Deep Blue Architecture Murthy Ganapathibhotla
Agenda • Introduction • Overview of Deep Blue Architecture • Conclusion
INTRODUCTION • What is Deep Blue ? • What is a Chess Computer ? • How are Moves Computed ? • History of Deep Blue.
Introduction What is Deep Blue ? Deep Blue was IBM’s Chess Playing Computer. It was the First Computer System to win Against the world chess champion Garry Kasparov.
Introduction What is a Chess Computer ?
Introduction What is a Chess Computer ? A Computer that plays Chess !
Introduction What does a chess computer have to do in order to defeat the world champion !
Introduction If we take a closer look at the way chess is played… Each player has 16 pieces of chess coins to play with and 20 possible moves.
Introduction • Lets say White begins the game. It has 20 possible moves. The same options are there even for a Black player. 20 possible moves.
Introduction Total Number of Moves For White = 20 Moves for Pawns = 8 + 8 = 16 ( one step) ( 2 steps) Moves for Knights = 2 + 2 = 4 Total = 20
Introduction Level 1 : 20 possible moves for white. Level 2 : 20 * 20 = 400 possible moves for black, depending on what white does. Level 3 : 400 * 20 = 8,000 for white. Level 4 : 8,000 * 20 = 160,000 for black…... For all possible Chess Board Positions You need to Evaluate 10 ^ 120 possible moves!
Introduction What will a Chess Computer do ? • Evaluates 5 or 10 or 20 moves ahead in advance. • The depth of the tree it can generate depends on the speed of the computer • Once it generates the tree it needs to evaluate the positions using some evaluation function .
Introduction So The Faster Your Computer generates the Moves, The Better would be the Performance !
History Of Deep Blue • Started as “Chip Test” at Carneige Mellon University by Feng-Hsiung Hsu. Then It Became “Deep Thought” And Finally “Deep Blue”.
Deep Blue Architecture • Overview • Chess Chip • Chess Chip Evaluation Functions • RS /6000 Processor • Software Issues
Overview • Based on IBM RS/6000 SP Super Computer. • Contains 30 IBM RS/6000 Processors connected through a high speed switching network. • Each processor in the system controls upto 16 chess chips • So, Deep Blue had 480 chess chips !
Chess Chip • Move Generator : Generates next possible move. • Position Evaluator : Evaluates a leaf position. • Single Move : Takes 40,000 General purpose instructions At 2 to 2.5 million chess positions per second , one chess chip is equivalent to 100 billion instructions per second Super Computer !
Chess Chip Evaluation Functions • Piece Placement Evaluation Each piece on Every Square • End Game Evaluation Counts of Various Pieces on the Chess board. • Slow Evaluation It computes various concepts such as King safety…
RS / 6000 Processor • Stands for RISC System / 6000 • Belongs to the S family -- IBM Symmetric Multiprocessor Family • Supports 32 bit and 64 bit applications. • Gives High End Commercial Performance.
Rack Packaging 2 Enclosures : • Central Electronics Complex - Processor Cards - Memory Controller - Memory Cards - Power Supplies and Cooling Systems. • A Rack for 4 I/O drawers - One for primary SCSI drawer and room for other I/O expansion.
Processor Card • 6 Processors per card. • Runs at 455 MHz. • Separate 128 KB internal L1 Cache for instructions and data. • L2 Cache Controller and 4 way set associative 8 MB L2. • 5 Pipeline Execution Units : Branch, Load/Store, Fixed Point, Complex Fixed Point and Floating Point.
System Bus • System bus uses 128 bit data path and Separate 64 bit address path • Address, Data , Control Parity Checked • Operates in true Split Transaction mode
Memory • Base Configuration includes 2 GB SD RAM. • Max Configuration is 64 GB. • Accommodates up to 16 Memory Cards • Memory Cards are used in Sets of four called Quads. • SDRAM cards directly attached to the memory cards.
Remote I/O Connections • The I/O Subsystem is connected to the RIO Chip Interface by means of System buses. • Four RI/O connections are connected to a single Hub chip. • Offers Buffering as well !
I/O Drawer • Cooling effect is provided by means of Fans. • Primary I/O Drawer Contains 12 hot plug DASD bays, one available media bay, one floppy disk drive, one CD ROM, One mouse port, two serial ports and a parallel port. The I/O sub system is expandable By attaching 4 I/O Drawers to a single CEC.
Operating System • IBM AIX Operating System. • Uses Message Passing method of parallelization. • Whole program code is written in C ! • Algorithm used is the minimum window alpha-beta search algorithm.
Search Strategy • Search through all possible moves Until you find the best possible move ! • Make sure that when you lose a piece, you lose it optimally, i.e. let the penalty be just adequate without hurting much.
What Deep Blue did ? • Searched 40 billion positions for each move ! • Search was distributed among • IBM RS/6000 Network • Micro channel bus inside workstation node.
Brief Description • Take for example, A 12 ply search ( ply = Move) • The master node among the 30 nodes will evaluate the first four plies in software. Now , number of positions increases about a 1000 times.
Brief Description • All the 30 processors (including master) Will evaluate the next four plies in software. Now the number of positions increases about a 1000 times • Now the remaining 4 plies are taken care by the Chess Chips.
Brief Description • Therefore, Software is responsible for 1 % of the moves And evaluating 2/3rd the depth of the tree.
“ Behind every Great Innovation, there is a meticulous human brain ”.
Murray Campbell Feng-hsiung Hsu
Kasporov vs Deep Blue Match The various moves of this match can be watched at this web site http://www.research.ibm.com/deepblue/watch/html/c.shtml
A Philosophical Statement • Deep Blue entirely used Brute Force approach --- Can It Match the thinking process of a Human Brain ? • During the match, it seems the engineers have given Human input ! • So , shall we wait for a Re Match ?
Final Word • Lets see whether the honor of the human race will be defended during a rematch in the future !
References • Wikipedia http://en.wikipedia.org/wiki/Deep_Blue How Stuff Works http://computer.howstuffworks.com/chess2.htm • The RS/6000 Enterprise Server Model S80 Technology and Architecture (Technical White paper from IBM) • http://www.cs.berkeley.edu/~sergiu/cs267/assignament0/ • IBM Research http://www.research.ibm.com/deepblue/