAM & ROM.
RAM
RAM stands for Random Access
Memory.
It is a volatile memory.
It is erasable and alternated
memory.
It is not a preprogrammed chip.

ROM
ROM stands for Read Only
Memory.
It is not a volatile memory.
It is increasable and unsaturated
memory.
It is a pre-Program chip.

It is also referred as read and The programs stored in ROM are
writes memory.
referred as firmware.

3

Sir Sadiq’s computer notes for class IX
Chapter no 2. Computer Components

Q: What is difference between internal memory & external
memory?
Internal Memory
It is a set of chips located on the
memory data is stored temporary
during processing.
It is a volatile memory.
Internal memory is very fast for
accessing data.
Mostly they are semiconductor in
nature.
Register, Cache, RAM etc are
example of internal memory.

External Memory
The physical unit or material on
which external memory or
secondary memory.
It is not a volatile memory.
External memory is slow accessing
dat.
Mostly they are magnetic / optical
/ semiconductor in nature.
Hard disk, floppy disk, magnetic
type etc are example of external
memory.
Q: What are input and output devices?
Ans:
Input Devices: Input Devices are physical equipment that read or
translate data consisting of alphabets, numbers or other symbols into
electronic impulses, which can be understood by the computer. The
devices which we use to put data into the computer are called input
devices. Keyboard, Mouse, Scanner, Microphone, Joystick, Light pen is
the example of the input devices.
Output Devices: The output devices are also physical equipment,
which present the outcome of the computations and related activities
carried out in the CPU so that these can be understood by Humans. The
devices which we use to get data from the computer are called input
devices. Monitor/LCD, Printer, Plotter and speaker are the example of
the Output devices.
Q: Define the term Bus in general. What are the purposes of data
bus, address bus and control bus?
Ans:
Buses: A processor communicates with Input/output circuits and
memory by using signals. These signals travel along a set of wires or
connections called bus that connects the different components together.
Or Bus is a set of wires that is used as a communication path.
There are three kinds of buses: Address bus, control bus and data
bus. The address bus carries address signals; control bus carries control
signals while data bus carries data signals.
Address Bus: Connections between the CPU and memory which
transmit the address from which the CPU will read, or to which the CPU
4

Sir Sadiq’s computer notes for class IX
Chapter no 2. Computer Components

will writ, Or, A collection of wires connecting the CPU with main memory
that is used to identify Address in main memory is called Address Bus.
Control Bus: The control bus carries signals that report the status of
various devices. It carries control information between the CPU and
other devices.
Data Bus: It is communication route through which data can travel
between the computer’s central processing unit, memory and
peripherals. The speed at which data can travel between hardware
components depends on the number of wires in the bus. Each wire
transmits a single bit at a time, so 8 bits bus can transfer 8 bits at a
time. Similarly, 16 bits bus can transmit 16 bits and so on.
Q: Define the following terms with their major functions:
a. Arithmetic and logic unit (ALU)
b. Control unit (CU)
Ans:
Arithmetic and logic unit: This is where arithmetic operations
such as addition, subtraction, division and multiplication are performed.
This is where logical operations are also done such as comparison
between two pieces of data. The ALU performs arithmetic and logical
operations.
Control unit: All the computer’s resources are managed by the control
unit (CU). It works like a traffic cop directing the flow of data between
the components of the CPU and to and from the other devices. It
extracts instruction from memory (RAM) and decodes and executed
them, calling on the ALU when necessary. It also controls input and
output devices and data transfer process.
Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq, smsadiqnoori@gmail.com

5




Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

12

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

Q: What are Input Devices?
Ans:
Input Devices: Input devices are physical
equipment that read or translate data consisting of
alphabets, numbers or other symbols into electronic
impulses, which can be understood by the computer. The
purpose of input devices is to pass information into the
memory unit of the CPU and convert the characters into
binary patterns.
There are different types of Input Devices used to transfer data in
the computer. E.g. Keyboard, Mouse, Trackball, Joystick, Scanner etc.
Q: What are the parts (division) of Keyboard? Or Write a note on
Keyboard.
Ans:
Keyboard: A keyboard is a primary input device used to feed
information and algorithm directly into a computer. It consists of a set of
keys, which uses the same key arrangement as the mechanical and
electronic typewriter keyboards. The standard arrangement of alphabetic
keys is known as QWERTY keyboard. A standard keyboard includes about
100 or 104 keys and each key sends a different signal to the CPU. These
keys are divided into five different groups. These
groups are:
1. The alphabet keys (Aa to Zz)
2. Numeric Keys
(0 to 9)
3. Function Keys
(F1 to F12)
4. Screen navigation and editing keys (Cursor keys, Home, End, Page
up and Page down keys)
5. Special function keys
(Enter, Caps Lock, Shift etc)
Q: What are standard alphanumeric keys?
Ans:
Alphanumeric keys: An alphanumeric
keypad is a main part of a keyboard that contains
both numbers and letters. By using this keypad
the letters (a-z, A-Z), the numbers (0 – 9),
symbols (!@#$%^&*()_+-=[]{},~etc) may be typed. Many of these
characters are typed by holding shift key. Any type of data can be entered
through this keypad.

