One of the earliest machines designed to assist people in calculations was the abacus which is still being used some 5000 years after its invention.

In 1642 Blaise Pascal (a famous French mathematician) invented an adding machine based on mechanical gears in which numbers were represented by the cogs on the wheels.

Englishman, Charles Babbage, invented in the 1830's a "Difference Engine" made out of brass and pewter rods and gears, and also designed a further device which he called an "Analytical Engine". His design contained the five key characteristics of modern computers:-

An input device Storage for numbers waiting to be processed A processor or number calculator A unit to control the task and the sequence of its calculations An output device

Augusta Ada Byron (later Countess of Lovelace) was an associate of Babbage who has become known as the first computer programmer.

An American, Herman Hollerith, developed (around 1890) the first electrically driven device. It utilised punched cards and metal rods which passed through the holes to close an electrical circuit and thus cause a counter to advance. This machine was able to complete the calculation of the 1890 U.S. census in 6 weeks compared with 7 1/2 years for the 1880 census which was manually counted.

In 1936 Howard Aiken of Harvard University convinced Thomas Watson of IBM to invest $1 million in the development of an electromechanical version of Babbage's analytical engine. The Harvard Mark 1 was completed in 1944 and was 8 feet high and 55 feet long.

At about the same time (the late 1930's) John Atanasoff of Iowa State University and his assistant Clifford Berry built the first digital computer that worked electronically, the ABC (Atanasoff-Berry Computer). This machine was basically a small calculator.

In 1943, as part of the British war effort, a series of