FPU Bug in CPU

[kiernanf]

Can anyone explain the FPU bug? A diagnosic program I have says that my CPU has it. The CPU is an AMD Athlon 900 Mhz processor in a ECS K7VMA mainboard.

 

[CitrixEngineer]

The original bug involved the Intel Pentium (100-120Mhz, I think) incorrectly performing floating-point calculations with certain number combinations, with errors anywhere from the third digit on up.

Ways of testing your CPU to determine if it has this flaw.

Correct Answer
962,306,957,033 / 11,010,046 = 87,402.6282027341

Incorrect Answer
962,306,957,033 / 11,010,046 = 87,399.5805831329

Correct Answer
4,195,835 / 3,145,727 = 1.33382044913624100

Incorrect Answer
4,195,835 / 3,145,727 = 1.33373906890203759

Another way of testing for this flaw is to use Microsoft Excel and enter the following formula:

=4195835-((4195835/3145727)*3145727)

When entering this formula you should receive a returned result of 0


For more info, look here;

http://www.cs.earlham.edu/~dusko/cs63/fpu.html

Or, for more depth, look here;

http://x86.ddj.com/secrets/dan0411.htm

There is a utility to check for it here;

http://www.wrotniak.net/works/testfpu/

And some light relief here;

http://www.netfunny.com/rhf/jokes/94q4/pentiumd2.html

Enjoy