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From: scotte@locus.com (Scott D. Eberline)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: 33 MHz 387 asynchronous with 25 MHz 386
Message-ID: <24449@oolong.la.locus.com>
Date: 15 May 91 22:44:31 GMT
Lines: 22

Has anybody hooked up a 387 running asynchronously at 33 MHz to something
like the following:

	Mylex MX386 motherboard
	25 MHz 80386DX
	80 ns RAM

The motherboard has a socket for an oscillator for running a coprocessor
asynchronously.

I'm considering the Cyrix EMC87 coprocessor, if that matters.

A Mylex Tech Support guy didn't know one way or the other, but suggested
running a coprocessor at the CPU speed for reliability.  The Intel 387
programmer's reference says that the ratio of the coprocessor clock to
the CPU clock must be between 10/16 and 16/10, so the 386 ought to work
with coprocessors at up to 40 MHz, but I don't know what subtleties are
introduced by specific motherboards.

Does anybody know of reasons why this would not work?
-- 
Scott D. Eberline			scotte@locus.com  or  lcc!scotte