I developed Colossus Chess in 1983 from my existing White Knight chess program. It used various forward pruning techniques to achieve deeper, narrower tree searches than its earlier full width cousin and had a more sophisticated evaluation function. Over the following few years it was published for a large number of 8-bit micros including the Commodore 64 (the original version 2 and later version 4), BBC Micro, Acorn Electron, Apple ][, Atari, Amstrad CPC, Amstrad PCW, Sinclair Spectrum, MSX and probably a few more too! Later it was released for the 16-bit micros Atari ST, Commodore Amiga and IBM PC (now christened version 'X'). It became one of the largest selling chess programs of all time. In all cases it was written in the assembly language of the appropriate CPU. The graphics on the later 16-bit versions were developed with the assistance of Gary Thomlinson and Carl Cropley. No work was done on the program from 1991 until 2005. However, Guildhall Leisure released a rebadged version called Colossus Chess 2000.

Colossus took part in the 1984 World Microcomputer Chess Championship in Glasgow.

In 2004 I started work on a completely new version conforming to the UCI protocol.

Boxes

Screenshot