33:
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622:
650:
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643:
616:
949:. For instance, if one Belle computer searches three levels deep, the other might search to four. Thompson concluded that for each additional level of search, Belle improved by approximately 250 rating points. This effect has been replicated in self-play experiments with different machines. Beyond 2,000 points, however, Thompson found that improvements leveled off.
931:
In 1983, Belle competed in the U.S. Open, where it scored 8.5 points in twelve games with a performance rating of 2363. Later that year, the USCF awarded Belle the rank of master. Because it reached this level before any other chess computer, Belle was awarded the $ 5,000 Fredkin prize. Belle's reign
944:
approach to chess computing. In the late 1970s, Thompson became interested in the limits of this method, playing different versions of Belle against one another. Using identical machines allowed him to minimize effects of the individual machine's play style while isolating the effects of
853:
The move generator now included 64 transmitter and receiver circuits. Each transmitter remembered the piece on its square and potential moves that piece could make. Each receiver detected incoming moves, or threats, from other pieces. Extra circuitry detected
840:
These changes reduced the role of the PDP-11 software. Now, the software controlled these three devices and ran the alpha-beta pruning algorithm. The second generation of Belle could search 5,000 positions per second.
932:
ended when it placed sixth in the Fourth World
Computer Chess Championship, despite being the favorite to win. It managed one more win at the ACM Championships in 1986 before retiring.
911:
In 1980, the third generation of Belle won the third World
Computer Chess Championship in Linz, Austria. After four rounds, it had a score of 3.5 in four games, tied with the
760:
Belle represents a move by defining a "from" square and a "to" square, using a ∆xy offset counter. The rook move above has an offset (2,0), while the bishop's is (2,2).
810:
A similar series of steps uses the move generator to test whether the pseudo-legal move is in fact legal. This ensures that the move does not place the moving side in
899:
In 1978, the second generation of Belle competed at the ACM Computer Chess
Championships, winning with a perfect four wins in four games. In a pivotal game against
912:
896:
and the 1973 ACM Computer Chess
Championship. Over the next year, Belle played several UCSF games and finished 3-1 in the 1974 ACM Computer Chess Championship.
547:, which would eventually become Belle. In competition, this early version encouraged Thompson to pursue a brute-force approach when designing Belle's hardware.
879:
The third generation of Belle was controlled by an LSI-11 computer. Depending on the stage of the game, it examined 100,000 to 200,000 moves per second.
427:
795:
This offset is combined with the contents of the "from" register and moved to a 6-bit "to" register. These two registers fully describe a potential
119:
474:
849:
Belle's final incarnation was completed in 1980. It consisted of further improvements to the speed of move generation and evaluation.
555:
Belle's design underwent many changes throughout its lifetime. The initial chess program was rewritten to utilize move-vs-evaluation
78:
875:
Belle's alpha-beta algorithm was now implemented in microcode, controlling the move generator, evaluator, and transposition table.
766:
1202:
946:
803:
1324:
420:
1293:
1274:
42:
89:
543:
operating system, Ken
Thompson turned his attention to computer chess. In summer 1972, he began work on a program for the
94:
471:
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478:
413:
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988:
963:
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781:
464:
214:
923:
in eight moves, winning the game on move 41. During the game, Belle searched 160,000 positions per second.
893:
822:
Belle's second generation was completed in 1978. It implemented several improvements over its predecessor.
84:
109:
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1317:
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159:
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169:
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279:
104:
560:
1352:
1310:
916:
493:
124:
903:, the runner-up, Belle examined 5,000 positions per second, while Chess 4.7 examined 3,500.
940:
Because of its ability to generate and analyze many chess positions, Belle represented the
389:
915:
chess machine. In a tie-breaker for the world-champion title, Belle broke through Chaos's
865:
The evaluator could now examine square control, using 64 specialized circuits, as well as
796:
8:
1258:
973:
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513:
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448:
369:
114:
74:
67:
802:
A test circuit compares the move to the existing board to determine whether the move is
1180:
941:
774:
769:
to be used with software version of Belle on the PDP-11. His design had several steps:
501:
154:
99:
1229:
Heinz, E. A. (2001). "Self-play, deep search and diminishing returns - Ken
Thompson".
