Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!POSTGRES.BERKELEY.EDU!dillon
From: dillon@POSTGRES.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga.tech
Subject: Re: 80860 as a math processor
Message-ID: <8905010604.AA20957@postgres.Berkeley.EDU>
Date: 1 May 89 06:04:45 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 28

:No, Richard meant it was a co-processor, like the 68881/2. Thats what
:the ads implied.
:
:So I called Weitek.
:
:Buggers.
:
:The stupid thing is memory mapped. You write the operands into
:memory addresses, then give it an operation, then poll it for
:completion. Some co-processor.

	The neat thing about the Weitek chip is that it has a stack.
Results are automatically pushed on the stack.  So, something like:

	(a + b) + (c + d)

	is: fpush a, fpush b, fadd, fpush c, fpush d, fadd, fadd, fpop (to) Mem

	That is, temporaries need not be moved off the FP unit.

	The sequent (parallel processor UNIX machine (running dynix)) uses
the Weitek chip.  Our current configuration has 12 386 boards (when you are 
running UNIX you generally don't care about the processor), each with a
Weitek fp unit.  While not a super computer, the thing can, running 12
compiles in parallel, compile all 246 C files (about half of postgres, the
rest being in lisp at the moment) in less than 5 minutes.

					-Matt