All generations have certain things they get misty eyed about and feel an irresistible urge to share it with younger people in a desperate attempt to make them understand just how groundbreaking and wonderful it was back in the day. For some it was having the whole street round to the one house with a television to watch the Coronation, for others it’s the first time they saw the T-Rex demo on the original Playstation, no doubt for some toddlers alive today it will be the first time they teleported to school or make a holographic phone call, but for a select and fortunate few, it’s the sense of wonder and astonishment that anyone could program a chess game using just 1K of memory, so much so that some call 1K Chess the “greatest program ever written”.


1K ZX Chess was only called 1K because it was for playing on the ZX81, the basic unexpanded version of the ZX81 had a massive 1K (1,024 bytes) of RAM memory. By today’s standards, with our terabyte hard drives, this may seem laughable, but it’s surprising how much fun can be had with 1,024 bytes, don’t even get me started on the 16K RAM pack and 3D Monster Maze. 1K chess managed to fit a chess game into the ZX81 with room to spare, just using 672 bytes of code.

To put this into perspective, this small article, saved as a text file, would be 2,339 bytes. UK coder David Horne coded a Chess game in less than that, and it’s no exaggeration to say it is one of the most elegant, beautiful things ever created. It has a chess board, including (most of) the rules and even had a computer opponent to play against, not a very good opponent, but what do you expect for 672 bytes?

Chess for the ZX81 was originally released in the shops in 1982 to buy on audio cassette and download to your ZX81, but the full code was later published in Your Computer magazine and could be run on your computer by typing it in, line by line. It’s only 672 bytes, it didn’t even take that long to type it in.

For 33 long years 1K ZX Chess has held the trophy for the smallest-sized chess computer program, but in January 2015 French coder Olivier Poudade beat it by creating BootChess using only 487 bytes of code.

What we really need to do now is have BootChess play 1K ZX Chess and see who wins.

[Image via Russ Payne]