Colossus Chess

Colossus Chess

Company type	Software
Industry	Computer chess software
Founded	1984
Founder	Martin Bryant
Headquarters	United Kingdom
Products	Chess software programs for various home computer systems

Colossus Chess represents a collection of chess software programs created by Martin Bryant and released commercially across various home computer systems during the 1980s. Published by CDS Micro Systems and English Software, these titles catered to the expanding digital chess audience, compatible with platforms such as Acorn Electron, Amiga, Amstrad CPC, Apple II, Atari ST, BBC Micro, Commodore 64, MS-DOS, MSX, and ZX Spectrum. The series' initial run extended from 1984 through 1990, with subsequent updates under the Colossus Chess UCI label from 2006 to 2008, demonstrating ongoing efforts to sustain its competitiveness in the realm of computer chess.

History

In 1983, Bryant introduced Colossus Chess, building upon his award-winning program White Knight Mk 11, which had secured victory at the 1983 European Microcomputer Chess Championship. Originally developed on an Apple II, its first commercial launch occurred in 1984 as Colossus Chess 2.0 for the Commodore 64 via CDS Micro Systems. Later editions expanded support to various 8-bit machines: version 3.0 appeared on Atari 8-bit computers (published by English Software), followed by version 4.0 in 1985 across multiple platforms (published by CDS). Notably, the Acorn Electron edition required utilizing part of the screen memory as working storage.

The software incorporated time-controlled matches with game clocks, an extensive opening repertoire containing approximately 3,000 positions, and a problem-solving feature capable of addressing standard mates, selfmates, and helpmates. With Colossus Chess 4.0, enhancements included pondering during the opponent’s turn and a three-dimensional chessboard visualization. Each iteration was coded in assembly language tailored to the respective CPU; for instance, the ZX Spectrum version evaluated roughly 170 positions per second.

Distinguishing itself from many contemporaries, Colossus implemented all official chess regulations, including underpromotion options, the fifty-move rule, draw by repetition, and draws due to insufficient material. Additionally, it was proficient in executing all fundamental checkmates, even managing the complex bishop and knight checkmate.

Colossus Chess X

The Colossus Chess X editions were adapted for the Atari ST in 1988, the Amiga in 1989, and the IBM PC in 1990. These releases featured four distinct chess sets along with improved graphical elements developed in collaboration with Gary Thomlinson and Carl Cropley. The opening library was significantly expanded to encompass about 11,000 positions, while the program gained capabilities to learn from previous games.

UCI version

Following a development hiatus between 1991 and 2005, Martin Bryant introduced a new Windows-compatible version supporting the Universal Chess Interface. Initially programmed in C#, it was later rewritten in C to optimize performance before being publicly distributed in 2006. , version 2025a is the most recent release.

Reception

Info evaluated Colossus Chess IV for the Commodore 64 with a three-star rating out of five. The review observed that while it lacked some visual appeal compared to Chessmaster 2000, it offered superior playability and supported both keyboard and joystick input. However, it noted challenges related to shifted keyboard commands and advised users to keep a quick-reference guide handy.

External links

• Official Colossus website (archived)
• Colossus Chess 4.0 user manual (C64)