Microchess

Microchess is a game developed by for the Apple-1 and Apple II series, as well as many other early personal computer systems. It is believed to be the first commercially-available game for personal computers.

History
Jennings first developed Microchess for the, a demonstration computer released in 1976 by to promote its 6502 microprocessor. It displayed the game status through a very limited set of LEDs. The game was written over 6 months of Jennings' spare time. The source code was originally distributed on paper and managed to fit within 1 kilobyte of RAM. As the Apple-1 kit computer also used a 6502 processor, but with 4 kilobytes of RAM, Jennings permitted early owner Larry Nelson to adapt the code for it. The chessboard was displayed in the form of ASCII text characters on an ordinary television display. When Microchess version 1.5 was ported to the microprocessor and released for the  in 1978, Nelson had it play against the Apple-1 and the result was a draw. Daryl Rictor later adapted a version that could be played over a serial terminal connection.

Version 2.0 was released in 1978 by Personal Software in cooperation with Apple Computer for the more capable Apple II personal computer, taking advantage of its higher memory configuration options (16 KB was required), its high resolution graphics (for the time), and the ability to distribute the software on cassette tape. Microchess became the first computer game to sell over 50,000 copies.