[comp.sys.ibm.pc.hardware] Different speed math co-processor

pshuang@athena.mit.edu (Ping-Shun Huang) (06/20/91)

I would like to know if you can use a 80387 which is a different speed
than the i386 CPU on the same motherboard.  I seem to recall reading
something in the past about there being a separate crystal and that
therefore the 8038_ family was the first where you could mix and match
different speeds.  Does anyone know the technical details or have tried
this and either failed or succeeded?

(The reason I wish to know is that as a student on a tight budget, I
would be willing to buy a 80386-16 rather than a 80386-33 even though I
would be taking a hit on FLOPS if I can get a substantially better price.)

--
Above text where applicable is (c) Copyleft 1991, all rights deserved by:
UNIX:/etc/ping instantiated (Ping Huang) [INTERNET: pshuang@athena.mit.edu]

ianhogg@cs.umn.edu (Ian J. Hogg) (06/21/91)

In article <PSHUANG.91Jun19193149@beeblebrox.mit.edu> pshuang@athena.mit.edu (Ping-Shun Huang) writes:
>I would like to know if you can use a 80387 which is a different speed
>than the i386 CPU on the same motherboard.  I seem to recall reading
>something in the past about there being a separate crystal and that
>therefore the 8038_ family was the first where you could mix and match
>different speeds.  Does anyone know the technical details or have tried
>this and either failed or succeeded?
>
  I've been running a 20Mhz 387 in a 33 Mhz 386 system since February with
no known problems.  I don't know if it is "officially" OK to do this though.


>(The reason I wish to know is that as a student on a tight budget, I
>would be willing to buy a 80386-16 rather than a 80386-33 even though I
>would be taking a hit on FLOPS if I can get a substantially better price.)
>
>--
>Above text where applicable is (c) Copyleft 1991, all rights deserved by:
>UNIX:/etc/ping instantiated (Ping Huang) [INTERNET: pshuang@athena.mit.edu]


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Ian Hogg						ianhogg@cs.umn.edu
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