Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!rutgers!cunixf.cc.columbia.edu!peter
From: peter@cunixf.cc.columbia.edu (Peter Wu)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 486SX - Intel now telling lies
Message-ID: <1991May25.192449.27061@cunixf.cc.columbia.edu>
Date: 25 May 91 19:24:49 GMT
References: <1561@aoa.UUCP> <1991May23.205937.25386@rodan.acs.syr.edu> <9105241448.AA14412@iecc.cambridge.ma.us>
Reply-To: peter@cunixf.cc.columbia.edu (Peter Wu)
Organization: Columbia University
Lines: 29

In article <9105241448.AA14412@iecc.cambridge.ma.us> johnl@iecc.cambridge.ma.us (John R. Levine) writes:
>In article <1991May24.152912.1601@rodan.acs.syr.edu> you write:
>>   I have just received email indicating a claim that the new intel 486-sx
>>will not be pin compatible with existing 486's.  ...

The latest issue of PC Magazine confirms this.

>Given the existence of the so-called 487SX, the 486SX cannot be pin
>compatible with a 486.  Remember that the 487SX is in fact an entire 486
>which takes over from the 486SX; you could probably throw away the 486SX when
>you install a 487SX.  But, the 487SX is very expensive, considerably more
>than a real 486.  If the 486SX were pin compatible with the 486, then one
>could skip the overpriced 487SX and instead install a real 486 to get
>floating point.

The 486sx has one extra pin than a 486dx.  That one extra pin will be
used to deactivate the chip.  When the 487sx is plugged in, it will
deactivate the 486sx and take over everything itself.  The 486sx
itself has the math co-processing stuff, but is deactivated at the
factory.  Apparently this was the most cost efficient way to produce
the chip. :(

>Regards,
>John Levine, johnl@iecc.cambridge.ma.us, {spdcc|ima|world}!iecc!johnl

PQ?
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Pedro Quien?		peter@cunixf.cc.columbia.edu		Peter K. Wu
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