Author: mick adams
Date: 04:49:12 08/20/98
Go up one level in this thread
On August 19, 1998 at 10:46:59, David Fotland wrote: > >I attended Feng-hsiung Hsu's talk on Deep Blue at Hot Chips 10, and >asked a few questions afterwards. He described the chip and its >performance. > >Here's what he said: > >Search speed is important. He thinks that "Normalized search depth" >needs to be 13 ply to beat Kasparov. He put Hitech at 9 ply, Deep >Thought at 10 ply, Deep Blue prototype at 11 ply. > >But speed alone is not enough to beat GM in a match, since GM will >prepare and learn program's weaknesses. Need to have very few >weaknesses, and only weaknesses that are difficult exploit. > >Chip speed is secondary. Integration level and chess knowledge is >paramount. Encapsulate every chess evaluation term from chess books. >Create terms to deal with every known computer weakness. Put everything This chappie has gotta be the biggest prefabricated pervert in a long time.>on one chip. > >Deep blue had 2 SP2 Frames. Each has 15 SP2 nodes (30 total). >Each node two deep blue boards. Each board has 8 deep blue chips. >200 million chess positions per second average. he estimated that >each chess position was equivalent to about 10,000 instructions >on a general purpose CPU. > >the chip contains: >- move generator >- move stack >- repetition detector >- evaluation function (fast and slow) >- alpha-beta search control >- connected with 19 bit wide move bus > >Evaluation is about 2/3 of the chip area. Move generation is about >3/4 of the rest. > >Move generator is similar to Deep Thought. 8x8 combinational array. >generates a move in 2 clocks. Can generate checking and check evasion >moves (used in quiescent search). > >The fast evaluation is one cycle and includes all the big terms. >The slow evaluation takes 8 to 11 cycles, iterating across the columns >of the chessboard, then combining results. Many small rams are >used in the evaluation. > >The fast evaluation includes material, engame tables and logic for >draw detection, endgame king and pawn race, and piece placement tables. >The piece placement tables take the from square, to square, attacking >piece type, victim piece type, and do table lookup to get a value. >The tables are small. 1024x10 bits indexed by attacking piece and >to square, 512x10 bits indexed by attacking piece and victim piece >for each color. > >The endgame tables are only KP vs K, KR vs KP, KQ vs KP, and >KRP vs KP. > >The slow evaluation scans one column per clock and accumulates >results. It has special logic to figure out development and >pins. It has many small rams for different evaluation terms >(exact number not specified). > >The chip is 0.6 microm CMOS (old technology). >1.5 million transistors, 1 watt, 25 Mhz clock. >2.5 million chess positions per second per chip sustained (10 clocks ave). >Single chip plays at strong grandmaster level. > >480 chip system played against Kasparov, and sustained about >200 million chess positions per second (less than 1/5 full speed). > >He estimated the publicity was worth $2 billion to IBM. > >He thinks state of the art process can give 30 million chess positions >per second in a single chip today. A small array of such chips >plugged into a PC could beat Kasparov. In a few years (0.18u) a single chip >could be as fast as the entire Deep Blue machine. > >He said the key to success is the evaluation function. He tested >against some micro programs using a single chip, slowed down by >5-10X, and beat commercial programs 10-0. He said this was because >of the work they did to avoid typical computer chess weaknesses. > >The opening book has 3 parts: >- grandmaster book designed to get to interesting positions >- autogenerated book from game collection >- in positions where the autogenerated book has low counts and >poor statistics, a random bonus is generated to vary play. > >Hsu is negotiating with IBM for rights to the chip, and plans to >commercialize it. > >David Fotland
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