13

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

Q: What is numeric keypad?
Ans: Numeric Keypad: The Numeric keypad is located on the
right Side of keyboard. When “Num lock” key is pressed then
the numbers on numeric keypad can be used. These keys
are used to input numeric data only. It looks like a simple
calculator which includes number keys from 0 to 9 digits.
Q: What are function keys?

Ans: Function Keys: These are twelve keys marked as F1 to F12 located at
the top of the keyboard. All of these keys have pre-defined meanings
which provided to a programmer to attach special functions to each key
depend on the application software. These keys are used to input
commands without typing the long commands. These keys perform
different functions in different programs. Fr example F1 key is a help key
in most of the program.
Q: What is screen navigation and editing keys?
Ans:
Screen Navigation keys: These keys are provided to move cursor
around in the screen. Most keyboards include the following cursor
movement keys: Arrow keys (left, right, up, down), Home and end keys
(to moves the cursor to the beginning of the line and to the end of line),
Page up and page down keys (to make the cursor jump page by page).
Q: What is the use of enter key?
Ans:
Enter key: Enter key tells the computer that an
instruction is completed or to transfer a written instruction or
data into the ALU. Enter key is also used to move the cursor
to the next line by adding one-line space when we want to
start a new paragraph.

14

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

Q: Write about Mouse.
Ans:
Mouse: The mouse is an alternate input device
normally called a “pointing device”. It is used to
move a pointer on the computer screen in order
to point to a place on a display screen and to
select one or more actions to be taken from that
position. The mouse is an integral part of the
Graphical
User Interface (GUI) of any personal computer. The mouse apparently got
its name by being about the same size and shape as a toy mouse.
A mouse has two or three buttons in the front. The left button is
used most frequently. We use mouse for selecting, clicking, dragging and
dropping.
Q: Write about Track ball?
Ans:
Track Ball: A track ball is an input device. The
function of a track ball is same as mouse. We use a
trackball by rolling the ball with our palm or fingers
in the direction we want the pointer to go. The user
spins the ball with fingers to move the pointer on the
screen. The advantage of trackballs over mouse is
that the trackball is stationary so it does not require
much space to use it.
Q: Write about Joystick.
Ans:
Joystick: A Joystick is a hand-held stick like the
joystick in an aero plane, which is used as a pointing
device. Joysticks are used mostly for computer or video
games, but they are also used occasionally for CAD/CAM
systems and other applications. The joystick is just like
a vertical handle that is gripped by hands. This handle is
used to move an object on screen in any direction.
Q: Write about light pen.
Ans:
Light pen: Light pen is a pointing input device that
contains a photo detector or light source, and that allows
interaction with a computer through a specially designed
monitor / display screen. It is usually used for engineering
designing. A light pen is similar to a mouse, except that
with a light pen we can move the pointer and select
objects on the display screen by directly pointing to the objects with the
pen.
15