1409:
1289:
1270:
1246:
1217:
978:
556:
467:
384:
164:
1208:
Levy, D.; Mittman, B.; Newborn, M. (1980). "3rd World
Computer Chess Championship".
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354:
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194:
269:
259:
830:, which it used to store moves, rather than outputting them to software.
523:. The overall architecture of Belle was used for the initial designs of
859:
827:
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for move generation, four custom boards for position evaluation, and a
339:
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204:
485:
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983:
920:
497:
456:
394:
379:
324:
299:
284:
254:
32:
855:
524:
505:
489:
481:. It was the first system to win using specialized chess hardware.
199:
806:. If it is, the "from" and "to" registers are output to software.
149:
1442:
1302:
544:
349:
304:
264:
234:
219:
892:
Ken
Thompson's software version of Belle competed in the 1972
833:
A hardware implementation of the position evaluator was added.
1458:
364:
1404:
1347:
540:
49:
784:
provides a bit-code for the move offset, e.g. (2,2) for a
492:
to coordinate its chess hardware. There were three custom
1195:
Condon, J.H. and K. Thompson, "Belle Chess
Hardware", In
1286:
Kasparov versus Deep Blue: computer chess comes of age
836:
A hardware implementation of the transposition memory.
1265:(1983). "Chapter 9: Belle". In Frey, Peter W. (ed.).
1122:
1120:
519:At the end of its career, Belle was donated to the
1207:
1117:
1047:
1045:
780:Once a friendly piece is found, a ∆xy move-offset
989:Pawnless chess endgame § Browne versus BELLE
1471:
576:
1269:. New York: Springer-Verlag. pp. 201–210.
1042:
872:The transposition memory was increased to 1 Mb.
459:. In 1983, it was the first machine to achieve
1257:
1175:
567:to avoid redundant examinations of positions.
1318:
421:
765:In 1976, Joe Condon implemented a hardware
1325:
1311:
1026:
1024:
1022:
570:
475:North American Computer Chess Championship
428:
414:
1199:(ed. M.R.B.Clarke), Pergamon Press, 1982.
628:
484:In its final incarnation, Belle used an
1283:
1019:
935:
777:searches the board for friendly pieces.
635:
621:
559:and evaluate positions by prioritizing
1472:
649:
1306:
1228:
906:
887:
656:
642:
612:
90:Efficiently updatable neural networks
19:This article is part of the series on
817:
844:
13:
969:Ken Thompson (computer programmer)
14:
1501:
479:World Computer Chess Championship
1332:
964:Glossary of computer chess terms
926:
655:
648:
641:
634:
627:
620:
614:
95:Handcrafted evaluation functions
31:
1156:
1147:
1138:
1129:
1108:
1099:
1090:
826:The move generator had its own
1267:Chess Skill in Man and Machine
1081:
1072:
1063:
1054:
1033:
1010:
1001:
1:
1169:
1197:Advances in Computer Chess 3
894:U.S. Open Chess Championship
504:. The computer also had one
7:
952:
110:Stochastic gradient descent
10:
1506:
539:Following his work on the
534:
160:Principal variation search
1451:
1430:
1387:
1366:
1340:
1284:Newborn, Monroe. (1997).
1210:Communications of the ACM
882:
550:
994:
477:five times and the 1980
1490:One-of-a-kind computers
1431:Associated institutions
1203:Computer History Museum
919:and went on to declare
571:Hardware move generator
521:Smithsonian Institution
170:Monte Carlo tree search
1288:. New York: Springer.
1243:10.3233/ICG-2001-24205
447:that was developed by
280:Dragon by Komodo Chess
105:Reinforcement learning
1367:Programming languages
1353:Plan 9 from Bell Labs
1181:"Ken, Unix and Games"
125:Unsupervised learning
43:Board representations
1162:Newborn 1997 p. 123.
1135:Newborn 1997 p. 122.
1007:Newborn 1997 p. 147.
936:Performance analysis
563:. Belle also used a
527:, the progenitor of
514:transposition tables
470:of 2250. It won the
75:Deep neural networks
68:Evaluation functions
1126:Newborn 1997 p. 92.
1096:Newborn 1997 p. 98.
1087:Newborn 1997 p. 93.
1016:Newborn 1997 p. 91.
