Pentium 1 FDIV bug

[Guest]

Did you (or someone you know of) ever have annoying problems happen in real-life due to the Pentium 1 FDIV bug?

[wardrich]

never heard of it... do explain.

[Guest]

The FDIV bug is a defect in early Pentium 1 CPUs which can cause math errors when multiplying and dividing in the millions. An accountant dealing with millions of dollars could wind up with slightly inaccurate results. In most people's lives, the bug would not cause any grief. But in jobs that demand 100% accurate math where 7 digit numbers are used, the FDIV bug can cause trouble.

Intel offered replacements for the buggy CPUs. People could send in the old CPU and Intel would send a new fixed one at the same speed for free.

Pentium 60 to 100 had the bug but many systems with those CPUs don't.
Pentium 120 and above does not have this bug at all.

[wardrich]

Chances are then, my grandmother would have had the problem (she had a 75) but I had a sweet 126.

-Richard-

[Guest]

There are freeware programs that you can use to test to see if your Pentium 1 has the FDIV bug or not.

Try this one:

http://www.filelibrary.com:8080/cgi-bin ... cpuidf.zip

[[email protected]]

You can check to see if your Pentium has the FDIV bug by entering the following formula in the Windows calculator:
(4195835 / 3145727) * 3145727 - 4195835

If your CPU is ok, it will return 0.

[cheers_rules]

You can check to see if your Pentium has the FDIV bug by entering the following formula in the Windows calculator:
(4195835 / 3145727) * 3145727 - 4195835

If your CPU is ok, it will return 0.

I'm not sure that's always true. I may be mistaken, but I believe certain versions of Windows have been patched for this bug (especially NT).