Kuro5hin Kuro5hin: Assembly program by David Horne, which is run on the ZX81 with just 1k of memory. (Chess) http://www.kuro5hin.org/story/2001/8/10/12620/2164
Full ZX-81 Chess in 1K Full ZX-81 Chess in 1K: Describes a 672 bytes program that plays chess. (Chess) http://users.ox.ac.uk/~uzdm0006/scans/1kchess/