Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!boulder!unicads!les
From: les@unicads.UUCP (Les Milash)
Newsgroups: comp.arch
Subject: Re: SISC
Message-ID: <422@unicads.UUCP>
Date: 5 May 89 22:22:39 GMT
References: <112@centaure.UUCP>
Reply-To: les@unicads.UUCP (Les Milash)
Distribution: usa
Organization: Unicad  Boulder, CO
Lines: 39

In article <112@centaure.UUCP> cliff@centaure.UUCP (Clifford Dibble) writes:
>Single Instruction Set Computer
>The SISC extends the concept of RISC architecture to the fullest degree

In Dan Hillis's book about the connection machine he calls it "the ultimate
RISC" cause it has 1 (albeit very powerful) instruction. and he's not joking;
it's sort of a 16 dimentional hypercube of soft-settable pals-with-sram;
each instruction tells the (1-bit) alus what to do and who to do it to.

actually, y'all might enjoy reading this book--only take an evening--even
tho it's an SIMD and we're all into MI?Ds apparently.  
the machine is really radical, but nevertheless one of the languages (C*) 
is amazingly normal considering this is a massively parallel SIMD.

the guy always thinks in "the limit as N -> infinity"; it's that perspective
that kind of turned me off to shared memory machines or to busses (i mean
isn't it basically true that lim (N->oo) {sharing memory} = starvation?
(i'm now shudder in fear and donning my asbestos panties cause i realize
that that's probably a very controversial thing to say (in fact i'd rather
y'all'd just call back and call me a Sh*thead in all caps rather than have us
do a big war about it)) but ain't that basically the truth?  shared memory
works as long as you don't try to share it (that's what snoopy caches
are hoping for?); message passing works as long as you don't need to pass 
many; all these approaches we can milk for another order of magnitude or 
two but basically the problem is very difficult?  right?

the book re-inspires me that "there are other Very Odd architectures out 
there waiting to be discovered; some of which are Very Useful".  After all,
this is the age of Very Unusual Architectured Computers, right?

sigh.  too bad some naive nerd like myself can't just invent The Ultimate
Computer and get rich and famous.  our problems are difficult problems.
after reading the VLIW/Superscalar/Superpipelined article in ASPLOS III 
i thought that there are so many tradeoffs, this'd never be easy. y'all
do pretty well, what we have is amazingly fast.

(sorry to blab on for so long)

Les Milash