Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!uakari.primate.wisc.edu!pikes!boulder!stan
From: stan@Solbourne.COM (Stan Hanks)
Newsgroups: comp.arch
Subject: Re: parallel systems
Message-ID: <2896@stan.Solbourne.COM>
Date: 25 Oct 89 16:15:20 GMT
References: <35825@lll-winken.LLNL.GOV> <20336@princeton.Princeton.EDU> <7651@bunny.GTE.COM> <1989Oct23.152120.25967@cs.rochester.edu> <6655@ficc.uu.net>
Reply-To: stan@Solbourne.com (Stan Hanks)
Organization: Solbourne Computer Inc., Longmont, Colorado
Lines: 26

In article <6655@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>Also, the job of programming a shared memory system is a lot harder than
>programming a system with messages as the communication medium. The number
>of successful message-based operating systems demonstrates this.

Not necessarily so. It just demonstrates that there is more hardware 
available with which to build message-passing operating systems.

It's bunches easier to build the hardware needed for a message passing 
system -- all you need is CPUs with memory and some messaging media 
connection, right? You can use PCs with serial lines in the trivial 
case, on up to some sort of massively parallel system in the more 
complex. You can't even begin to count the number of ways that you 
can construct such a system.

It is however substantially more complicated to construct a shared memory
system. If you don't believe me, count the number available (relative
to the number of systems which have the hardware necessary to build
a messaging system). Or, try building one yourself sometime.... 8{)

Regards,

-- 
Stanley P. Hanks  Science Advisor                      Solbourne Computer, Inc.
Phone:            Corporate: (303) 772-3400             Houston: (713) 964-6705
E-mail:           ...!{boulder,sun,uunet}!stan!stan          stan@solbourne.com