Deep Blue was an IBM computer that defeated world chess champion Garry Kasparov in 1997. It used specialized chess chips that could evaluate millions of positions per second to search the game tree deeply. Each chip contained a move generator, evaluation function with fast and slow components, and search control logic. After initial losses to Kasparov in 1996, improvements to Deep Blue's evaluation function and search algorithms allowed it to win the rematch in 1997, demonstrating that a computer could defeat the top human player at chess under tournament time controls.

1. IBM’S DEEP BLUE
CHESS
GRANDMASTER CHIPS
DESIGN PHILOSOPHY, GENERAL ARCHITECTURE,
AND PERFORMANCE OF THE CHESS CHIPS

2.  Ujitha Iroshan
 Nadeeshaan Gunasinghe
 Dulanga Sashika
Presenters

3.  Introduction
 History
 Origin of IBM’s Chess Grandmaster
 Task and Design Philosophy
Journey

4.  General Architecture
 Common chess machine Overview
 System Configuration
 Chip Overview
 Move Generator
 Evaluation Function
 Smart Move stack
 Search Control
 Performance
Journey Cont..

5. IBM Deep Blue World chess champion
Garry Kasparov in 1997
What is Deep Blue ?
Vs

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.  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. 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. 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.  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. 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. 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.  Assign numerical values for evaluation
function
■ +1- Computer Player Wins
■ -1- Computer Player Loses
■ 0- Drawn position
Choosing the next move Ctd..

14. Can regular Min-Max search be used in a
Chess Game?
Common chess machine Overview cont..

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.  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.  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. 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.  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. Inside of a chess chip
Chess
Chip
Smart
Move
stack
Evaluation
Function
Search
Move
generator

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. 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. 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. Find Victim and Find Attacker
Move Generator Ctd..

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. 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. Other moves generated by Move generator
 checking moves
 check-evasion moves
 Detect Hung Pieces
 Measures the forcefulness of checks
Move Generator Ctd..

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. Fast Evaluation

30. The piece placement table
computes a position’s incremental
evaluation.
Uses three RAMs.

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. The king-and-pawn array
mainly detects the “pawn can run” condition

33. The Endgame logic and ROMs
Mainly recognizes unusual endgame conditions

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. 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. 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. 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. 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. Thank You

40. Questions?