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Pentium Bugs, Part II

Pentium Bugs, Part II -- Following up on the Pentium division bug reported in TidBITS-253, Intel has confirmed that the math error can occur in single, double, and extended precision divides and potentially impact the precision of results from the 4th to the 19th significant digit. Intel maintains that the bug will not affect most Pentium users, and that, statistically, the bug is not likely to occur in hundreds (or even thousands) of years of normal use. However, engineers, scientists, researchers, and other power users remain concerned about the bug, and reports have circulated in the mainstream media. Intel pledges to work with users of applications involving intensive floating point calculations and, if necessary, replace their chips. In the meantime, intensive discussion of the bug continues to take place in the newsgroup <> and a FAQ is available (in DOS ASCII format) at:

On a related note, a new bug has surfaced in write-back and write-through caches of the 100 MHz version of Intel's Pentium chip (P100). The bug prevents multithreading from functioning at all on operating systems capable of supporting it (Windows NT, OS/2, and Unix, among others). Although it's possible to disable those caches, this results in a 30 percent performance reduction. The bug does not occur on lower-clock speed versions of the Pentium. Intel claims it has fixed the problem and is shipping correct versions of the P100. [GD]

Intel Technical support -- 800/628-8686 (US)
916/365-3551 (International) -- 44 (0) 793 696776 (Europe)
Information from:
InfoWorld -- 28-Nov-94, Vol. 16, #48


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