Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!a.gp.cs.cmu.edu!koopman
From: koopman@a.gp.cs.cmu.edu (Philip Koopman)
Newsgroups: comp.lang.forth
Subject: Re: Concurrency
Message-ID: <10555@pt.cs.cmu.edu>
Date: 24 Sep 90 16:15:02 GMT
References: <9009241330.AA06784@ucbvax.Berkeley.EDU>
Organization: Carnegie-Mellon University, CS/RI
Lines: 33

In article <9009241330.AA06784@ucbvax.Berkeley.EDU>, JAJZ801@CALSTATE.BITNET ("Jeff Sicherman,CSU Long Beach") writes:
> ... I'm mostly interested
> in Forth as a virtual machine for data flow architecture (does anybody
> talk about this anymore?) and multiprocessor architectures.

Data Flow is changing these days.  The folks at MIT seem
to have pretty much given up on some fundamental points and are
going to a more pipelined (e.g. RISC-like) architecture with
a large grain of interprocessor interaction parallelism.  See the
paper on Monsoon in the 1990 Computer Architecture Conference
Proceedings (pg. 82).  IMHO, the new research direction is giving up
a lot of the potential of dataflow (or, perhaps, it is an admission
that the potential never panned out).  (This assessment is my personal 
opinion; others (from MIT) claim that this is a natural outgrowth of
previous work).

BUT, fine-grain parallelism at a reasonably local level is gaining
in popularity.  This is localized data flow of the type that
has been around ever since the IBM 360/91 FPU days.
These days, the buzz-word is "superscalar execution"
(Intel 80960, IBM RS/6000, more announced almost weekly).
The question is: how do you get parallelism with Forth, given that the
stack would seem to create all sorts of artificial dependencies?
Making each operator into an array operator (such as John Dorband
has done with MPP Forth) is possible, but not really "data flow".
I haven't thought about this much, so maybe I missed something
obvious.

  Phil Koopman                koopman@greyhound.ece.cmu.edu   Arpanet
  2525A Wexford Run Rd.
  Wexford, PA  15090
Senior scientist at Harris Semiconductor, and adjunct professor at CMU.
I don't speak for them, and they don't speak for me.