🚀 go-pugleaf

In article <1gqvidINNiel@hpscit.sc.hp.com> matthias@nsr.hp.com (Matthias Kamm) writes:
>|S| Norbert Juffa (S_JUFFA@iravcl.ira.uka.de) wrote:
>: In <1992Dec15.101259.6401@sei.cmu.edu> griest@ajpo.sei.cmu.edu writes:
>: 
>: > I have been told that you can install a 16MHz '387DX in a coprocessor
>: > socket to work with a 33MHz '386DX and it will work ok (running Math
>: > instructions at the 16MHz rate).  I am not convinced.  Has anyone done
>: > this?  How does it work?  Are their any jumpers that must be set?
>: > 
>: >    Tom
>: > 
>:
>You're probably mixing up the 287 with the 387.  The 286 coprocessor, the
>287, runs asyncronously to the motherboard clock, and therefore can be
>used at different speeds than the main cpu clock.  In fact, my 4 year
>old 386 20Mhz motherboard has a 287 socket in it, and I'm using an Am287
>12Mhz.  It works great, and is cheap as heck ;->
>
>The 387 is syncronous, and therefore must be rated at the same speed as
>the motherboard cpu i.e. you need a 387DX-33.  


You should tell this to Micronics who have sold 386/33 mother boards
that could use 387's of various speeds, all you had to do was change
the xtal for the 387, and set a jumper.

It's a simple question of motherboard design.

-- 

Rick Kelly	rmk@rmkhome.UUCP	unixland!rmkhome!rmk	rmk@frog.UUCP