974:Joseph Henry Condon
565:transposition table
115:Supervised learning
100:Piece-square tables
917:Alekhine's Defense
907:World Championship
888:Early competitions
561:material advantage
502:alpha-beta pruning
500:implementation of
155:Alpha-beta pruning
1467:
1466:
1341:Operating systems
1295:978-0-387-94820-1
1276:978-0-387-90815-1
1259:Condon, Joseph H.
1153:Heinz 2001 p. 76.
1144:Frey 1983 p. 209.
1114:Levy 1980 p. 664.
1105:Levy 1980 p. 663.
1078:Frey 1983 p. 207.
1069:Frey 1983 p. 206.
1060:Frey 1983 p. 205.
1051:Frey 1983 p. 204.
1039:Frey 1983 p. 203.
1030:Frey 1983 p. 202.
979:Endgame tablebase
818:Second generation
754:
753:
557:quiescence search
438:
437:
165:Quiescence search
144:search algorithms
25:Chess programming
1497:
1485:History of chess
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845:Third generation
757:Defining a move.
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658:
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637:
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630:
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488:general-purpose
430:
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335:Leela Chess Zero
35:
16:
15:
1505:
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1500:
1499:
1498:
1496:
1495:
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1480:Chess computers
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1296:
1277:
1216:(11): 661–664.
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788:or (2,0) for a
773:A 6-bit "from"
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762:
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451:(hardware) and
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183:Chess computers
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1422:Thompson shell
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1177:Dennis Ritchie
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959:Computer chess
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867:pawn structure
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767:move generator
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455:(software) at
445:chess computer
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1263:Thompson, Ken
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1179:(June 2001).
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927:Master rating
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529:IBM Deep Blue
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463:play, with a
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248:Chess engines
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26:
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18:
17:
1416:Space Travel
1414:
1394:
1334:Ken Thompson
1285:
1266:
1237:(2): 75–79.
1234:
1231:ICGA Journal
1230:
1213:
1209:
1196:
1188:
1185:ICGA Journal
1184:
1158:
1149:
1140:
1131:
1110:
1101:
1092:
1083:
1074:
1065:
1056:
1035:
1012:
1003:
947:search depth
939:
930:
910:
898:
891:
878:
848:
839:
821:
809:
804:pseudo-legal
764:
756:
554:
538:
518:
512:for storing
483:
461:master-level
453:Ken Thompson
440:
439:
215:Deep Thought
195:ChessMachine
189:
120:Texel tuning
79:Transformers
942:brute-force
270:CuckooChess
260:Chess Tiger
1474:Categories
1170:References
860:en passant
449:Joe Condon
340:MChess Pro
275:Deep Fritz
205:Cray Blitz
1438:Bell Labs
1251:1389-6911
1222:0001-0782
984:Bell Labs
921:checkmate
901:Chess 4.7
498:microcode
457:Bell Labs
395:Turochamp
385:Stockfish
380:SmarThink
325:KnightCap
300:GNU Chess
285:Fairy-Max
255:AlphaZero
210:Deep Blue
85:Attention
55:Bitboards
1388:Software
953:See also
856:castling
775:register
525:ChipTest
506:megabyte
490:computer
370:Shredder
230:Mephisto
200:ChipTest
1358:Inferno
782:counter
535:Origins
345:Mittens
310:Houdini
150:Minimax
1443:Google
1292:
1273:
1249:
1220:
883:Career
786:bishop
551:Design
545:PDP-11
510:memory
494:boards
486:LSI-11
468:rating
350:MuZero
330:Komodo
320:Junior
315:Ikarus
305:HIARCS
265:Crafty
235:Saitek
220:HiTech
1459:UTF-8
1452:Other
1395:Belle
995:Notes
913:Chaos
828:stack
812:check
443:is a
441:Belle
400:Zappa
390:Torch
375:Sjeng
365:Rybka
360:REBEL
295:Fruit
290:Fritz
225:Hydra
190:Belle
138:Graph
1405:grep
1348:Unix
1290:ISBN
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1191:(2).
858:and
797:move
790:rook
541:Unix
465:USCF
355:Naum
142:tree
140:and
50:0x88
1410:sam
1239:doi
508:of
472:ACM
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1379:Go
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