# Development of Computers

(i) **Abacus**: It was the first mechanical device developed approximately 3000 years ago. It consists of beads that can slide over horizontally rows fitted with a rectangular wooden frame. The two beads each on the left side of crossbar have a value of five and five beads each on the right of crossbar have a value of one. The counting is done by shifting the beads from one side to another.

(ii) **Napier’s Bone and log:** John Napier developed the idea logarithm. He used logs to transform multiplication problem to addition problem. Napier ’s log later becomes the basis of a well-known invention.The computing machine is known as a slide rule. Napier ’s also devised set of numbering rods known as Napier’s Bones. He could perform both multiplication and division with these bones.

(iii)** Pascal adding** **the machine:** Pascal aFrench mathematician invented the machine in 1641 made of gears which were used for adding numbers quickly. The machine was named adding a machine and it was capable of addition and mechanism principle.

(iv) **Leibnitz Calculator:** Gottfried Leibnitz a German mathematician improved adding a machine and constructed a new machine in 1971 that was able to perform multiplication and division as well.

(v) **Jacquard’s Loom:** Joseph Jacquard manufacture punch cards at the end of American Revolution and used them to control looms in 1801. Thus, entire control weaving process was automatic.

(vi) **Babbage’s Differences Engine:** Before the days of electrical engineering attempts had been made to provide results to a mathematical problem by mechanical means. In the early 19 century the genius man Charles Babbage very popular as the father of Computer, succeed with a machine called Differential Engine.

(vii) **Babbage’s Analytical Engine:** In 1833 began work on his analytical engine intended to be completely automatic. It was to be capable of performing the basic arithmetic problems and it was to do so at a speed of 60 addition per minute.

(viii) **Herman Hollerith’s Machine:** In 1887 an American named Herman Hollerith ’s fabricated what was dreamt of by Charles Babbage. He fabricated the first electromechanical punch cards tabulators that used punch cards for input, output and instruction.

(ix) **Mark -1:** Prof. Howard Aiken came in actual shape only 1943. It was used multiply two 10 digits numbers in five seconds a record at that time. Mark – 1 was the first machine which could perform according to pre-programmed instruction automatically without any manual interface.

(x)** ENIAC:** It was developed in 1946. It was large machine containing 18000 vacuum tubes, weighed 30 tonnes, occupied 1500 square ft or 30 x 50 square ft. It spaces at a small memory of 10 accumulators, 6000 switches, 150000 watts of electricity and cost $ 400000. ENIAC was 5000 times faster than Mark-1. It was based on a decimal system rather than the binary system being used in all other computers.

(xi) **EDSAC:** It was built in 1949 by Prof. Maurice Wilkes at Cambridge University and used mercury delayed Lines for storage. It also used Von Neumann concept of store program.This allows early implementation of program loops.

(xii) **UNIVAC:** It was developed in 1951 by Eckert and Mauchly with the use of 10000 vacuum tubes. This machine was quickly fast with capabilities of working more than one day continuously but the disadvantages of this machine were that it consuming too much power and frequent tube failure.

(xiii) **EDVAC:** It was developed in 1951 with the joining hand of Mauchly and Eckert with Von Neumann. It was the first computer working with stored program concept. It had a control processor and a memory to store data and programs. The binary arithmetic was used in the construction of a computer.

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