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IBM’s computer checkmated a human chess champion in a computing tour de force
Close-up shot of two of Deep Blue's processor cabinets in a server room, mid-1960s

In 1997, IBM’s Deep Blue did something that no machine had done before. In May of that year, it became the first computer system to defeat a reigning world chess champion in a match under standard tournament controls. Big Blue’s victory in the six-game marathon against Garry Kasparov marked an inflection point in computing, heralding a future in which supercomputers and artificial intelligence could simulate human thinking.

Deep Blue derived its chess prowess through brute force computing power. It used 32 processors to perform a set of coordinated, high-speed computations in parallel. Deep Blue was able to evaluate 200 million chess positions per second, achieving a processing speed of 11.38 billion floating-point operations per second, or flops. By comparison, IBM’s first supercomputer, Stretch, introduced in 1961, had a processing speed of less than 500 flops.

Deep Blue wasn’t just a breakthrough for the world of chess. Its underlying technology advanced the ability of supercomputers to tackle the complex calculations needed to discover new pharmaceuticals, assess financial risk, uncover patterns in massive databases, and explore the inner workings of human genes.

Deep Blue computing power 32 processors 200 million chess positions evaluated per second 11.38 billion floating point operations per second (flops) of processing speed
Building a digital chess master

Chess has long been considered an ideal test of whether a computer could rival the power of the human brain. It’s a highly complex game that poses formidable computational challenges — there are approximately 1,040 possible legal moves.


IBM engineer and mathematician Alex Bernstein wrote the first complete computer chess program in history, which ran on an IBM 704. It could process 42,000 instructions per second and had a memory of 70 kilobytes.


A program developed at MIT on an IBM 7090 became the first to play regular chess credibly. It could evaluate 1,100 positions per second.


Programs managed to win several amateur chess tournaments, but none could approach the skill of a grandmaster.


That began to change in 1985 when a graduate student at Carnegie Mellon University, Feng-hsiung Hsu, helped develop an advanced chess-playing machine called ChipTest, which would win the North American Computer Chess Championship in 1987. (Hsu would eventually become the author of the book Behind Deep Blue: Building the Computer That Defeated the World Chess Champion.) Murray Campbell, a computer scientist and accomplished chess player himself, began collaborating with Hsu around that time. “I had had a long interest in computer chess and had even written a chess program as an undergraduate,” Campbell would later tell Scientific American. The duo welcomed a number of other colleagues in their quest to create Deep Thought, which became the first program to defeat a grandmaster.

In 1989, both Hsu and Campbell were hired at IBM Research to build a chess computer. They continued their work with the help of other IBM computer scientists, including Joe Hoane, Jerry Brody and C. J. Tan. The chess-playing computer they sought to improve was renamed Deep Blue, a nod to IBM’s nickname, Big Blue.

Challenging Garry Kasparov

The Deep Blue team had an ambitious goal: to develop a computer so powerful that it could beat the world’s best human chess player. Deep Blue’s first major test occurred in February 1996, when it took on reigning champion Garry Kasparov in six games held in Philadelphia. Deep Blue won the first game, which marked the first victory by a computer against a reigning world champion under regular time controls. But Kasparov recovered and won the match 4–2.

The IBM team set to work on improving Deep Blue for a rematch. They improved the databases dealing with chess endgames, created a more powerful evaluation function for chess positions, hired additional chess grandmasters to advise the team, and developed methods to disguise the computer’s strategy. (The upgrades not only enhanced Deep Blue but also led to better training tools for chess players in the years to come. India would go on to produce a significant number of chess stars, mainly due to the wider availability of computerized training resources. Veselin Topalov, the challenger to the World Chess Champion title in 2010, used an IBM Blue Gene/P supercomputer during his preparation for the match.)

With the eyes of the world media upon them, Deep Blue again squared off against Kasparov in May 1997, this time at the Equitable Center in New York. The rematch was widely seen as a symbolic test of whether supercomputers were catching up to human intelligence. Kasparov won the first game. Deep Blue took the next. The following three games were played to a draw. But Deep Blue prevailed in the tension-filled Game 6, thereby achieving a resounding victory, 3.5–2.5, in the rematch and becoming the first computer system to defeat a reigning world champion under standard tournament time controls.

“I have to pay tribute,” Kasparov said grudgingly. “The computer is far stronger than anybody expected.”

Deep Blue prevailed in the tension-filled Game 6, becoming the first computer system to defeat a reigning world champion under standard tournament time controls
Deep Blue’s legacy

After the victory over Kasparov, Deep Blue was retired to the Smithsonian Museum in Washington, D.C. But IBM went on to develop new kinds of massively parallel computers such as Blue Gene and Watson. In 1999, IBM built on its experience with Deep Blue and launched the Deep Computing Institute, with the goal of harnessing advanced computing to solve complex technological and business problems.

Deep Blue has had an impact on computing in many industries. It gave developers insights into ways they could design computers to analyze a vast number of possible solutions to other complex problems. Deep Blue’s architecture has been applied widely in financial modeling, which requires a rapid evaluation of value and risk associated with many stocks and portfolios.

Computer breakthroughs inspired by Deep Blue have likewise been used in data mining to help discover unlikely patterns in large databases, using the tremendous speed and capacity of massively parallel supercomputers. Deep Blue has also made its mark in healthcare, helping the pharmaceutical industry to develop new drugs. Analyzing drug interactions on a molecular level requires massive amounts of processing and computational power, and advanced computers can cut the development time for drugs dramatically and reduce costs.

Although the technology behind Deep Blue has found many other applications, the computer will always be remembered for its historic victory against Kasparov. In terms of chess, Deep Blue was a game-changer — literally. “For the first time in the history of mankind, I saw something similar to an artificial intellect,” Kasparov said. “I know very few chess players who could take this heat.”

Added IBM’s C. J. Tan, “Garry prepared to play against a computer. But we programmed it to play like a grandmaster.”

For the first time in the history of mankind, I saw something similar to an artificial intellect Garry Kasparov Chess grandmaster and World Chess Champion
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