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Unit-1: Introduction to Computer System
Contents: Introduction to Computer, Characteristics, Applications and Classification of Computer, Mobile
Computing, Anatomy of a Digital Computer, Computer Architecture, Memory and its Classification, Input
and Output Devices, Interfaces.
Introduction
A computer is an electronic machine that takes input from a user, processes the given input and
generates output in the form of useful information.
A computer accepts inputs in many forms such as data, programs and user reply.
DATA -> raw details that require processing for generating useful information
PROGRAM -> set of instructions that can be executed by computer in sequential or non-sequential order
USER REPLY -> input provided by the user in response to query asked by computer
Characteristics
1. Speed
Computer can do any tasks in fractions of second. The speed of the computer is based
on its hardware configuration.
2. Storage Capacity
A computer can store a huge amount of data in many different formats.
3. Accuracy
A computer carries out any calculation with a 100% accuracy. However, this depends on
the configuration of the system and instruction from the user.
4. Reliability
A computer processes results with 0 error. Mostly the error generated in the computer
is due to user’s fault.
5. Diligence
Computer can be set to perform repetitive tasks for numerous times and the result will
always be displayed with the same accuracy and efficiency. Computers aren’t affected
by human traits like dizziness, fatigue, distraction, tiredness, etc.
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, Page 2 of 14
6. Versatility
The same computer can be used for many different tasks for many different purposes.
Evolution of Computer
1. Mechanical Era
2. First Generation Computer
Employed: 1940 – 1956
Technology used: Vacuum Tube
Tasks done: Mathematical Calculation
Advantages: fast computing in their time, executed complex mathematical problems in
efficient manner
Disadvantages: Operated on machine language (0s and 1s), not flexible for running
different applications, large and bulky in size and consumed high power
3. Second Generation Computer
Employed: 1956 – 1963
Technology Used: Transistors
Improvements: development of printer, secondary storage, operating system
technology, replacement of machine language with assembly language
Tasks done: Mathematical Calculation
Advantages: fast computing in their time, easy to program (assembly language), smaller
in size and consumed less power
Disadvantages: I/O devices not improved to considerable extent, generated huge
amount of heat, beyond the access of households
4. Third Generation Computer
Employed: 1964 – 1975
Technology Used: Integrated Circuits (I.C.)
Improvements: I.C.s made the size of computer smaller, performance efficient and
faster and reliable
Advantages: computational time reduced to nano-seconds, use of high-level language
Disadvantages: low storage, costly
5. Fourth Generation Computer
Employed: 1975 – 1989
Technology Used: LSI, VLSI
Copyright ©| Note Bahadur | All Rights Reserved
Unit-1: Introduction to Computer System
Contents: Introduction to Computer, Characteristics, Applications and Classification of Computer, Mobile
Computing, Anatomy of a Digital Computer, Computer Architecture, Memory and its Classification, Input
and Output Devices, Interfaces.
Introduction
A computer is an electronic machine that takes input from a user, processes the given input and
generates output in the form of useful information.
A computer accepts inputs in many forms such as data, programs and user reply.
DATA -> raw details that require processing for generating useful information
PROGRAM -> set of instructions that can be executed by computer in sequential or non-sequential order
USER REPLY -> input provided by the user in response to query asked by computer
Characteristics
1. Speed
Computer can do any tasks in fractions of second. The speed of the computer is based
on its hardware configuration.
2. Storage Capacity
A computer can store a huge amount of data in many different formats.
3. Accuracy
A computer carries out any calculation with a 100% accuracy. However, this depends on
the configuration of the system and instruction from the user.
4. Reliability
A computer processes results with 0 error. Mostly the error generated in the computer
is due to user’s fault.
5. Diligence
Computer can be set to perform repetitive tasks for numerous times and the result will
always be displayed with the same accuracy and efficiency. Computers aren’t affected
by human traits like dizziness, fatigue, distraction, tiredness, etc.
Copyright ©| Note Bahadur | All Rights Reserved
, Page 2 of 14
6. Versatility
The same computer can be used for many different tasks for many different purposes.
Evolution of Computer
1. Mechanical Era
2. First Generation Computer
Employed: 1940 – 1956
Technology used: Vacuum Tube
Tasks done: Mathematical Calculation
Advantages: fast computing in their time, executed complex mathematical problems in
efficient manner
Disadvantages: Operated on machine language (0s and 1s), not flexible for running
different applications, large and bulky in size and consumed high power
3. Second Generation Computer
Employed: 1956 – 1963
Technology Used: Transistors
Improvements: development of printer, secondary storage, operating system
technology, replacement of machine language with assembly language
Tasks done: Mathematical Calculation
Advantages: fast computing in their time, easy to program (assembly language), smaller
in size and consumed less power
Disadvantages: I/O devices not improved to considerable extent, generated huge
amount of heat, beyond the access of households
4. Third Generation Computer
Employed: 1964 – 1975
Technology Used: Integrated Circuits (I.C.)
Improvements: I.C.s made the size of computer smaller, performance efficient and
faster and reliable
Advantages: computational time reduced to nano-seconds, use of high-level language
Disadvantages: low storage, costly
5. Fourth Generation Computer
Employed: 1975 – 1989
Technology Used: LSI, VLSI
Copyright ©| Note Bahadur | All Rights Reserved