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

Q: Write about digital camera.
Ans:
Digital camera: A digital camera is another
hand-held, portable input device that takes
pictures as input. Normal cameras capture picture
on a special coated film, while digital camera
capture imaged electronically without the need of
a film. The digital camera stores then snapshots in
its memory then user can copy them into a
computer. These images can be edited, printed or
copied in a document etc. Most digital cameras
have abilities to increase their capacity by
accepting additional memory.
Q: Write about scanner.
Ans:
Scanner: Scanner is an input device that reads images or text and
converts the data into digital signals, which can be directly fed and stored
in computer. Graphical scanners read photos or other images into the
computer and digitize them, producing bitmapped graphics files. The
scanner saves an image of the graphic as a file on the computer. Scanner
usually comes with software such as Adobe Photoshop product. Some
most common types of scanners are follows:
1. Hand-held scanners
2. Flatbed scanners
3. Sheet-fed scanners
Q: What is output? Or what are output devices?
Ans:
Output Devices: The data processed according to instructions is
called meaningful information. Meaningful information is the result of work
done by the CPU. It is either shown on the screen or printed on a sheet of
paper. This result is known as output. The output can be shown on output
devices. The output devices convert computer signals into a form to be
understood by human or devices. Some of the output devices are monitor,
printer, plotters, output on microfilm etc.
Q: Write a note on Monitor.
Ans:
Monitor: It is also called a display screen. The monitor usually refers
to the entire box. It is a device that displays text and graphics generated
by a computer. In the future flat-screen LCD (Liquid Crystal Display) panels
are likely to completely replace today’s bulky cathode ray tube (CRT). The
basic two types of monitors are:
16

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

1. CRT monitors, which is similar to the television
screen and also works in the same way. It uses a
large vacuum tube called Cathode Ray Tube (CRT).
2. Flat-Panel Display (Liquid Crystal Display or LCD),
which is usually used with portable computers but
now have become very popular with the desktop
computers too.
In terms of color capabilities, all the monitors fall into three classes:
1. Monochrome: Monochrome monitors actually display two colors,
one for the background and one for the foreground. The color can
be black and white, green and black, or amber and black.
2. Gray-Scale: A gray-scale monitor is a special type of monochrome
monitor capable of displaying different shades of gray.
3. Color: color monitors can display anywhere from 16 to over 1
million different colors. Colors are sometimes called RGB (Red,
Green and Blue) monitors.
Q: What is printer? Write about it.
Ans:
Printer: Printer is a device that accepts text and
graphic output from a computer and transfers the
information to paper, usually to standard size sheets of
paper. There are many different types of printers. In terms
of the technology utilized, printers fall into basic two
categories: a) Impact printers b) Non-impact Printers.
a) Impact printers: Impact printers include all printers
that work by striking an ink ribbon. Daisy wheel, dot
matrix, and line printers are impact printers. Impact
printers are much noisier than other printers.
b) Non-Impact printers: Non-Impact printers include laser printers,
ink-jet printers etc. They are quiet and speedy printers. Non-Impact
printers form characters and images without making physical contact
between printing mechanism and papers.
Q: Write a note on Plotter.
Ans:

Plotter: A plotter is an output device for printing
high quality drawings. It helps us in getting graphical or
pictorial representation of information. Plotter is used
17

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

where fine work is involved like drawing graphs that requires a great deal
of accuracy. It is generally used by architects and engineers. It is usually
used for drawings or taking large posters. Plotters can be of two types:
Pen plotters and Electrostatic plotters. Pen plotters have an ink pen
attached to draw the images, and electrostatic plotters work similarly to a
laser printer. Pen plotters are further divided into two types: Drum plotters
and Flatbed plotter.
Q: Write a short note on Drum plotters and Flatbed plotters. OR
Types of a plotter.
Ans: Drum plotters: A drum plotter consists of a solid
cylindrical drum that has embossed characters in bands
on its upper surface. This drum rotates at a high speed.
The speed of drum plotter is form 300 lines per minute
to 2000 lines per minute. In drum plotters, the pen is
moved in a single axis track and the paper itself moves
on a cylindrical drum to add the other axis or dimension.
Flatbed plotters: It is a plotter in which the paper is
fixed on a flat surface and pens are moved to draw the
image. This plotter can use several different color pens to
draw with. The size of the plot is limited only by the size
of the plotter’s bed.
Q: What is soft copy and what is hard copy? Or Write the difference
between softcopy and Hardcopy?
Ans: Softcopy: Screen output is known as softcopy because it is intangible
and temporary. Or The output displayed on the monitor is called soft copy.
We cannot touch it. It is editable.
Hardcopy: Paper output is known as hardcopy because it is tangible and
can be permanent. Or The output displayed on the paper is called hard
copy. We can touch it. It is a non-editable.
Q: Which device is used as an input device as well as output
device? Or write about dual devices.
Ans: Dual Devices: Dual devices are devices that are input and output devices
at the same time e.g. disk drive and CD writer. Disk drive is a peripheral
device that read or writes that disks. Similarly, CD writer can write on
compact disk. When these devices are used to read some data from it,
they fall in the category of input devices, while during writing data onto
the disk they will be considered as output devices.
18

Sir Sadiq’s computer notes for class IX
Chapter no 3. Input/Output Devices

Differences

Soft copy and Hard copy
Soft Copy
The output produced by the
computer on display screen or is
in audio or voice form is called
soft copy.
Soft copy is intangible. (It
cannot be touched copy)
It is temporary copy.
It is an editable copy.
Monitor and speaker are
commonly used soft copy
producing device.

