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# History of The Development of Computers

## HISTORY  OF THE DEVELOPMENT OF COMPUTERS

In  beginning,  there  were  no  computers.  To  add  or  subtract  ,  man  used  his  fingers  and  toes.  Abacus  is known to  be  the    first  mechanical  calculating  device.  The  main  purpose  of  abacus  was  that  additions  and  subtraction coud  be  performed  quickly.  Abacus  was  developed  by  the  Egyptians  in  the  10th  centuary  B.C,  but  the  final structure  was  given  in  the  12th  centuary  A.D.  by  the  Chinese  educationists.  Abacus  is  made  up  of  a  frame  in which rods are fitted across with rounds beads sliding on the rod.

Napier
Napier’s Bones in an Abacus invented by John Napier.Napier’s used the bone rods for counting purpose where numbers were printed on them.  With the help of these  rods ,one could do addition,  subtraction, multiplication and division speediy.
Pascal’s Calculator
Pascal’s calculator  called ‘Pascaline’ In the year 1642, Blaise Pascal a French scientist  invented  an adding machine  called  Pascal’s calculator, which represents the position of digit with the help of gears in it.  Though these machines were early forerunners to computer engineering, the calculator failed to be a great commercial success.
Leibniz Calculator
Leibniz  was  successfully introduced as a calculator  onto the market in the year 1646. It was designed further in  1673  but  it  took  until  1694  to  complete.  The  calculator  could  perform  the  basic  mathematical  operations such as  add, subtract, multiply, and divide.  Wheels were placed at right angles which could be displaced by a special stepping mechanism.
Analytical Engine “The first Computer
This  analytical  engine,  the  first  fully- automatic  calculating  machine,  was  constructed  by  British  computing pioneer  Charles  Babbage  (1791-1871),  who  first  conceived  the  idea  of  an  advanced  calculating  machine  to calculate  and  print  mathematical  tables  in  1812.  This  Analytical  Engine  incorporated  an  arithmetic  logic  unit, control  flow  in  the  form  of  conditional  branching  and  loops,  and  integrated  memory,  making  it  the  first  design for a general- purpose computer that could be described in modern terms as  Turing -complete.

FIVE GENERATIONS OF COMPUTERS
First Generation of Computers (1942-1955)
The  beginning  of  commercial  computer  age  is  from  UNIVAC  (Universal  Automatic  Computer).  The  first generation  computers  were  used  during  1942-1955.  They  were  based  on  vacuum  tubes.  Examples  of  first generation computers are  ENIVAC  and UNIVAC-1.
• •  Vacuum tubes were the only electronic component available during those days.
• •  Vacuum tube technology made possible to make electronic  digital computers.
• •  These computers could calculate data in millisecond.

• •  The computers were very large in size.
• •  They consumed a large amount of energy.
• •  Non-portable.
• •  Limited commercial use.
• •  Very slow speed.
• •  Used machine language only.
• •  Used magnetic drums which provide very less data storage.

## Second Generation Computers (1955-1964)

The  second generation computers  used transistors.  The size of the computers  was decreased  by replacing  vacuum  tubes with transistors. The  examples  of  second  generation  computers  are  IBM7094 series, IBM1400 seriesand CDC164  etc.

• •  Smaller in size as compared  to the first generation computers.
• •  Used less energy and were not heated.
• •  Better speed and could calculate data in microseconds
• •  Used faster peripherals like  tape drives, magnetic disks, printer etc.
• •  Used Assembly language instead of Machine language.

• •  Cooling system was required
• •  Constant maintenance was  required
• •  Only used for specific purposes
• •  Costly and not versatile

## Third Generation Computers (1964-1975)

The  Third generation computers  used  the  integrated  circuits  (IC).  The  first  IC  was  invented  and  used  in  1961. The  size  of  an  IC  is  about  ¼  square  inch.  A  single  IC  chip  may  contain  thousands  of  transistors.  The  computer became  smaller  in  size,  faster,  more  reliable  and  less  expensive.  The  examples  of  third  generation  computers are  IBM370, IBM System/ 360, UNIVAC1108 and  UNIVACAC9000 etc. An integrated circuit(IC),  sometimes called a chip or microchip,  is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated.

• •  Smaller in size as compared  to previous generations.
• •  More reliable.
• •  Used less energy.
• •  Better speed and could calculate data in nanoseconds. Disadvantages :
• •  Air conditioning was required.
• •  Highly sophisticated technology required for the manufacturing of IC chips.

## Fourth Generation Computers (1975-Present)

The  fourth generation computers  started with  the  invention of Microprocessor.  The  Microprocessor contains thousands of ICs.   The LSI (Large Scale Integration)  circuit and  VLSI  (Very Large Scale Integration) circuit was designed. It greatly  reduced the size of computer.  The size of modern Microprocessors is usually one square  inch.  It  can  contain  millions  of  electronic  circuits.  The  examples  of  fourth  generation  computers  are Apple Macintosh & IBM PC.

• •  More powerful and reliable  than previous generations.
• •  Small in size
• •  Fast processing power with less power consumption
• •  Fan for heat discharging and thus to keep cold.
• •  Cheapest among all generations
• •  All types of High level languages can be used in this type of computers