Path: utzoo!yunexus!ists!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.arch
Subject: Multiple coprocessors?
Message-ID: <1647@crdos1.crd.ge.COM>
Date: 17 Nov 89 20:38:51 GMT
Article-I.D.: crdos1.1647
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: GE Corp R&D Center, Schenectady NY
Lines: 23


  I was told several years ago that the Intel 8086 could support up to
three coprocessors, because there was a two bit address field in the
escape. Does this sound familiar to anyone? I looked in my 286 manual
and didn't see it, but I can't put my hand on the original 8086 manual,
or I might have just missed it.

  The person who told me this was a hardware hack, and described a
system which used to 8087's and a custom multi-chip unit. The program
wasn't funded, he left the company, and I saw something in another group
about this.

  I thought Cray looked at multi-vector units per CPU and decided that
they ate too much bandwidth, but a chip like the 8087 has a better
ration of CPU time to memory bandwidth and could possibly get a big
boost in performance.

  Yes I know the software would be messy.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon