UNIT-I:
INTRODUCTION TO COMPUTERS
The word
computer is derived from the word compute. Compute means to calculate. The
computer was originally defined as a super fast calculator. It had the capacity
to solve complex arithmetic and scientific problems at very high speed. But nowadays
computers can perform many other tasks
like accepting, sorting, selecting, moving, comparing various types of information.
They also perform arithmetic and logical operations on alphabetic, numeric and other
types of information. This information provided by the user to the computer is
data.
The information
in one form which is presented to the computer is the input information or
input data.
Q1.Define
computer ? Explain Various characteristics of Computers?
Ans: A Computer is an
electronic device that processes data and converts it into information that is
useful to people.
Characteristics of computer
1) SPEED: The processing
speed of the computer is generally measured in nanoseconds (10-9
seconds). A computer can add two 18 digit numbers within one nano second.
2) ACCURACY: Computers can do
calculations without mistakes. A human being may make mistakes in calculating a
certain range of calculations. But the results given by computer will always be
accurate.
3) RELIABLE: The major reason
behind the reliability of computers is that at hardware level, it does not
require any human intervention between its processing operations. A human being
sometimes knowingly or unknowingly gives results which may be biased. But a
computer being impartial, gives always reliable results which can be relied
upon by all.
4) STORAGE
CAPACITY:
A computer can store large quantity of data. The storage capacity of the
computer can be increased further by secondary memory devices. The data can be
saved and used at any time in future.
5) DILIGENCE: A computer can
do the work for days together. It will work without any boredom and tiredness.
Even if it does the same work many times, it won’t get frustrated like a human
being. Moreover a computer will work with same tempo from beginning to end.
6) VERSATILITY: Computer can
perform multiple tasks simultaneously with equal ease. They feed data,
calculate sums, perform programming and provide multimedia facilities. That is why
they are used in all types of business.
7) NETWORKING
CAPACITY: A
computer can be connected with other computers & share the resources like
data, printer etc. This feature of connectivity with other computers lead to evolution
of computer networking. We can communicate with people in the world because of
networking which ultimately leads to evolution of internet.
8) COMPACTNESS: Computers occupy
very small space in offices or organizations. Now-a-days size of computers has
decreased a lot due to increased technology. The laptop & notebook
computers can be taken outside. They can be operated in cars, railways, buses
etc. Inspite of their small size, their efficiency has increased a lot.
9) EASY
MAINTENANCE: Computers
can be managed easily. They can be repaired immediately. The maintenance cost
of computers is small. They need not require much electricity.
10)
PROGRAMMABLE: The
computer can be programmed to work automatically. They start the work as per
our program and terminate the work until we are satisfied.
Evolution of Computers
Q.2)Explain
evolution of computers or history of computers?
Ans: Computers
have evolved over the years from simple mechanical device to powerful digital
computers.
1. Abacus Abacus was the first calculating machine used for counting. Abacus was mainly used for addition and subtraction.
2.Napier’s
bones: The Napier’s Bones has a set of bones. It was invented by John
Napiers. He invented this to perform multiplication.
3. Slide rule The Slide Rule was invented by ‘William - Ought red’. The slide rule is has two sets of scales. These scales are useful to perform multiplication and division.
The first
mechanical device used for addition was invented by Pascal in 1642.
→ This machine
was improvised by Baron Gottfied in 1671 and invented a device capable of
performing multiplication.
→ In 1880,
Herman Hollerith introduced the concept of punched cards for providing input.
This concept was continuously adopted till late 1970s.
→ Charles
Babbage is considered to be the father of modern digital computers
• He designed “Difference Engine” in
1822 .
• He designed a fully automatic
analytical engine in 1842 for performing basic arithmetic functions
His efforts
established a number of principles that are fundamental to the design of any
digital computer
Some Well
Known Early Computers
• The Mark-I Computer It was a machine of length 50 feet and
height 8 feet capable of performing addition, subtraction, multiplication and
division.
BLOCK DIAGRAM OF THE COMPUTER
Q3.)Explain
Block Diagram of computer?(VIMP)
B) CPU
(Central Processing Unit) : CPU is the brain of any computer system.
It Coordinates all computer operations and Perform arithmetic and logical
operations on data. It controls the operation of all parts of the computer.
CPU itself has the
following three components
ALU (Arithmetic
Logic Unit) :This
unit consists of two subsections namely, Arithmetic Section and Logic Section
Arithmetic
Section:
Function of arithmetic section is to perform arithmetic operations like
addition, subtraction, multiplication, and division. All complex operations are
done by making repetitive use of the above operations.
Logic Section: Function of
logic section is to perform logic operations such as comparing, selecting,
matching, and merging of data.
Memory Unit or
Storage Unit The electronic
storage are of a computer is known as Memory. It is also known as internal
storage unit or the main memory or the primary storage or Random Access Memory
(RAM).
Computers memory
is of two types:
1.Primary
Memory ( or )Main Memory
2.Secondary
Memory
Main memory
stores the programs and data that are currently being used by the computer. It
holds data and programs temporarily.
Secondary memory
stores the data permanently. It is also known as auxiliary memory. It is much
less expensive.
Control Unit: Control Unit of
a computer system manages and coordinates the operations of all other
components of the computer system
C) Output Unit : Output devices can display the resulting information to the user. Monitors and Printers are commonly used output devices.
Generations of Computers:
Q4.) Explain Generations of Computers?
Ans: The evolution of
computers can be divided into the following Five generations
First Generation 1940-1956: The computers of the period
1940-1956 are considered as the First Generation Computers. The first
generation computers were slow, huge and expensive. These computers used vacuum
tubes. First generation computers operated only on machine
language.
Example: UNIVAC and
ENIAC.
Second Generation - 1956-1963: The
computers of the period 1956-1963 are considered as the Second Generation
Computers. These computers used transistors. These computers used
assembly language.
In the second
generation computers:
· • Size of the computers started reducing
· • Concept of stored program emerged
· • High level languages were invented.
Example: IBM 7094
series, IBM 1400 series and CDC 164etc.
Third Generation - 1964-1971 : The
computers of the period 1964-1971 are considered as the Third Generation
Computers. These computers used Integrated circuits (ICs).
· •Phenomenal increase in computation speed
· •Substantial reduction in size and power consumption of the machines
· •Commercial production of computers.
Example: IBM 370, UNIVAC
1108etc.
Fourth
Generation - 1971-Present : The computers of the period 1971-present
are considered as the Fourth Generation Computers. These computers used microprocessors.
· •Use of Very Large Scale Integration
· •Invention of microcomputers
· •Introduction of Personal Computers
· •Networking
· •Fourth Generation Languages.
Example: Apple Macintosh
and IBM PC.
Fifth Generation
- Present and Beyond: The computers of present and beyond are considered
as the Fifth Generation Computers. These computing devices are based on
‘artificial intelligence’. Many advances in
the science of computer design and technology are coming together to enable the
creation of fifth generation computers.
Example: IBM Watson
computer, SGI Origin 2000 , PARAM 10000
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