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PENTIUM
BUG
The way
Intel handled their mistake
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In mid '94 Intel (and independant parties) found a
floating point bug in their processor. While it is not
unusual for Hardware
bugs in processors it is rare that they are this serious,
furthermore Intel went out of their way to hide the bug. It
was about 6 months later that Intel finally went public with
the bug (1). Even then Intel did not
valuntarily go public with the bug, it was because other
people were discovering it and a thread started on the
internet.
Dr. Thomas Nicely was the first guy to publicly discover
the bug, and he contacted Intel Tech Support regarding this
bug on Monday 24 October (call reference number 51270). But
he was soon silenced by Intel with an NDA as Intel tried to
bury the problem. (2) The bug was found on
many different pentiums including the 60, 66, 75 and 90 mhz
pentium chips, and effected millions of users.
After some cajoling Intel admitted that the bug existed -
but they told people that only professionals that could
prove they needed the bug fixed would get their processors
replaced (3). Users had to prove to intel
that they needed the fixed chip to get it replaced. Intel
minimized the bug by distorting how serious it was to many
people telling people "It only happens to calculations at
the 8th place" or that it was only an issue to researchers
and scientists.
Here are some samples that look a lot more serious than
the 8th or 9th place -
- 5505001/294911 = 18.66600093 (pentium)
- 5505001/294911 = 18.666651973 (powerpc)
- Notice - the 4th decimal
place.
-
- X = 5505001
- Y = 294911
- Z = (X/Y)*Y - X
- --------------
- Expected: 0
- Computed with a pentium with
the bug: -256.00000
-
- X = 4195835
- Y = 2.9999991
- Z = (X/Y)*Y - X
- --------------
- Expected: 0
- Computed with a pentium with
the bug: -192.00000
Intel also implied that the bug only effected FDIV
(floating point division), but it was later proved that many
functions used the FDIV tables and could also be effected. A
few transidental functions effected included the following;
FPTAN, FPATAN, FYL2X, FYL2XP1, FSIN, FCOS, FSINCOS.
(floating point tangent, sins, cosines, exponents).
After some class action law suits got started, and
negative publicity was spinning out of control, Intel agreed
to replace faulty chips unconditionally.
Even the resolution cost PC users lots of money (4).
How would you like to find out that your machine cost you
$300 more than you expected, not to mention thousands or
millions in liabilty because of faulty calculations? That
was a reality that most early pentium users faced.
The issue was never as much the bug itself. The bug was
critical to many users, and converted many users computers
from a cost saving device into a liability. The bigger issue
was that Intel handled the situation very poorly, by first
hiding the facts, then trying to minimize them, and not
owning up to their responsibility and requiring users to
prove to Intel that they needed replacement. (5)
There are also still many pentium computers out there that
users never got around to replace. So next time you see an
"Intel Inside" sticker, you might want to think of it as a
warning label.
For more fun try - HumorPentium
Bug Humor
SUPPORTING ARTICLES
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(1) "Some Scientists Are Angry Over
Flaw in Pentium Chip, and Intel's Response" ~ Wall
Street Journal (11/25/94) P. B4; Clark, Don
- Some scientists are angry about a flaw that Intel
revealed in its Pentium chip that could make computers
answer incorrectly in certain rare instances. The
defect, which is in millions of microprocessors,
involves division problems with the floating-point
processor. The problem was discovered early last
summer [1994], the company says, and the
production processes were changed accordingly. An
Intel spokesman says, "The chip is fine.
Statistically, the average person might see this
problem once in every 27,000 years." But
mathematicians working in precise fields such as chaos
theory take the flaw very seriously. Researcher Dave
Bell says, "There are a lot of people who do research
and have to stand up and publish their results based
on computer simulations. Maybe one of the questions
now will be, was it done on a chip with the bug or
without the bug?"
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(2) Response from Dr. Nicely
- FROM: Dr. Thomas R. Nicely, Professor of
Mathematics, Lynchburg
- College, Lynchburg, Virginia
([email protected])
- TO: Whom It May Concern
- RE: Pentium FPU
- DATE: 16 November 1994
-
- This is in response to the many e-mail inquiries I
have recently received. I have entered into a
temporary nondisclosure agreement with Intel
Corporation, and am therefore not at liberty to
comment further on the Pentium CPU and FPU.
- Information regarding the Pentium CPU and FPU may
be obtained by calling Intel directly at 800-628-8686,
or by contacting Intel representative John Thompson at
408-765-1279.
-
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(3) "A Flaw Chips Away at Intel's Shiny
Image" ~ Washington Post (12/02/94) P. A1; Corcoran,
Elizabeth
- Intel has lost some of its reputation with the
revelation that its Pentium chip is flawed. Not only
has Intel's reputation for quality been compromised,
but analysts say its handling of the situation has
been very poor. Intel CEO Andrew Grove has issued an
apology over the Internet, but the company says a mass
recall is unnecessary because the flaw becomes
apparent with only the most complex calculations.
Intel will sell its existing inventory of flawed chips
until it runs out sometime next year. The company has
reserved the right to decide if a customer needs a
replacement chip.
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(4) "The Real Cost" ~ InformationWeek
(01/09/95) No. 509, P. 12; Gillooly, Brian
- Intel's decision to provide Pentium replacements
to all customers upon request may end up costing large
companies thousands of dollars. Although Intel
replaces the chip for free, companies must handle
reconfiguration, testing, customer downtime, and
equipment depreciation. Analyst Carter Lusher says
replacing Pentiums may cost companies an average of
$289 per system, including administrative, labor, and
downtime costs. Smith Barney in New York will have to
replace Pentiums in 600 PCs, which could cost the
company over $200,000. Analyst Liz Buyer says, "A
charge of $200,000 would certainly turn some heads.
-
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(5) "A Flaw Chips Away at Intel's Shiny
Image" ~ Washington Post (12/02/94) P. A1; Corcoran,
Elizabeth
- Intel has lost some of its reputation with the
revelation that its Pentium chip is flawed. Not only
has Intel's reputation for quality been compromised,
but analysts say its handling of the situation has
been very poor. Intel CEO Andrew Grove has issued an
apology over the Internet, but the company says a mass
recall is unnecessary because the flaw becomes
apparent with only the most complex calculations.
Intel will sell its existing inventory of flawed chips
until it runs out sometime next year. The company has
reserved the right to decide if a customer needs a
replacement chip. Analyst Drew Peck says, "Clearly
[the problem] was grossly mishandled from a
public relations standpoint. Analyst Erik Jansen says,
"I can't believe that Intel is trying to tell a
customer we will decide what makes you happy. They've
successfully created awareness of Pentium. Now Pentium
means watch out."
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