6 Apr
1998
6 Apr
'98
10:50 p.m.
Seriously look for a Weitek Math Co processor, especially if you've got lots
of RAM. They were 387-compatible FPU's that used some RAM to boost speed
dramatically. As a matter of fact, a Weitek might even be faster than a FPU
found on a Pentium or higher machine.
-----Original Message-----
From: Jack Peacock <peacock(a)simconv.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Monday, April 06, 1998 9:34 PM
Subject: RE: Math coprocessors
Ward Donald Griffiths III wrote:
Max Eskin wrote:
No, the Cyrix 486DL (I assume it is a DL or DR2 if it's in a 386
motherboard) is not the same as an Intel 486. The Cyrix 486DL was an
upgrade CPU for the 386 pinout, adding a 486 instruction set and 1K
internal cache. The 486DR2 version was clock doubled. These CPUs do
not have floating point. Generally an Intel 80387 did not work
reliably, but the Cyrix 487 co-processor did. ULSI (and I think IIT)
also made 487s. You can try the Intel 387, sometimes they ran ok,
mostly it depended on the speed range used.
Jack Peacock
I found a PS/2 Model 70 recently, which would normally have a 386,
but the previous owner installed a Cyrix 486 upgrade chip. Does
anyone know if I can use a 386 math coprocessor with this? I want
to run AutoCAD.
The i486 has a coprocessor built in, I assume that the Cyrix does
as well. Try the software. IIRC, AutoCAD doesn't _require_ a math
coprocessor, but one does help performance by an order or two of
magnitude on a 386.
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