FDIV bug in Pentium chips!!!
Stuart Priest
priest at yorvic.york.ac.uk
Thu Dec 8 07:07:15 EST 1994
In article <3bo1qf$3j2 at news.iastate.edu>, kurtg at iastate.edu (Kurt R Glaesemann) writes:
|> In article <3bl9af$jlp at xap.xyplex.com>, <dlaskey at xyplex.com> wrote:
|> >By the way...If you do any serious number crunching and use 256 in your
|> >calculations such as cell A1 (4195835 * 256)
|> > cell A2 (3145727 / 256)
|> > cell A3 =a1/a2
|> >You are boned. The Pentium will give the result 87407.92362
|> >Acual answer is 87413.2569
|> >
|> >Hmmmmmm The error is to the LEFT of the decimal point. These Chips Suck!
|>
|> You really didn't need more than three significant figures ;-)
|>
|> >Have fun doing taxes...remember calculations done on a Pentium are still your
|> >responsibility. You will be liable for all interest and penalties!
|>
|> I wonder if water comes out linear using quantum mechanics programs on
|> pentiums. :-(
|>
|>
|> --
|> kurtg at iastate.edu
(For those of you not up on the latest.... a bug was found in the
Pentium's math coprocessor a week ago. Intel acknowledged that it knew
about it for a long time.)
Q&A: THE PENTIUM FDIV BUG
Q: How many Pentium designers does it take to screw in a light bulb?
A: 1.99904274017, but that's close enough for non-technical people.
Q: What do you get when you cross a Pentium PC with a research grant?
A: A mad scientist.
Q: What's another name for the "Intel Inside" sticker they put on
Pentiums?
A: The warning label.
Q: What do you call a series of FDIV instructions on a Pentium?
A: Successive approximations.
Q: Complete the following word analogy: Add is to Subtract as Multiply
is to:
1) Divide
2) ROUND
3) RANDOM
4) On a Pentium, all of the above
A: Number 4.
Q: What algorithm did Intel use in the Pentium's floating point divider?
A: "Life is like a box of chocolates." (Source: F. Gump of Intel)
Q: Why didn't Intel call the Pentium the 586?
A: Because they added 486 and 100 on the first Pentium and got
585.999983605.
Q: According to Intel, the Pentium conforms to the IEEE standards 754
and 854 for floating point arithmetic. If you fly in aircraft
designed using a Pentium, what is the correct pronunciation of "IEEE"?
A: Aaaaaaaiiiiiiiiieeeeeeeeeeeee!
TOP TEN NEW INTEL SLOGANS FOR THE PENTIUM
- --------------------------------------------------------------------------
9.9999973251 It's a FLAW, Dammit, not a Bug
8.9999163362 It's Close Enough, We Say So
7.9999414610 Nearly 300 Correct Opcodes
6.9999831538 You Don't Need to Know What's Inside
5.9999835137 Redefining the PC -- and Mathematics As Well
4.9999999021 We Fixed It, Really
3.9998245917 Division Considered Harmful
2.9991523619 Why Do You Think They Call It *Floating* Point?
1.9999103517 We're Looking for a Few Good Flaws
0.9999999998 The Errata Inside
--
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| Stuart Priest, Computer Manager priest at yorvic.york.ac.uk |
| Protein Structure Group http://www.yorvic.york.ac.uk/~priest/ |
! Department of Chemistry |
| University of York Telephone : 44 1904 432592 |
| Heslington, York YO1 5DD, U.K. Fax : 44 1904 410519 |
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