Strachey's draughts program
Ported to the Ferranti Mark 1, Christopher Strachey's program played a full game of draughts at a reasonable speed.
Why it matters
The first program to finish a game showed that the bottleneck was not the search idea but the machine's memory.
Strachey first wrote the program for the Pilot ACE. On 15 May 1951 he told Turing that his first version for the Manchester machine was far too slow and did not use its large storage, being only a slight modification of the ACE design. The surviving coding sheets are dated June and July 1952, and one recorded run 10 July. At the ACM meeting of September 1952 Strachey reported that the program would play a complete game of draughts at a reasonable speed. By his own account, though, it played tolerably only until the end game, and the game he printed was stopped once the outcome was obvious; the reconstructed code has nothing that detects the end of a game or names a winner. Strachey later used the same machine for his love-letter generator.