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From: mig@cunixb.cc.columbia.edu (Meir)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 486SX - Intel now telling lies
Message-ID: <1991May29.191233.18863@cunixf.cc.columbia.edu>
Date: 29 May 91 19:12:33 GMT
References: <1991May23.205937.25386@rodan.acs.syr.edu> <9105241448.AA14412@iecc.cambridge.ma.us> <1991May25.192449.27061@cunixf.cc.columbia.edu>
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In article <1991May25.192449.27061@cunixf.cc.columbia.edu> peter@cunixf.cc.columbia.edu (Peter Wu) writes:
>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. :(

Hmm.  I wonder if you could just buy the 487.

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