Hard Copy
The output produced by the
computer on paper or other
material like transparency etc is
known as hard copy.
Hard copy is tangible. (It can be
touched copy)
It is permanent copy.
It is non-editable copy.
Printers and plotters are
commonly used hard copy
producing devices.

Impact printer and Non-impact printer
Impact printer
An
impact
printer
forms
characters or imaged by striking
a mechanism such as print
hammer or wheel on a linked
ribbon against the paper.
They are noisy printers.
Images or documents produce by
the impact printer is not of good
quality.
They are not very speedy.
Dot-matrix, daisy wheel, drum
printer are the examples of
impact printer.

Non-impact printer
The non-impact printers form
characters and images without
making physical contact between
printing mechanism and paper.
They are quiet printers.
Images or documents produce by
the non-impact printer is of good
quality.
They are speedy.
Thermal, inkjet, laser printers
are the example of non-impact
printer.

Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq smsadiqnoori@gmail.com
19





Sir Sadiq’s computer notes for class IX
Chapter no 4. Storage Devices

17

Sir Sadiq’s computer notes for class IX
Chapter no 4. Storage Devices

Q: Define Computer memory or storage.
Ans:
Memory: Memory refers to the place where data is kept for later
use. For example, a human being has a memory where he/she stores the
things that can be recalled whenever required. In the same way,
computer storage or memory refers to the media and methods used
to keep information available for later use.

Q: What is primary (Main memory) and secondary memory?
Ans:
Primary memory: Primary memory comes in the form of chips
located on the motherboard so that data can travel quickly between
memory and CPU. There are two basic types of primary memory:
1. RAM
2. ROM

(Random Access Memory)
(Read Only Memory)

Secondary memory: Secondary storage is called Auxiliary storage /
external memory that is used to store large quantities of data for longer
period of time and that is not currently being processed. This is the stuff
“filed away”, but ready to be pulled out when needed. It is nonvolatile
(power off does not erase data). It includes Floppy disk, Hard disk, CD
ROM and magnetic tape.
Q: Write a note on RAM.
Ans:
RAM: RAM stands for Random Access Memory. It is a type of
computer memory that can be accessed randomly. The term RAM also
refers to Read and Write memory. Old data and programs can be wiped
out from the RAM chips and new ones can be written on the same. It is
volatile which means that it requires a steady flow of electrically to
maintain the contents. As soon as the power is turned off, whatever data
was there in RAM is lost. It is also called temporary memory. There are
two basic types of RAM.
 Dynamic RAM (DRAM)
 Static RAM (SRAM)
Q: What is the Difference between dynamic and static RAM?
Ans:
DRAM: DRAM (Dynamic RAM) is the most common type. Dynamic
RAM needs to be refreshed thousands of times per second. It uses
capacitors and transistors storing electrical charges to represent memory
18

Sir Sadiq’s computer notes for class IX
Chapter no 4. Storage Devices

states. DRAM chips are small, simple, cheap, easy to make and four time
as much information as a static RAM (SRAM) chip of similar complexity.
SRAM: SRAM (Static RAM) storage is based on the logic circuit known as
flip-flop, which retains the information stored in it as long as there is
enough power to run the device. A static RAM chip can store only about
one-fourth as much data as a dynamic RAM. Static RAM does not need
to be refreshed, which makes it faster than DRAM. It is also more
expensive.

