Path: utzoo!attcan!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.arch
Subject: Re: Dual FPUs?
Message-ID: <10250@cbmvax.commodore.com>
Date: 19 Mar 90 18:56:34 GMT
References: <24915@princeton.Princeton.EDU> <2157@crdos1.crd.ge.COM> <27907@cup.portal.com>
Reply-To: daveh@cbmvax (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 20

In article <27907@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes:
>The Compaq Systempro allows you to have both a 387 and a Weitek chip
>to be installed on the same 386 CPU.  

Since the Weitek chip is addressed as a peripheral device, rather than a coprocessor,
this is nothing out of the ordinary.  In fact, you could have as many Weitek chips
attached as you have memory space, at least logically (eg, I don't imagine Compaq
or much anyone else leaves room on their PCB for more than one).  With the '387 as
an Floating Point Coprocessor, there are probably a fixed number of FPU slots
available.  I don't know how many coprocessors a '386 would permit -- a 68030 allows
a total of 8, though one slot is permanently allocated to the MMU, leaving a real
limit of 7 external coprocessors.  The FPU normally sits in a standard coprocessor
slot; additional FPUs would require custom software to drive them, though that's 
probably the case for almost every architecture around.


-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
                    Too much of everything is just enough