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From: jsims@vuse.vanderbilt.edu (J. Robert Sims)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 80387 25MHz & 33MHz Questions (Was : 80387 25MHz question)
Keywords: math coprocessor, clones
Message-ID: <1991Apr18.211744.12564@vuse.vanderbilt.edu>
Date: 18 Apr 91 21:17:44 GMT
References: <298@sahara.cs.utexas.edu> <1991Apr9.161838.23008@engin.umich.edu> <3295@kluge.fiu.edu>
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In article <3295@kluge.fiu.edu> id8rld06@serss0.fiu.edu (Michael N Johnston) writes:
>>> 4) Do I need a different coprocessor socket for Weitec 80387 chips?
>
>The Weitec is NOT a clone of the 80387. There are a couple of versions
>of the Weitec for 386s. On is a chip the other is a chipset on a card.
>Both require a socket for the Weitec and will not work in the 80387
>socket.

Some clones _do_ use the same socket.  If you use an 80387, you insert the
chip in the middle of the PGA socket, and if you install a Weitek, it fills
the whole socket.  This means that you can't have both in your machine at
the same time, even though they can exist together if there are two sockets.

>    The Weitecs are not compatible with the 80387's nor do they claim
>be. The Weitec is in a different league from the 387s and cost a few
>hundred $'s more. It is a very high performance math coprocessor and
>is generally used for VERY intensive number calculations.

I have seen comparisons (PC Magazine?) that indicated that the Weitek's 
performance was quite exaggerated.  It was only blindingly fast with
certain special optimized benchmark programs, and in real applications
was only a little bit faster.  The only league difference is price.

>    A program that detects the 387 and uses it if present will not use
>the Weitec unless it is specificly designed to also work with the
>Weitec.

True.  However, almost nothing will use the Weitek.  The only packages I've
heard of that will are a few obscure finite element analysis packages, and
those will also use the *87 processors.

>    The other questions I will leave for others.
>
>Mike
>--
>====================================================================
>Michael Johnston
>id8rld06@serss0.fiu.edu or
>26793271x@servax.fiu.edu

Rob