Basic Concepts of Computer :: 1
1
BASIC CONCEPTS OF COMPUTER
1.1 INTRODUCTION
A computer is a programmable machine designed to perform
arithmetic and logical operations automatically and
sequentially on the input given by the user and gives the
desired output after processing. Computer components are
divided into two major categories namely hardware and
software. Hardware is the machine itself and its connected
devices such as monitor, keyboard, mouse etc. Software are
the set of programs that make use of hardware for performing
various functions.
1.2 OBJECTIVES
After going through this lesson you would be able to:
familiarise yourself with characteristics of computers
identify the basic components of a computer
explain the importance of various units of a computer
differentiate between system software and application
software
explain the importance of operating system
get acquainted with open source
appreciate the need of computer security
1.3 CHARACTERISTICS OF COMPUTERS
The characteristics of computers that have made them so
powerful and universally useful are speed, accuracy,
diligence, versatility and storage capacity. Let us discuss them
briefly.
,2 :: Computer and Office Applications
Speed
Computers work at an incredible speed. A powerful computer
is capable of performing about 3-4 million simple instructions
per second.
Accuracy
In addition to being fast, computers are also accurate. Errors
that may occur can almost always be attributed to human
error (inaccurate data, poorly designed system or faulty
instructions/programs written by the programmer)
Diligence
Unlike human beings, computers are highly consistent. They
do not suffer from human traits of boredom and tiredness
resulting in lack of concentration. Computers, therefore, are
better than human beings in performing voluminous and
repetitive jobs.
Versatility
Computers are versatile machines and are capable of
performing any task as long as it can be broken down into a
series of logical steps. The presence of computers can be
seen in almost every sphere – Railway/Air reservation, Banks,
Hotels, Weather forecasting and many more.
Storage Capacity
Today’s computers can store large volumes of data. A piece
of information once recorded (or stored) in the computer,
can never be forgotten and can be retrieved almost
instantaneously.
1.4 COMPUTER ORGANIZATION
Fig.1.1: Computer System
, Basic Concepts of Computer :: 3
A computer system (fig.1.1) consists of mainly four basic
units; namely input unit, storage unit, central processing
unit and output unit. Central Processing unit further includes
Arithmetic logic unit and control unit, as shown in
Figure 1.2.
A computer performs five major operations or functions
irrespective of its size and make. These are
it accepts data or instructions as input,
it stores data and instruction
it processes data as per the instructions,
it controls all operations inside a computer, and
it gives results in the form of output.
1.4.1 Functional Units:
a. Input Unit: This unit is used for entering data and
programs into the computer system by the user for
processing.
––––
Dotted lines (– – – –) indicate
flow of instruction solid lines
(–––––) indicate flow of data
Fig. 1.2: Basic computer Organization
b. Storage Unit: The storage unit is used for storing data
and instructions before and after processing.
, 4 :: Computer and Office Applications
c. Output Unit: The output unit is used for storing the
result as output produced by the computer after
processing.
d. Processing: The task of performing operations like
arithmetic and logical operations is called processing.
The Central Processing Unit (CPU) takes data and
instructions from the storage unit and makes all sorts of
calculations based on the instructions given and the type
of data provided. It is then sent back to the storage unit.
CPU includes Arithmetic logic unit (ALU) and control unit
(CU)
Arithmetic Logic Unit: All calculations and
comparisons, based on the instructions provided, are
carried out within the ALU. It performs arithmetic
functions like addition, subtraction, multiplication,
division and also logical operations like greater than,
less than and equal to etc.
Control Unit: Controlling of all operations like input,
processing and output are performed by control unit.
It takes care of step by step processing of all operations
inside the computer.
1.4.2 Memory
Computer’s memory can be classified into two types; primary
memory and secondary memory
a. Primary Memory can be further classified as RAM and
ROM.
RAM or Random Access Memory is the unit in a
computer system. It is the place in a computer where
the operating system, application programs and the
data in current use are kept temporarily so that they
can be accessed by the computer’s processor. It is
said to be ‘volatile’ since its contents are accessible
only as long as the computer is on. The contents of
RAM are no more available once the computer is
turned off.
