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From: jru@etn-rad.UUCP (John Unekis)
Newsgroups: comp.sys.ibm.pc,comp.sys.intel
Subject: Re: 16bit 386 chips!
Message-ID: <307@etn-rad.UUCP>
Date: Tue, 17-Nov-87 13:49:23 EST
Article-I.D.: etn-rad.307
Posted: Tue Nov 17 13:49:23 1987
Date-Received: Fri, 20-Nov-87 03:30:35 EST
References: <5011@oberon.USC.EDU> <2139@lsuc.UUCP> <752@neoucom.UUCP>
Reply-To: jru@etn-rad.UUCP (John Unekis)
Organization: Eaton Inc. IMSD, Westlake Village, CA
Lines: 24
Keywords: 386
Xref: mnetor comp.sys.ibm.pc:10253 comp.sys.intel:398

In article <752@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes:
>
>The early batches of '386 CPUs from Intel a\had about a 10% failure
>rate on 32 bit multiplies.  It is my understanding that the faliure
>was caused by a bug in the manufacturing quality control testing
>procedure.-- NOT a flaw in the architecture of the chip.
...
Nice try, but I dont think this is accurate. I beleive that
the flaw was in the chip design. The gates in the multiply ALU were
packed too closely together, and a zero bit surrounded by ones would 
be turned into a one by the induced charge from the surrounding cells.
The design flaw was not found before the chips were sold due to a lack
in intels quality control procedure- apparently no one in their QC
department thought of testing the ALU with alternating bit patterns.
A defective chip cannot be caused by poor QC procedures. What intel 
could have done, had their QC department been a little quicker on the
draw, would have been to remove the chips that actually failed from 
the production stream. They could have sold potentially defective chips
that didnt actually fail, and no one would have noticed while they fixed
their design internnaly. But look at it from intels point of view, Western
Electric had the WE32000, National had the 32032, motorola had the 68020,
all 32-bit processors. All intel had was the 16-bit lineup . They just
had to get something out to market to catch up with the competition. 
Under pressure like that it is understandable that mistakes might occur.