The Flaw in the Intel Pentium Chip

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In late 1994, the media began to report that there was a flaw in the new Pentium microprocessor produced by Intel. A flaw in the Pentium was especially significant since at that time it was the microprocessor used in 80% of the personal computers produced worldwide. Apparently, flaws in a complicated integrated circuit such as the Pentium are not uncommon. Most of these flaws cannot be detected by the user and do not affect the operation of the computer. The flaw that was discovered in 1994 was different. It caused incorrect answers when performing double-precision arithmetic, a very common computer operation. The flaw was easily detected by computer users. In fact, it first came to light when a university researcher noticed that the results of some calculations he was performing using his PC were incorrect. Many daily newspapers across the country carried stories about this problem.

Intel’s initial response was that although there was indeed a defect in the chip, the defect was insignificant and the vast majority of users would never even notice it. The chip would be replaced for free only for users who could demonstrate that they needed an unflawed version. Of course, this approach did not satisfy most Pentium owners since no one can predict whether the flaw might be significant in a future application. IBM, a major Pentium user, canceled the sales of all IBM computers containing the flawed chip. Finally, after much negative publicity in the popular personal computer literature and the daily press, and an outcry from Pentium users, Intel agreed to replace the flawed microprocessor with an unflawed version for any customer who asked to have it replaced.

It should be noted that long before news of the flaw surfaced in the press, Intel was aware of the problem and had already corrected it on subsequent versions. They