Sargon is a line of chess-playing software for personal computers. The original Sargon was written by Dan and Kathleen 'Kathe' Spracklen on a Z80-based computer called Wavemate Jupiter III.
Sargon was introduced at the 1978 West Coast Computer Faire, where it won the first computer chess tournament held strictly for microcomputers. This success encouraged the authors to sell the program directly to customers. Through an ad in Byte Magazine they sold (for $15) photocopied listings of the assembly language program that would work on most any Z80-based microcomputer. Availability of the source code allowed porting to other machines.
A Navy Petty Officer, Paul Lohnes, ported Sargon to the TRS-80, altering both graphics, input, and housekeeping routines leaving the Spracklen's chess-playing algorithm intact. The TRS-80 version became an instant success with the help of Hayden Book's newly established software division: Hayden Software.
Hayden also released Sargon for the Apple II. A complete rewrite was necessary for the Apple II port, and this was done by Kathleen's brother Gary Shannon.
Source: Wikipedia, "Sargon (chess)", available under the CC-BY-SA License.