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From: neighorn@qiclab.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: 80286/80287/80386/80387
Message-ID: <447@qiclab.UUCP>
Date: Mon, 11-May-87 05:00:11 EDT
Article-I.D.: qiclab.447
Posted: Mon May 11 05:00:11 1987
Date-Received: Wed, 13-May-87 07:29:31 EDT
Reply-To: neighorn@qiclab.UUCP (Steven C. Neighorn)
Distribution: world
Organization: Qic Laboratories, Portland Oregon
Lines: 31

In a previous article, Michel Bruneau writes:

>It is a well know fact that the 8086-8087 combinaison beats easily the
>80286-80287 setup in term of numbercrunching speed (at least for the
>Fortran programs I use!) .. Now that the 80386 is out, is there a
>math-coprocessor that will come with it , and can we expect real output
>from it (i.e. speeding up 20 times or more, like the 8087 did with the 8086)?

While it is true the combinatation of an 8086/8087 surpasses the number
crunching output of the 286/287 pair operating at similar clock speeds,
this is not always the case. Higher speed 286/287 combo's (ie 10-12Mhz)
are faster than the slower speed 86/87 pair. The speed differential is
due mainly to the 80287 accessing memory through the 80286 due to 
protection schemes, where the 8087 does not have this requirement.

Early results with the 16Mhz 80386/80387 show the numerical throughput
of the 80387 to be 5-6 times that of the 80287. This is good news to me,
for I am one of those lucky individuals with a 10Mhz 80287 on an emulator
board stuck in the 80387 socket. f their 80386 machine.

Another problem is the complete lack of software to take advantage of the
extra functionality on the 80*87 chips. MSDOS, in all its glory, will never
do much more than make the higher end math coprocessors run 8087 code.
Only unix and xenix take advantage of the 80287's added instructions. Who
knows what Microsoft's 'soon-to-be-released' OS/2 will do with the chip.

Another case of unused potential! :-)
-- 
Steven C. Neighorn                tektronix!{psu-cs,reed}!qiclab!neighorn
Portland Public Schools      "Where we train young Star Fighters to defend the
(503) 249-2000 ext 337           frontier against Xur and the Ko-dan Armada"