Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!samsung!noose.ecn.purdue.edu!en.ecn.purdue.edu!stevew
From: stevew@en.ecn.purdue.edu (Steven L Wootton)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: fastest 287?
Message-ID: <1991Mar17.222637.4437@en.ecn.purdue.edu>
Date: 17 Mar 91 22:26:37 GMT
Organization: Purdue University Engineering Computer Network
Lines: 39


I've decided to put together the 80287 Socket Rocket described in the April
1991 issue of ComputerCraft Magazine.  This will be done purely for its
experimental value.  To that end, I need to know a couple of things about
80287 floating-point processesors.

First, I would like to use the most efficient 287 out there.  There are
three major contenders for the project (that I know of):

Intel 80287 XL  ($185)
IIT   2c87-20   ($190)
AMD   80287     ($100)

Have these three chips been benchmarked against each other at the same
clock speed to determine which is the fastest?  I remember a BYTE article
showing that the AMD chip is slower than the Intel chip, but I don't recall
hearing anything about the IIT.

Second, I would like to use the chip which can be safely driven at the
highest possible clock speed.  Adding a heat sink is no problem, and I am
planning on doing that anyway.  Could any of these chips run at 33MHz?
25MHz?  If not, how fast? 

If a less-efficient chip (like the AMD) could run at a higher clock speed
than a more-efficient chip (like the 287XL), then I would probably go with
the higher clock speed, if it would yield a greater overall floating-point
throughput.

Perhaps a better question: how do these things fail if the clock speed is
too high?  If they tend to catch fire, that would tend to discourage high-
speed experimentation :-)

All suggestions, hints, info, and questions are welcome.  You can post
replies or send email; either would be fine.  Thanks.

Steve Wootton
stevew@ecn.purdue.edu
stevew@pur-ee.uucp
stevew%ecn.purdue.edu@purccvm.bitnet