Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ulowell!masscomp!mod
From: mod@masscomp.UUCP (Michael O'Donnell x2915)
Newsgroups: comp.arch
Subject: Re: Claimed bug in 80286
Summary: It's true
Message-ID: <1781@masscomp.UUCP>
Date: 4 Aug 89 18:15:10 GMT
Reply-To: mod@velcro.UUCP (Michael O'Donnell (508)392-2915)
Organization: Concurrent Computer Corporation - Westford, MA
Lines: 29




I was working at another company back in 1984 and if it wasn't us that
brought this problem to Intel's attention, I'm fairly certain we were the
first non-Intel folks to know about it.  I'd have to go back and look at
my notes for details, but it involved the NMI and INTR signals.  I seem to
recall that there is(was?) a window of time during the NMI acknowledgement
phase where, if INTR wiggles it is not noticed and gets lost.  Or maybe
it's the other way around.  Anyway, Intel provided a very simple (two
gates) circuit diagram as a hardware fix and also some suggestions for
software fixes, both of which seemed to do the trick.  I don't know if the
later steppings of the 80286 incorporate a real fix, but I presume that
they do.



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   Michael O'Donnell
   Porting and Peripherals      (508)392-2915             home(508)937-0790
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   Concurrent /__________/
     Computer Corporation        1 Technology Way
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  DISCLAIMER: My opinions only coincidentally resemble those of my employer.
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