Video Chess

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Video Chess Screen ¹

A screenshot of Video Chess (1979), Video Chess from Wikipedia ↩︎

Video Chess,
a chess program for the Atari 2600 Video game console released by Atari in 1978, developed by Larry Wagner and Bob Whitehead (Graphics) in 6502 Assembly, the game AI with the help of Julio Kaplan ¹. According to Larry Wagner, Video Chess was developed as a direct result of a customer who complained that the (original) Video Computer System box showed a picture of chess, but that no chess game existed ². Bank switching ROMs was pioneered for earlier prototypes of Video Chess that were larger than four kilobytes, however the released version ended up fitting the standard 4K size ³.

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Venetian Blinds

The up to eight pieces per row exceeded the sprite limitations, since the Atari 2600 was only able to display three sprites in a row. Bob Whitehead developed a pioneering "venetian blinds" ⁴ animation technique, an algorithm that horizontally reused and vertically interlaced sprites several times while rendering each frame, to give the illusion that the system had more than the maximum number of sprites allowed by the hardware ⁵. However, the computer could not show the position and calculate at the same time.