__DEFINITION:__Computer is an electronic device use to perform high level arithmetical and logical operations at a very high speed according to the instructions provided by the user.

**MEANING OF COMPUTER:**

__HISTORY OF COMPUTER__Probably during 600 B.C., Abacus, an improved system of computation was developed in which the numbers were represented by the number of beads placed on a rack and their position. Simple addition and subtraction could be done using this by properly positioning the beads on the rack. The name Abacus came from the Greek word 'Abakos'. This is also known as 'Soroban Computer'.

A Scottish mathematician John Napier(1550-1617), developed a cardboard multiplication calculator during early seventeenth century. In the year 1642, a French mathematician

John Napier |

A major development in computer took place in the nineteenth century. Herman Hollerith, a German scientist, developed the punched card system. He utilised

Herman Hollerith |

**(1792-1871), an Englishman, developed the first form of a modern digital computer. He is the first man who give a definition of a computer. He is known as the**

*Charles Babbage***. Earlier in 1822, Babbage designed a 'Difference Engine' which could compute various reliable mathematical and statistical tables. In 1842, he developed a new idea of automatic analytic engine which would be capable of performing basic arithmetical process. Unfortunately he could not develop the model of his analytical engine due to the constrains of precision engineering methodology, but gave the fundamental idea of a digital computer. He also specified the definition of a computer.**

*"Father of Computer"*Charles Babbage |

After the development of the first form of computer according to the concept of Charles Babbage, the right path for the development of computer science could be seen and researches had been started to design the improved version of modern computer.

The first fully automatic calculating machine, known as the Mark-1 computer, was designed by Howard A. Aiken in collaboration with International Business Machines(IBM) Corporation(1937-1944). It was an automatic sequence controlled calculator and its design was based on the technique of punched card machinery. It was a very big machine(50 feet in length and 8 feet in height) accommodating about 3000 electrically operated switches. it was basically an electromechanical device. It could perform all fundamental mathematical calculations together with table reference. Maximum permissible data size, the machine could handle was 23 decimal digits. Its operating speed was 0.3 seconds and 4.5 seconds for adding and subtracting two numbers respectively.

During 1939-1942, Dr. John Atanasoff and his assistant Clifford Berry developed an electronic machine using 45 vacuum tubes and several bank of capacitors. The machine was capable of solving certain mathematical equations. The machine was known as Atanasoff-Berry computer or ABC in short.

In the year 1946, the Electronic Numerical Integrator and Calculator or in short ENIAC was developed by the Moore School of Engineering, University of Pennsylvania, USA. The team was headed by prof. J.P. Eakert and John Mauchly. The size of the machine was 20*40 square feet and it utilized 18000 vacuum tubes. It could add two numbers in 200 microseconds and multiply numbers in 2000 microseconds. Though ENIAC was much faster in operation than the earlier machines, it had two major limitations, a>very limited information storage capacity, and b>dependence of program execution on hardware setting.

The problems of ENIAC had been overcome when Dr. John Von Neumann introduced the Electronic Discrete Variable Automatic Computer(EDVAC) utilising the new concept of 'stored program' during 1946-1952. He is the pioneer to introduce the concept of binary mathematics in computer. He pointed out that a>Each and every number could be represented by using a set of 0 and 1, and b>Both the instructions and data could be coded in binary and supplied to the computer in a meaningful manner. All computer including supercomputer of the present days, work using the binary system developed by Dr. Neumann.

It is interesting to mention here that while Dr. Neumann was busy in developing EDVAC in USA, Prof. Maurice Wilkes of Cambridge University, UK was busy in developing "Electronic Delay Storage Automatic Calculator"(EDSAC) with a group of scientists. The machine executed its first program in 1949. In this machine, the speeds of operation were 1500 secs and 4000 secs for addition and multiplication of two numbers respectively.

Almost at the same time (1948), another group of scientists from Manchester University, UK, headed by Prof. M.H.A. Neuman developed an experimental form of a computer utilising the 'stored program concept'. The machine known as Manchester Mark-1 was capable of handling numbers of 31 binary digits with a limited capacity of storage of only 32 words.

The UNIVAC-1 computer, the first digital computer in true form was developed in 1951. This Universal Automatic Computer was installed in the Census Bureau. later, General Electric Corporation used UNIVAC-1 commercially. Shortly IBM Corporation developed different improved versions of commercial computers like IBM-650 and the era of commercial computers had been started. The custom of referring to the computer era intervals of Generation come into being only after 1964 with the improvement of technology in computer architecture. Initially, the term 'Generation' was used to distinguish between varying hardware technologies. But nowadays, it has been extended to include both hardware and software.

__To know more click the below link.....__http://computinga2z.blogspot.in/2012/11/generation-of-computers.html

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