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From: dan@prairie.UUCP (Daniel M. Frank)
Newsgroups: comp.sys.intel
Subject: Re: POPF still broken in 286?
Message-ID: <356@prairie.UUCP>
Date: Mon, 17-Nov-86 21:53:57 EST
Article-I.D.: prairie.356
Posted: Mon Nov 17 21:53:57 1986
Date-Received: Tue, 18-Nov-86 09:23:44 EST
References: <2646@gitpyr.gatech.EDU>
Reply-To: dan@prairie.UUCP (Daniel M. Frank)
Organization: Prairie Computing, Madison, Wisconsin
Lines: 38
Keywords: No Surprise

In article <2646@gitpyr.gatech.EDU> don@gitpyr.gatech.EDU (Don Deal) writes:
>   IBM put a warning in the AT Technical Reference, and I can remember 
>several people complaining about a problem with the POPF instruction ...
>
>   That a problem like this could occur (and has with vendors other than
>Intel) makes me wonder what kind of testing goes on before products are
>released to market.

   Recently, a friend of mine had some problems running a protected mode
operating system on an IBM AT.  He traced it to an early and buggy lot
of 286 chips, a few of which he was unlucky enough to receive via IBM.
On contacting IBM, he was told, "It's an Intel problem".  When he 
called Intel, he was told that IBM had been aware of the problem with
the early runs, and Intel had been unwilling to ship without a letter
from IBM acknowledging the problem and absolving Intel of liability.
IBM duly provided the letter, and Intel shipped the chips.

   I should note that this is hearsay.  Perhaps one of the folks from
Intel could be kind enough to confirm or deny it.  In any case, it 
takes a long time to prepare a Tech Ref manual, and even longer to
write the BIOS, which includes workaround code for many of these bugs.
It is almost inconceivable that IBM didn't know about the problems
long before the introduction of the AT.

	The AT is no miracle of engineering anyway.  The BIOS is filled
with funny delay loops and useless instructions all designed to pass
the time until the contents of device registers become valid.  Too
cheap to build the hardware right, I guess.  It's no surprise to me
that IBM also accepted bad chips and worked around the problems.
And protected mode?  No protected mode operating systems around
anyway, for years maybe.  I can't wait until p.m. DOS comes out :-).



-- 
    Dan Frank
    uucp: ... uwvax!prairie!dan
    arpa: dan%caseus@spool.wisc.edu