Alan Turing: Codebreaker and Computer Pioneer
B.J. Copeland and Diane Proudfoot recall the contribution to the war effort in 1939-45 of the British computer scientist.
In 1936, mathematician Alan Turing dreamed up the principle of the modern computer – the idea of controlling its operations by means of a program of coded instructions stored in memory. Yet his idea was not turned into a reality for more than ten years – during which Turing made a vital contribution to the Allied victory in the Second World War.
Before the start of war Turing turned to the problem of breaking Enigma, the coding machine adopted by the German navy in 1926, followed by the army in 1928 and the air force in 1935. The Enigma operator typed the plain message at the keyboard, and each time he pressed a key, a letter on a lampboard lit up. Each time the operator pressed a key, the internal wiring of the machine altered, thanks to three rotating wheels at the heart of the machine; so that if the operator repeatedly keyed A (for example) a succession of different letters would light up. At the receiving end, the cipher text was typed into a machine set up in exactly the same way as the sender’s, and the letters of the plain text lit at the lampboard.
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