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Deep Blue Branching Out

IBM fine-tunes Deep Blue for commercial arena

By Gail Robinson, EE Times

Yorktown Heights, N.Y. -- Now that the much ballyhooed chess match between IBM's Deep Blue and Garry Kasparov is history, the technology responsible for the outcome is being retargeted toward new and very different applications.

The IBM researchers who developed the custom chip at the heart of the system--along with their counterparts at VLSI Technology Inc. (San Jose, Calif.), which handled the implementation and manufacturing of the technology--are examining its potential for financial modeling, pharmaceutical and medical applications. Such fields might value the system's ability to search huge data sets intelligently.

"The publicity of the match might cause people to lose sight of the practical issues," said Tom Ebzery, director of VLSI's Eastern Region Technology Center (Burlington, Mass.)."IBM was not just in this for the fun of it." While the project garnered huge worldwide exposure for Deep Blue in particular and for parallel processing in general, IBM's objective was to learn more about applying the technology to real-world problems, Ebzery said. "Playing chess is a nicely definable parallel-processing application, but the whole idea is how can you then use it in other applications that are more lucrative," he said.

Potential areas under investigation match similar operations in which goal-directed searches of huge combinatorial databases are needed. For example, drug design could be a potential market because huge numbers of molecular configurations must be tested before a new drug is identified. Another area is financial modeling. "The investment community will eat all the Mips that you can throw at them just doing economic analysis," said a spokesman for VLSI.

The investment community is evaluating one example: an investor-oriented model of the mini SP2, a smaller version of Deep Blue. The system uses a variation of the chess-playing concept of anticipating outcomes three or four moves ahead.

Deep Blue blends special-purpose hardware and general-purpose supercomputing. The parallel processor was structured as 32 workstation-class machines, connected to 16 VLSI custom chips. "These custom chips were designed to specifically handle chess computations. They have the capability of generating chess moves by themselves," said F.H. Hsu, a research staff member at IBM's T.J. Watson Research Center. The chips could also evaluate chess positions based on database searches of model games.

Essentially, each chip was a complete chess machine in itself, evaluating 2 million to 3 million chess positions per second. "If you compare that to a chess program run on a Cray computer, each chip is roughly about the same speed as the fastest Cray," noted Hsu. The design had to break new ground in memory integration on chip as well as in coordinating memory and processors at the system level.

The Deep Blue project required a high level of integration--about 2 million transistors per chip--which was actually beyond the technology's capability when the project was conceived in the early 1990s. "There were 512 chips used in the full-up system--where each chip consisted of 1.7 million transistors, breaking down to about 150,000 gates and about 300,000 bits of RAM and ROM," Hsu recalled. Overall, the chess-evaluation process makes high demands on the memory-to-processor bottleneck, and the design team needed a lot of flexibility when integrating memory and logic on chip. IBM used VLSI's memory-compiler technology, which could target different-sized memories to meet design requirements.

"The compiler would automatically generate those configurations per their specification--a capability that VLSI brought to the table back in the early '90s," Hsu said.

The hardware provided plenty of processing capability. "A lot of dedicated hardware to do the chess specific calculations, data searches and what-if decisions," said Ebzery. "If this had been done in software--an approach taken by some other systems--it would never have had anywhere near the performance that a dedicated hardware engine provides." The speedup resulted in a two orders of magnitude difference for position analysis.

Because of the chip's size, one of the biggest challenges was its layout. "There were about 65 separate blocks of memory that had to be wired together, so it was a very complex physical design problem that also had to meet the performance goals," noted Ebzery. "So, we had to work closely with the IBM engineers and understand where their critical timing paths were to get through the back end of the process."

While the chips were optimized for the basic search and evaluation operation, an important innovation at the system level was the integration of expert knowledge--in this case, chess experts--that would sort through the raw position look-ahead information to decide on the best move. "You can do searches that are quite different from what you are limited to in hardware," Hsu said. The dedicated hardware algorithm could look up to eight moves ahead, covering all possibilities, which turns out to be a huge combinatorial search problem.

"At the software level, you can do more selective searches. The idea is that you can go much deeper than normal, based on intelligent evaluation of the situation," Hsu said.

The software was written in C and runs on AIX, an IBM version of Unix. Some extensions were added to map the chip data-search results directly into the memory space."To be able to solve a part of the search at the system level gives you flexibility," he said. "If you want to do a certain depth of search, the operation can be adjusted on how much information you have at the moment."

Hsu called the scheme pretty sound and said the team may further optimize the software in a future system. "In the end, it was software innovations and built-in chess-expert knowledge that tipped the scales," he said. In looking at the difference between match one and match two, the amount of chess knowledge in the program was critical." The improvements resulted from a detailed analysis of why the machine didn't play certain positions well. One specific performance improvement simply involved reducing memory delays by knowing what information to request.

The two groups are now looking at the hardware/software interface as a means of getting better performance for the system. The position evaluation and look-ahead chips interface directly with external RAM, which opens up the possibility of bringing software flexibility down to the hardware level, Hsu said.

The chips could also be enhanced. "There is a lot of room to move down the process-technology road map to achieve better performance and higher clock rates," noted Ebzery. "And there's certainly a lot of opportunity to add more functionality. So we are poised and ready to support IBM if and when they decide to schedule another match and build another machine."

(Next article.)


(c) 1997 CMP Media, Inc

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