Ibm's deep blue chess grandmaster chips


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This includes the architecture, design philosophy and the internal structure of the IBM chess grandmaster chips, Intelligent chess machine which was capable of defeating the world chess champion Garry Kasparov in 1997

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Ibm's deep blue chess grandmaster chips

  2. 2.  Ujitha Iroshan  Nadeeshaan Gunasinghe  Dulanga Sashika Presenters
  3. 3.  Introduction  History  Origin of IBM’s Chess Grandmaster  Task and Design Philosophy Journey
  4. 4.  General Architecture  Common chess machine Overview  System Configuration  Chip Overview  Move Generator  Evaluation Function  Smart Move stack  Search Control  Performance Journey Cont..
  5. 5. IBM Deep Blue World chess champion Garry Kasparov in 1997 What is Deep Blue ? Vs
  6. 6. Creating the first world champion class chess computer is one of the oldest challenge in computer science.  Blitz chip won against grand master in shortened time chess game in 1977  Cray Blitz computer is defeated by International master David Levy in shortened time chess game in 1984 History
  7. 7.  PC programmed in Blitz won against 2nd rank chess player in 1988 under faster time controls.  Deep blue early version(Deep thought) was defeated by the Champion Garry Kasparov in 1996 under regular time control.  Finally in 1997 Deep Blue won against the World Champion Garry Kasparov under regular time control History Ctd...
  8. 8. Winning a match against the human World chess champion under regulation time control The game had to play out no faster than three minutes per move Task description of Deep Blue
  9. 9. Regular time control  Standard chess tournament time control Faster time control (Shortened time)  Limited time for entire match and for the each moves Task Description Ctd...
  10. 10.  Integrate level  Integrate the maximally possible amount of software-modifiable chess knowledge on to the chess chip.  Computational Speed  Assign weights to positional features Design Philosophy
  11. 11. Common chess machine Overview  Follows the design outlined by Claud Shanon in 1949  Chess 4.5 is the earliest and the first successful chess machine design  Today Chess Machines in one way or another way, are the grandchildren of this Chess 4.5 General Architecture
  12. 12. Choosing the next move  Shannon’s basic design uses a min-max tree  The evaluation function is designed from the computer player’s viewpoint Common chess machine Overview Ctd...
  13. 13.  Assign numerical values for evaluation function ■ +1- Computer Player Wins ■ -1- Computer Player Loses ■ 0- Drawn position Choosing the next move Ctd..
  14. 14. Can regular Min-Max search be used in a Chess Game? Common chess machine Overview cont..
  15. 15.  New developments in Chess 4.5  A hardware move generator  Quiescence search (Capture Search) and Alpha beta Pruning algorithm Common chess machine Overview cont..
  16. 16.  1997 version of DB included 480 chess chips  each chess chip could search 2 to 2.5 million chess positions/s  More software work could increase the speed. But applied software work in chess knowledge area System Configuration
  17. 17.  Search goes parallelly in two levels  One over IBM RS/6000 SP switching network  The other over Micro Channel bus inside a workstation node  Partitioning the search provided a great deal of design flexibility and increased the search speed  SW handled a 1% of the search, but the ⅔ search depth was reduced by SW System Configuration
  18. 18. Block diagram of the Chess Chip Chip Overview The chip’s cycle time lies between 40 and 50 nanoseconds in a 0.6-micron, three- metal layer, 5-V CMOS process. The average number of cycles per position searched is about 10; power dissipation is about one watt
  19. 19.  Each chess Chip works as a chess machine  Why Chess chips rather than software algorithm for the competing?  Provided design possibilities unacceptable by SW  Time-scaling factor dropped from instruction cycle time to gate delay  Only thing required was reexamine of the time complexity of the competing algorithm Chip Overview
  20. 20. Inside of a chess chip Chess Chip Smart Move stack Evaluation Function Search Move generator
  21. 21.  What is move generator?  Used to decide the next best move of a chess piece  An 8x8 array of combinational logic  Move generation is controlled by a hardwired finite state machine Move Generator
  22. 22. Why Deep Blue’s move generator special?  Generate check and check evasion Moves  Generates attacking moves  Hardware pruning of irrelevant chess moves Move Generator Ctd..
  23. 23. A chip cell The combinational logic array is a silicon chess board Each has four major components  Find victim transmitter  Find Attacker Transmitter  Receiver  Distributed arbiter  Four-bit piece register Move Generator Ctd..
  24. 24. Find Victim and Find Attacker Move Generator Ctd..
  25. 25. As described earlier, move generator computes all the moves implicitly for a single move. What if SW is used for this task?... Move Generator Ctd..
  26. 26. Generating moves from a partially generated position  Need to mask the already searched moves  Belle design used 2-bit disable-stack for masking  What is used in Deep Blue? Move Generator Ctd..
  27. 27. Other moves generated by Move generator  checking moves  check-evasion moves  Detect Hung Pieces  Measures the forcefulness of checks Move Generator Ctd..
  28. 28. Evaluation Function What is Evaluation Function?  Evaluation function is a function used by game- playing programs to estimate the value or goodness of a position in the minimax and related algorithms. Evaluation Function of “Deep Blue”  Contain about 66,000 gates not including RAMs and ROMs.  All sub blocks of the evaluation function divided into two sections • Lower sub blocks provide fast evaluation • Upper sub blocks provide slow evaluation
  29. 29. Fast Evaluation
  30. 30. The piece placement table computes a position’s incremental evaluation. Uses three RAMs.
  31. 31. The Game Phase Control  Contains a piece count register  Maintain an XORed piece-location register  The piece-count register addresses game phase control RAMs  The game phase control RAMs produce several control values  simply a bonus or penalty to be added to the evaluation based on the material left on the board.  The most important game phase control value is the king safety relevance  tells the chess chip how to adjust the penalty for bad pawn structure and the bonus for passed pawns
  32. 32. The king-and-pawn array mainly detects the “pawn can run” condition
  33. 33. The Endgame logic and ROMs Mainly recognizes unusual endgame conditions
  34. 34. This is the single most complicated element on the chip, occupying close to half of the chip core. Slow evaluation has a three-stage pipeline  8 X 1 systolic array  40-plus synchronous RAMs  adder tree Computes values for chess concepts such as,  square control, pins, x-rays, king safety, pawn structure, passed pawns, ray control, outposts, pawn majority, rook on the 7th, blockade, restraint and etc. Slow evaluation
  35. 35. This doesn’t exist in the chess chip’s older release. Repetition detector  Contains a 32-entry circular buffer of the last 32 plies of moves.  Use hardware content addressable memory algorithm  Does this detects just simple repetition?  Time complexity is O(n) Smart move stack
  36. 36. implements a minimum-window alpha-beta search algorithm This search can only tell us whether the position searched is better or worse than a single test value. Efficiency- wise, minimum-window-based search seems about the same as the regular alpha-beta search Search Control
  37. 37. In early 1997, used a single chip running at 70% clock speed A hardware bug reduced the chip to 7% to 14% of its regular speed Deep Blue Jr. against the commercial chess programs played 40 games and chess chip score 95% against PC program Performance
  38. 38. The 1997 version of Deep Blue only played six games Deep blue won the match by the score of 3.5 to 2.5 Kasparov is rated around 2815, which placed Deep Blue’s performance at about 2875
  39. 39. Thank You
  40. 40. Questions?
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