Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!tektronix!tekcrl!tekgvs!toma
From: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 80386 versus 80387
Message-ID: <5139@tekgvs.LABS.TEK.COM>
Date: 15 May 89 14:45:34 GMT
References: <1427@uw-entropy.ms.washington.edu> <45900232@uxe.cso.uiuc.edu>
Reply-To: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 29

In article <45900232@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>There is a bug in the silicon of early 80386's that causes a total
>machine hang at random times if the following things all are true:

[ Lots of conditions ]

>6) The phase of the moon is wrong. This is very important. It
>   really doesn't happen often.

Actually, it can happen *very* often.  The other failure requirement which
you did not mention was 7) executing a floating point instruction when an
interrupt occurs.  All it takes is a heavily floating point intensive program.
In my case, I have Spice compiled running under PharLap DOS/EXTENDER and
one particular circuit simulation will crash an afflicted computer *every
time*.  I use it to check computers!

>
>My Model 80 was indeed afflicted. A new motherboard with a DX chip
>fixed the problem. IBM apparently didn't just want to replace the
>chip itself. Microway and Phar Lap claim that a DX chip alone will
>fix the problem, but I never tried this.

Also, ironically, seemingly all Intel motherboards (301, 301ATZ, and 302)
are afflicted.


Tom Almy
toma@tekgvs.labs.tek.com
Standard Disclaimers Apply