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From: amichiel@rodan.acs.syr.edu (Allen J Michielsen)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 287 in a 386-33 system?
Message-ID: <1991Feb27.001430.29482@rodan.acs.syr.edu>
Date: 27 Feb 91 00:14:30 GMT
References: <1991Feb19.080902.21887@amd.com> <1670@pdxgate.UUCP> <12816@darkstar.ucsc.edu>
Sender: amichiel@sunrise.acs.syr.edu
Organization: Syracuse University, Syracuse, NY
Lines: 28

In article <12816@darkstar.ucsc.edu> ted@helios.ucsc.edu (Ted Cantrall) writes:
>In article <1670@pdxgate.UUCP> mwizard@eecs.cs.pdx.edu (Craig Nelson) writes:
>>indra@brahms.amd.com (Indra Singhal) writes:
>>>Do 386 machines have a socket that allow using a 287?
>>>For a 33 Mhz 386 machine, what speed 287 should be used?
>>to my knowledge jamming a 287 in just won't work.  No Slot, wrong speed, get
>I suspect that this was a special design, but we have a 386 machine that
>has a 287 in it. This is an early 386, so there may not have been any 387's

   If anyone still cares, MANY early 386's did come with either or sockets for
80387's or 80287's.  Usually they also had a speed jumper for either or both
sockets to select appropriate production (projected) chips, like a 16 Mhz 387
or 12 Mhz 387 or 8/10 Mhz 287 or 6 Mhz 287.
   ANY as a matter of fact, INTEL themselves MADE and SOLD a 80287 to 80387 
conversion socket so you could plug in a 80287 into a 80387 socket, AND it had
a speed jumper on it so you could use production rated speeds for the 287.
99.999% of all software won't ever know the difference between a 287 in a 387
socket & a 387.  However, it is possible and especially now, with the prolif-
eration of 386 systems, programmers MAY not be reading the fine print or 
remembering these little details anymore.
  If I had a choice, I wouldn't consider a 287 ....
al


-- 
Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University
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