Intel Admits Bugs in 486; Says Clean Chips Ship Next Month
 
Microbytes Daily News Service
Copyright (c) 1989, McGraw-Hill, Inc.
Intel acknowledged officially this week that its 80486 CPU has
two significant bugs that slipped by unnoticed until several
thousand chips had already been shipped to customers. Intel
says the bugs will be fixed and new chips will go out by the
end of November.
 
According to Intel, the bugs involve two functions of the 486's
floating-point unit, which is built into the same chip as the
CPU. The first problem shows up when executing a special
sequence of FPTAN and FSINCOS instructions (these are
instructions that compute the tangent and sine and cosine
trigonometric functions). The sequence is rare, and it only
causes a problem with some values -- but the bug can cause
incorrect or erratic results. The other bug shows up in
floating-point error handling; for example, when the FPU tries
to divide a number by zero. Again, the sequence that triggers
the bug is rare, but it can cause erratic results. The bugs
could show up when using any programs that crunch numbers,
which includes CAD and graphics software and packages like
Lotus 1-2-3.
 
Thousands of the buggy chips have gone out. Intel claims its
customers have asked the company to continue shipping the chips
so that there will be plenty of 486 machines on the floor at
Comdex in two weeks. The corrected chips head for the production
line next week at Intel. But those chips won't start out the door
for nearly a month.
 
Intel says it's advising its customers not to put the buggy
chips in machines that will be used for technical applications
but claims that they're probably safe for dedicated machines
like file servers.
 
                              --- Frank Hayes
 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
