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From: jgay@digi.lonestar.org (john gay)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: How much for a 487SX?!!
Message-ID: <1991Apr26.165405.4679@digi.lonestar.org>
Date: 26 Apr 91 16:54:05 GMT
References: <1991Apr26.002911.1793@agate.berkeley.edu>
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Lines: 25

From article <1991Apr26.002911.1793@agate.berkeley.edu>, by c60b-1eq@e260-1a.berkeley.edu (Noam Mendelson):
> In article <1991Apr25.132715.1945@cbnewsh.att.com> rkl@cbnewsh.att.com (kevin.laux) writes:
>>	Um...Correct me if I'm wrong, but isn't one of the differences
>>between DX and SX that the DX can do 32-bit accesses while the SX can do
>>only 16-bit (like the 386DX vs the 386SX)?  This would mean you couldn't
>>just replace the 486SX with the 486DX to get the FPU functionality.  Also,

> You're wrong.  But Intel's naming strategy is completely inconsistent.
> The 386SX is a 386DX with a 16-bit external data path.  The 486SX is
> a regular 32-bit 486 sans math coprocessor.
> To be consistent, Intel should've named the 386SX a 388.  Or at least
> they could be consistent with their 'SX' label.

I think intel is being consistent with SX in their labeling.  You just have
to figure out what their labeling means.  Internally SX is really Sux so what
you have to figure is that a 386SX is a 386 that SuX somehow - with the
386SX they crippled the external bus path.  The 486SX SuX in that the
math co-processor is either disabled or just not there (conflicting reports on
that one).  Other than that (from what I have read) Noam is correct, although
I also believe part of what kevin says - the part about not being able to
directly replace a 486SX with a 486DX - I doubt that they are pin compatible
since intel is coming out with a 487SX for the 486SX and they have to talk
to each other somehow.

john gay.