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From: tomk@intsc.UUCP (Tom Kohrs)
Newsgroups: comp.sys.intel
Subject: Re: POPF still broken in 286?
Message-ID: <405@intsc.UUCP>
Date: Tue, 18-Nov-86 14:26:10 EST
Article-I.D.: intsc.405
Posted: Tue Nov 18 14:26:10 1986
Date-Received: Tue, 18-Nov-86 23:45:35 EST
References: <2646@gitpyr.gatech.EDU>
Organization: Intel Sales, Silicon Valley, Ca.
Lines: 38

>    IBM put a warning in the AT Technical Reference, and I can remember 
> several people complaining about a problem with the POPF instruction that
> allowed interrupts to be processed even when interrupts had been disabled.
> Was this problem fixed in subsequent masks for the 286, or does it still
> exist?
> 
The problem with the POPF instruction (it would always enable interrupts)
was only in the B-step parts (identifiable by markings of (c) Intel'82 or
(c) Intel '83).  The C-step and E-step have this problem fixed.  Almost all
of the B-step parts that were shipped went to IBM.

>    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.   Given that increasingly complicated architectures
						^^^^^^^^^^^
> are showing up in most microprocessor families, it would seem that additional
> testing is in order.  Is anyone familiar with the testing cycles that go
> on for microprocessors? 

Complicated is the key word. As architectures become more and more complicated
it takes longer to generate all of the test vectors necessary to prove the 
design.  Initial part testing takes two forms. Running software from a previous
part (the 8086 in the case of the 286) and specific vectors designed to stress
the part.  How much gets found and fixed before the parts ship in volume has
more to do with marketing considerations than the technical correctness of
the chip.  Long term testing is done by trying to put the chip through every
conceivable sequence of events (both hardware and software) and by following
up on problem reports from the field. You would be amazed at what some people 
will try to do to a chip.
-- 
------
"Ever notice how your mental image of someone you've 
known only by phone turns out to be wrong?  
And on a computer net you don't even have a voice..."

  tomk@intsc.UUCP  			Tom Kohrs
					Regional Architecture Specialist
		   			Intel - Santa Clara