1
BASIC CONCEPTS OF COMPUTER
1.1 INTRODUCTION
A computer is a programmable machine designed to perform
arithmetic and logical operations automatically and
sequentially on the input given by the user and gives the
desired output after processing. Computer components are
divided into two major categories namely hardware and
software. Hardware is the machine itself and its connected
devices such as monitor, keyboard, mouse etc. Software are
the set of programs that make use of hardware for performing
various functions.
1.2 OBJECTIVES
After going through this lesson you would be able to:
familiarise yourself with characteristics of computers
identify the basic components of a computer
explain the importance of various units of a computer
differentiate between system software and application
software
explain the importance of operating system
get acquainted with open source
appreciate the need of computer security
1.3 CHARACTERISTICS OF COMPUTERS
The characteristics of computers that have made them so
powerful and universally useful are speed, accuracy,
diligence, versatility and storage capacity. Let us discuss them
briefly.
,2 :: Computer and Office Applications
Speed
Computers work at an incredible speed. A powerful computer
is capable of performing about 3-4 million simple instructions
per second.
Accuracy
In addition to being fast, computers are also accurate. Errors
that may occur can almost always be attributed to human
error (inaccurate data, poorly designed system or faulty
instructions/programs written by the programmer)
Diligence
Unlike human beings, computers are highly consistent. They
do not suffer from human traits of boredom and tiredness
resulting in lack of concentration. Computers, therefore, are
better than human beings in performing voluminous and
repetitive jobs.
Versatility
Computers are versatile machines and are capable of
performing any task as long as it can be broken down into a
series of logical steps. The presence of computers can be
seen in almost every sphere – Railway/Air reservation, Banks,
Hotels, Weather forecasting and many more.
Storage Capacity
Today’s computers can store large volumes of data. A piece
of information once recorded (or stored) in the computer,
can never be forgotten and can be retrieved almost
instantaneously.
1.4 COMPUTER ORGANIZATION
Fig.1.1: Computer System
, Basic Concepts of Computer :: 3
A computer system (fig.1.1) consists of mainly four basic
units; namely input unit, storage unit, central processing
unit and output unit. Central Processing unit further includes
Arithmetic logic unit and control unit, as shown in
Figure 1.2.
A computer performs five major operations or functions
irrespective of its size and make. These are
it accepts data or instructions as input,
it stores data and instruction
it processes data as per the instructions,
it controls all operations inside a computer, and
it gives results in the form of output.
1.4.1 Functional Units:
a. Input Unit: This unit is used for entering data and
programs into the computer system by the user for
processing.
––––
Dotted lines (– – – –) indicate
flow of instruction solid lines
(–––––) indicate flow of data
Fig. 1.2: Basic computer Organization
b. Storage Unit: The storage unit is used for storing data
and instructions before and after processing.
, 4 :: Computer and Office Applications
c. Output Unit: The output unit is used for storing the
result as output produced by the computer after
processing.
d. Processing: The task of performing operations like
arithmetic and logical operations is called processing.
The Central Processing Unit (CPU) takes data and
instructions from the storage unit and makes all sorts of
calculations based on the instructions given and the type
of data provided. It is then sent back to the storage unit.
CPU includes Arithmetic logic unit (ALU) and control unit
(CU)
Arithmetic Logic Unit: All calculations and
comparisons, based on the instructions provided, are
carried out within the ALU. It performs arithmetic
functions like addition, subtraction, multiplication,
division and also logical operations like greater than,
less than and equal to etc.
Control Unit: Controlling of all operations like input,
processing and output are performed by control unit.
It takes care of step by step processing of all operations
inside the computer.
1.4.2 Memory
Computer’s memory can be classified into two types; primary
memory and secondary memory
a. Primary Memory can be further classified as RAM and
ROM.
RAM or Random Access Memory is the unit in a
computer system. It is the place in a computer where
the operating system, application programs and the
data in current use are kept temporarily so that they
can be accessed by the computer’s processor. It is
said to be ‘volatile’ since its contents are accessible
only as long as the computer is on. The contents of
RAM are no more available once the computer is
turned off.
