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 seek financial income by selling the program directly to customers. Since magnetic media were not widely available at the time, the authors placed an advert in Byte Magazine and mailed $15 photocopied listings that would work in any Z80-based microcomputer. Availability of the source code allowed porting to other machines. For example, the March–April 1979 issue of Recreational Computing describes a project that converted Sargon to an 8080 program by using macros. Later the Spracklens were contacted by Hayden Books and a book was published.
Commercialization through electronic media
When magnetic media publishing became widely available, 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. Paul consulted with the Spracklens, both living in San Diego at the time, to make the TRS-80 an instant success with the help of Hayden Book's newly established software division: Hayden Software. Paul was not involved in further refinements to the TRS-80 version due to his reassignment to sea duty shortly after signing the deal with Hayden Software. In the early 1980s SARGON CHESS was ported to several earlier microcomputers, i.e. NASCOM (by Bits & PCs, 1981), Exidy Sorcerer, Sharp MZ 80K, and many others. A complete rewrite was necessary later for the Apple II port, made by Kathleen's brother Gary Shannon. Both were published by Hayden Software.
The Spracklens made some significant improvements on the original program and released Sargon II. This version was ported to a variety of personal computers popular in the early 1980s. and in 1978 defeated AWIT, running on an Amdahl mainframe, at the ninth North American Computer Chess Championship, amazing the audience. That year they published a series of articles in BYTE on computer chess programming. The game engine featured multiple levels of lookahead to make it more accessible to beginning chess players. Even though chess programs of the time could not defeat a chess master, they were more than a match for most amateur players; BYTE in 1980 estimated that Sargon II had a 1500 rating at the highest tournament-time difficulty level, and speculated that it was the best chess program on sale, including dedicated devices. Sargon 2.5, sold as a ROM module for the Chafitz Modular Game System, was identical to Sargon II but incorporated pondering.
In 1980 , the Spracklens' Reversi game finished in first place at a computer tournament at Northwestern University, and in 1981 it finished in third place at the Santa Cruz Open Othello Tournament.
Sargon III was a complete rewrite from scratch. Instead of an exchange evaluator, this version used a capture search algorithm. Also included was a chess opening repertoire. This third version was written originally for the 6502 assembler and was commercially published by Hayden Software in 1983. Some years later the couple was contacted by Apple and after a port for 68000 assembly, Sargon III was the first third-party executable software for the Macintosh.
After the demise of Hayden Software, later chess programs were also released under the name Sargon, including Sargon IV (Spinnaker Software), Sargon V (Activision) and a CD-i title simply named Sargon Chess. The Spracklens concurrently wrote the engines for the dedicated chess computers produced by Fidelity Electronics, which won the first four World Microcomputer Chess Championships.
The Botvinnik game
The famous three-time world chess champion Mikhail Botvinnik played a game with Sargon in 1983 at Hamburg. He did not play his best moves but only tested the program's capabilities. Botvinnik himself was also involved in chess program development.
White: Mikhail Botvinnik
1.c4 e5 2.Nc3 d6 3.g3 Be6 4.Bg2 Nc6 5.d3 Nf6 6.f4 Be7 7.Nf3 O-O 8.O-O Qd7 9.e4 Bg4 10.h3 Bxh3 11.f5 Bxg2 12.Kxg2 Nb4 13.a3 Na6 14.b4 c5 15.b5 Nc7 16.Rh1 a6 17.b6 Nce8 18.Ng5 Qc6 19.Rb1 Bd8 20.Nd5 h6 21.Nf3 Nxd5 22.exd5 Qd7 23.g4 a5 24.Nd2 Ra6 25.Ne4 Rxb6 26.Rxb6 Bxb6 27.f6 Nxf6 28.Nxf6+ gxf6 29.Bxh6 Re8 30.Qf3 Bd8 31.Qh3 Qa4 32.Bd2 Kf8 33.Rf1 Kg8 34.Qh6 Qd7 35.Kg3 f5 36.Rh1 f4+ 37.Kf3 1-0
- Hendrie, Gardner (2005-03-02). "Oral History of Kathe and Dan Spracklen" (PDF). Computer History Museum. Retrieved 2007-02-11.
- Spracklen, Kathy and Dan (October 1978). "First Steps in Computer Programming". BYTE. p. 86. Retrieved 17 October 2013.
- Spracklen, Dan; Kathe Spracklen (1978-11-01). Sargon: A Computer Chess Program. Hayden Book Company. ISBN 0-8104-5155-7.
- It was even ported to the 6809 variety of the FLEX operating system by Brian N. Baily and Charles B. Blish in August 1981, and that port may still be found within this 6809 FLEX emulation
- 28 (1978-12-07). "Tiny Computer Sends Chess Foe Down Tube". Toledo Blade. Retrieved 17 October 2013.
- Spracklen, Dan and Kathy (November 1978). "An Exchange Evaluator for Computer Chess". BYTE. p. 16. Retrieved 17 October 2013.
- Martellaro, John (December 1980). "Sargon II / An Improved Chess-Playing Program for the Apple II". BYTE. p. 114. Retrieved 18 October 2013.
- Martellaro, John (January 1981). "The Newest Sargon - 2.5". BYTE. pp. 208–212. Retrieved 18 October 2013.
- Frey, Peter W (July 1981). "The Santa Cruz Open / Othello Tournament for Computers". BYTE. p. 16. Retrieved 18 October 2013.