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owl [soylentnews.org] writes:

Since I discovered Video Chess for the Atari 2600, I found it pretty impressive. However, I believed the game implemented extra RAM memory, but more recently I discovered it worked using only the 128 bytes of memory available, and with a 4K ROM cartridge. That's an impressive achievement for such a small game console, also the rumor of a bug triggered me to reverse engineer this game to see how it works.

Video Chess was developed by Larry Wagner and Bob Whitehead, and released by Atari in 1979. Although the original game is greater than 4K and a bank-switching PCB was created, the final released game was optimized to use only a 4K ROM cartridge.

Video Chess also has the distinction of displaying eight different objects on a screen row using a technique known as Venetian Blinds, where the odd row of the screen would show four chesspieces, and the even row of the screen would show other four chesspieces. This technique allows the Atari 2600 to exceed its own limit of 3 figures per screen row. I won't discuss this technique as it is a video display trick, and in this article I'll concentrate in the AI (Artificial Intelligence) code.

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