Early Microcomputer Chess
The availability of affordable home computers allowed hobbyists to write their own chess programs. One of the first was Microchess, written in 1976 by Peter Jennings, a recent college graduate.
Jennings sold his program in printed form, which meant that until a cassette tape interface was available, players had to type the program in by hand. In early versions of the program, moves were entered on the calculator-like keyboard of the Kim-1 computer and shown on a 6-digit LED display.
Subsequent versions for the Apple II and the TRS-80 sold several million copies. Some of the early profits were used by the company Personal Software, which had purchased Microchess from Jennings, to help finance the marketing of one of the first spreadsheet programs, VisiCalc.