**Computer History**

**Abacus**

Abacus is first calculating machine invented by human beings almost 3000 years ago. The purpose of abacus was to add, subtract, multiply, divide, large numbers. It may have originated in China or Egypt of Greece.

It was constructed by wooden frame and that frame is divided into two parts, the lower part is called earth and upper part is called heaven. Small rods are adjusted in frame and small beads are adjusted in it. Two beads are in heaven and 5 beads are in earth. For calculation the beads can be move to mid bar.

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**Pascaline**

This is first true calculating machine and invented by Blaise Pascal in 1642. Pascal is French mathematician. In this machine, the numbers were entered by dialing series of numbered wheels and series of gears. The numbers 0 to 9 are assign in wheel. When the first wheel made a complete turn from 0 to 9. It automatically cause the second wheel to advanced to the next number and so on. Pascaline could add and subtract by the movement of wheels. This machine can not perform. multiplication and division that was its great limitation. To remove this limitation, another scientist Gottfried Wilhelm von Leibniz invented another calculating machine called stepped Reckoner in 1673. His machine can perform addition, subtraction, multiplication, division as well as square root.

**Babbage and his Engine**

Charles Babbage is called father of computer science because modern computers are based on his idea.Babbage was Professor of Mathematics at Cambridge University and started a small model of his “Differential Engine”. This machine gives accurate result up to 20 decimal places. This machine was never completed because of mechanical problems. The important concept of Babbage which is implemented in modern computer is concept of input, output, and storage. According to his concept, the data or information is given to machine from input device, after processing, or calculation the result is given from output device. The modern computers are also based on his concept.

**Neumann and store program concept**

In computer technology, John von Neumann add a new concept which play important role to develop more reliable, fast, secure, small sized computer. His suggestions are:

- Binary number system should be used in computer system. (this is not new concept but he suggest to use it)
- Computer instructions as well as data being manipulated could be stored internally (inside small and fast memory) in the machine.

The first machine that use Neumann store program concept is EDVAC (**E**lectronic **D**elay **S**torage **A**utomatic **C**omputer) in 1952. In this system, when we input the data inside computer that data is stored inside computer and all related programs are also stored inside it. To process the data, computer takes data from memory and related instruction from fixed memory locations. Modern computer as well as calculator or any electronic programmable devices even a mobile system store instruction inside it before processing.

**UNIVAC**

J. Presper Eckert and John W. Mauchly founded their own company in 1946 and start work to develop this computer. In 1951, first UNIVAC-1 was started to work in census. It stands for **UNI**versal **A**utomatic **C**omputer. This is a first commercially used electronic computer. This computer was more reliable, accurate and fast machine for data manipulation.