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Ulf Rathsman ^[1]

Ulf Rathsman,
a Swedish engineer and former professional computer chess programmer. He started chess programming in the 70s, and his first program Dark Horse, written in Fortran and running on a CDC 6600 mainframe computer ^[2] and also on a 36-bit one's complement UNIVAC 1100 ^[3], played the WCCC 1977 in Toronto, the WCCC 1980 in Linz respectively ^[4], and was runner-up at the ECCC 1979.

Photos

WMCCC 1985

in chronological order

Princhess was Rathsman's first program for a microcomputer, written in 6502 Assembly to run on a Commodore 64. In 1981, supported by Johan Enroth, Rathsman became professional chess programmer for dedicated chess computers. Soon after Princhess' success as runner-up at the WMCCC 1981 in Travemünde ^[7], he started collaboration with Peter-Ingolf Gericke und Klaus Heyne within their company Consumenta, merchandising Conchess chess computers manufactured by Wallharn Electronics, Ireland, with Rathsman's 6502 based Princhess program ^[8] ^[9]. After Consumenta's down and out in 1983, Conchess continued under the aegis of Enroth's company, also marketed by Hegener & Glaser within two models of their Mephisto series ^[10] ^[11]. A Conchess computer competed at the WCCC 1983 in New York ^[12].

Princhess became tied World Microcomputer Chess Champion 1984 in Glasgow, where also two Conchess computers competed with the same author involved. In collaboration with co-author Lars Hjörth, Rathsman's next program was Plymate ^[13], competing along with Princhess at the WMCCC 1985, and further the WCCC 1986, the WMCCC 1987 and the WMCCC 1988. Y! (Why Not 88 and 89), also with Lars Hjörth as co-author, and Sandro Necchi as book author, competed the WMCCC 1988 and WMCCC 1989, as well the WCCC 1989 ^[14] . Somewhere in the 90s, Ulf Rathsman retired from computer chess.