Date   : Fri, 20 Oct 1989 17:08:00 GMT
From   : gem.mps.ohio-state.edu!ginosko!cs.utexas.edu!uwm.edu!mailrus!jarvis.csri.toronto.edu!torsqnt!tmsoft!masnet!canremote!greg.trice@tut.cis.ohio-state.edu (GREG TRICE)
Subject: Turbo Modula-2 REL prob

Use the NS32081 FPU. This chip is designed for the NS32000 family but
its interface is general enough to work with any cpu. It does not depend 
in any way on unique features of the 32000. You will have a lot of grief 
trying to interface an 8087 or 287 to any non-Intel chip, and not much
less problem with the MC68881. But an interface for the 32081 can be
done in 3-4 TTL chips or one PAL. National themselves publish an
application note (I have a copy - if you have FAX I can send it to you).
 I have successfully interfaced the 32081 to both the HD64180 in my
XLM-180 and the Z-280 in an experimental homebrew machine (an AT with a
brain transplant). I've memory-mapped mine into an unused buffer area in 
the middle of the Z3 data areas and written a little routine that allows 
it to be called by a BDOS call. The beauty of this is that it makes code 
portable between FPU equipped and non-FPU equipped machines. Those
without FPUs can intercept the call and substitute a call to an RSX that 
does the FP calculations in software.
 If you're interested I'll put together some notes on my 32081
applications. National now have the 32581 which is 10-15 times faster
(but much more expensive) and needs a 32 bit bus. The 081 runs with an 8 
or 16 bit bus.
 Hoping this is some help.
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