Q: Define ROM and its types.
Ans:
ROM: It is a kind of primary memory. ROM (Read Only
Memory) is a permanent memory. At the time of making a
computer, some programs are stored in ROM. Whenever the
computer is switched on these programs are automatically
executed. These programs are never removed even when the
computer is switched off. It has special programs called Firmware for this
purpose stored in it. The user can read the programs or information from
this memory but cannot write his own program on it. That is why it is
called Read Only Memory (ROM). ROM can be of three types, which are
as follows:
 PROM (Programmable Read Only Memory)
User can
store a program but once the PROM has been used, user cannot
clean it and use it to store something else. It is non-volatile.
 EPROM (Erasable Programmable Read Only Memory) It
provides user both programming and re-programming facilities.
 EEPROM (Electrically Erasable Programmable Read Only
Memory)
It is a permanent memory on which user can write
and erase his programs. Like EPROM, after erasing data user can
reuse it.
Q: What is the difference between SIMM and DIMM?
Ans:
SIMM: SIMM (single in-line memory module) is a module containing
one or several Random Access Memory (RAM) chips on a small circuit
board with pins that connect to the computer motherboard. SIMMs
typically comes with a 32-data bit path to the computer that requires a
72-pin connecter. SIMMs usually comes in memory chip multiples of four
megabytes. The memory chips on a SIMM are typically DRAM chips.

19

Sir Sadiq’s computer notes for class IX
Chapter no 4. Storage Devices

DIMM: A DIMM (dual in-line memory module) is a double SIMM. Like a
SIMM, it’s a module containing one or several random access memory
(RAM) chips on a small circuit board with pins that connect it to the
computer motherboard. A DIMM has a 168-pin connector and support
64-bit data transfer. It is considered that future computers will
standardize on the DIMM.
Q: What do mean by Units of memory and what are the Units of
memory?
Ans:
Units of Memory: Data currently being processed is stored in
memory register. Computer memory is an array of storage boxes, each of
which is one byte in length. Each byte is the combination of eight (8) small
units called bits (binary digit). Each bit is capable to store either 0 or 1
which are used to understand machine language. The smallest unit of
memory is bit, but the smallest accessible unit of memory is Byte because
we can store a single character of information in a byte not in a bit. A
group of four bits is called a nibble but memory of computer is expressed
in bytes.
Prefix
Kilo
Mega
Giga
Tera

Symbol
K
M
G
T

Power of
10
103
106
109
1012

Power
of 2
210
220
230
240

Equivalent
1024
1024
1024
1024

Bytes
K-Bytes
M-Bytes
G-Bytes

Q: Define the following.
1. Floppy Diskette

2. Hard Disk

3. Compact Disk

Ans:
Floppy Diskette: It is a small removable, portable
storage device. It is readable by a computer with a floppy disk
drive. It was a very common and popular storage device. We
carried out data in a floppy and used it in any computer having
a floppy drive to view. The read/write head in the Floppy
Drive reads and writes the data on the floppy. These days floppies come
in a standard size of 3.5 inches. The Floppy Disks we commonly used can
store 1.44 MB (megabytes) of data.
Hard Disk: The main device that the computer uses in order
to store more information is the Hard disk or Hard Drive. It
has a very large storage capacity. We can read as well as
write data on the Hard Disk as many times as we may need.
20

Sir Sadiq’s computer notes for class IX
Chapter no 4. Storage Devices

A hard disk is a magnetic disk on which we can store computer data.
The term hard is used to distinguish it from a soft, or floppy disk. Hard
disks hold more data and are faster than floppy disks. Today’s computers
typically come with a hard disk that contains several billion bytes
(gigabytes) of storage. The storage capacity of a Hard disk is always
measured in megabyte and gigabytes. One gigabyte contains 1024 MB
(megabytes). Nowadays, a normal Hard Disk Drive contains 40 GB
(gigabytes) of disk space.
Compact Disk: A compact disk commonly known as
CD. It is also a portable storage device. It is a circular
disk made of a hare plastic material and is coated with a
very thin layer of metal. It is designed to store computer
data in the form of text and graphics as well as hi-fi
sound. It is popular for distribution of large databases, software and
especially multimedia applications.
Q: Write about magnetic tape.
Ans:
Magnetic Tape: A magnetic tape is also
a storage device from which we can access data
serially like an audio cassette from which we can
hear the songs in order in which they are stored.
When we want to access some particular data from the tap, the device has
to scan through all the data we do not need but that data is stored before
the required one. The best use of the magnetic tape is for the data that
we do not use very often. The recording medium is a plastic tape coated
with some magnetic material on one side only and this coated side is used
to record data. Two kinds of blank spots, called gaps, are set on the tap.
 Interblock gap, which separates logical blocks.
 Interrecord gap, which is wider and separates records.

Sir Sadiq’s Computer Notes for Class IX.
Composed by: Sir Sadiq smsadiqnoori@gmail.com

21