Math coprocessors

From: Hotze <photze_at_batelco.com.bh>
Date: Mon Apr 6 21:50:42 1998

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_at_simconv.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Monday, April 06, 1998 9:34 PM
Subject: RE: Math coprocessors


>Ward Donald Griffiths III wrote:
>> Max Eskin wrote:
>> >
>> > 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.
>> --
>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
Received on Mon Apr 06 1998 - 21:50:42 BST

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