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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 [1] and also on a 36-bit one's complement Univac 1100 [2], played the WCCC 1977 in Toronto, the WCCC 1980 in Linz respectively [3], and was runner-up at the ECCC 1979.
Ulf Rathsman [4]


in chronological order

Dedicated Computers


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 [5], 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 [6] [7]. 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 [8] [9]. A Conchess computer competed at the WCCC 1983 in New York [10].

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 [11], 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 [12] . Somewhere in the 90s, Ulf Rathsman retired from computer chess.


Lars Hjörth, David Kittinger, Kaare Danielsen, Ulf Rathsman, WMCCC 1985 [13]

Photos & Games

WCCC 1986, Plymate vs. Mephisto X, Ulf Rathsman, Richard Lang and Ossi Weiner [14]
[Event "WCCC 1986"]
[Site "Cologne, Germany"]
[Date "1986.06.12"]
[Round "2"]
[White "Plymate"]
[Black "Mephisto X"]
[Result "1-0"]
1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Bf5 5.Ng3 Bg6 6.Bc4 e6 7.N1e2 Nf6 8.Nf4 Bd6 
9.Nxg6 hxg6 10.O-O b5 11.Be2 Ne4 12.Bg4 Qh4 13.Bh3 Ng5 14.Bxg5 Qxg5 15.Qd3 Nd7 
16.Ne4 Qd5 17.a4 Bc7 18.axb5 cxb5 19.Nc3 Qd6 20.f4 b4 21.Nb5 Qb6 22.Qc4 Kd8 
23.Kh1 a6 24.Nxc7 Qxc7 25.Qb3 Qc6 26.Qxb4 Rxh3 27.Qa5+ Ke8 28.d5 Qxc2 29.gxh3 
Qe4+ 30.Kg1 Qd4+ 31.Rf2 exd5 32.Qc7 Qe3 33.Qd6 Rb8 34.b4 Qe4 35.Qxa6 Qxb4 36.Qc6 
Qd4 37.Re1+ Kd8 38.Qc2 Nf6 39.Rc1 Qb6 40.Kh1 Ne4 41.Rff1 Rb7 42.Qc8+ Ke7 43.Rfe1 
Rd7 44.Qh8 Qf6 45.Rf1 Rd8 46.Qh7 Kd7 47.Rcd1 Nc3 48.Rd3 Ra8 49.Rc1 Rc8 50.Re1 d4 
51.Rg3 Ra8 52.Rg2 Nd5 53.f5 Ne3 54.Rd2 Qc6+ 55.Kg1 Qc3 56.Rde2 Ra1 57.Qh4 gxf5 
58.Rxa1 Qxa1+ 59.Re1 Qb2 60.Qg3 g6 61.Qf3 f6 62.Qa8 f4 63.Ra1 Qb5 64.Qe4 Qg5+ 
65.Kh1 Qd5 66.Qxd5+ Nxd5 67.Rd1 Ke6 68.Rxd4 Ke5 69.Ra4 Nc3 70.Ra3 Nd5 71.Kg1 Ke4 
72.Kf2 g5 73.h4 Ne3 74.Ra4+ Kf5 75.h5 Ng4+ 76.Kg2 Ne5 77.Ra7 Ng4 78.h3 Nh6 79.Rh7 
Ng8 80.h6 Kg6 81.Rg7+ Kxh6 82.Rxg8 Kh7 83.Rc8 f5 84.Rf8 Kg7 85.Rxf5 Kg6 86.Rd5 

External Links


  1. ^ Peter Jennings (1978). Microchess 1.5 Versus Dark Horse. BYTE, Vol. 3, No. 3
  2. ^ 3rd World Computer Chess Championship - Linz 1980 (ICGA Tournaments)
  3. ^ Dark Horse' ICGA Tournaments
  4. ^ Image cropped from Tidskrift för Schack utges av Sveriges Schackförbund, No. 9, November, 1982, pg. 285, Den "svensktillverkade" schackdatorn Conchess konstruktörer, Ulf Rathsman och Johan Enroth, pdf
  5. ^ Princhess' ICGA Tournaments
  6. ^ ConchessSchachcomputer.info Wiki (German)
  7. ^ Karsten Bauermeister (1998). Die Geschichte der Conchess-Schachcomputer. Computerschach und Spiele, Heft 4, August-September 1998
  8. ^ Mephisto B&PSchachcomputer.info Wiki
  9. ^ Mephisto MM IISchachcomputer.info Wiki
  10. ^ Conchess' ICGA Tournaments
  11. ^ Plymate's ICGA Tournaments
  12. ^ Y!'s ICGA Tournaments
  13. ^ László Lindner, A SZÁMÍTÓGÉPES SAKK KÉPEKBEN című melléklete - The pictures of the Beginning of Chess Computers
  14. ^ Computerschach Weltmeisterschaft / World Computer Chess Championship (WCCC) from Schachcomputer.info - Wiki

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