AMD or Intel 80387 Math Coprocessor IC

From: Robert F. Schaefer <rschaefe_at_gcfn.org>
Date: Fri Feb 28 05:54:00 2003

----- Original Message -----
From: "Eric J. Korpela" <korpela_at_ssl.berkeley.edu>
To: <cctech_at_classiccmp.org>
Cc: <cctalk_at_classiccmp.org>
Sent: Wednesday, February 26, 2003 9:38 PM
Subject: Re: AMD or Intel 80387 Math Coprocessor IC


> > They come up on epay all the time, pick yer flavor. I just got a 40MHz
> > Cyrix Fasmath chip for $2 (includes $1 shipping) a week ago. Supposedly
> > clock for clock it's the fastest of the '387 FPUs, but IDK. Popped
right in
> > to to my P70.
>
> It was a tiny bit faster than the AMD and Intel parts depending upon
instruction
> mix.

Ah. Was it a 100% clone, or were there extra added instructions?

>
> > I'm still looking for a set of eight 2MB 72 pin IBM SIMMs with presence
> > detect, and a Cyrix 486Drx2, which is a 486 with a '386 pinout, if
anyone
> > has a spare.
>
> It's not quite a 486. It actually is a double clocked 386 with a small
> internal L1 cache. It doesn't share most of the instructions unique to
the 486.

Ok. I thought it was a 486.

>
> I don't currently have a DRX2, but I do have a DRX, which is essentially
the
> same thing without the clock doubled core. The L1 cache made it about 20%
> faster than an equivalently clocked 386. You had to explicitly turn on
the
> cache, and set regions as uncachable. (Caching the video card usually
made
> for problems.)

Guess I want the DRX2 then. No sense in spending all that time on something
just to have it be less than optimal. I'll have to dig up reference sheets
on 'em.

BTW, what do you run on the DRX? I'm upgrading an IBM P70 luggable, the
target OSes are AIX-PS/2 and Solaris in particular, and then as many others
as will work.

>
> Eric

Bob
Received on Fri Feb 28 2003 - 05:54:00 GMT