Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!ucsd!ucsdhub!esosun!seismo!uunet!super!rminnich
From: rminnich@super.ORG (Ronald G Minnich)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Address Space on the Amiga (was Re: Need info on exceptions)
Keywords: Queen's -, Florida -s
Message-ID: <673@super.ORG>
Date: 30 Aug 88 14:48:07 GMT
References: <8808272322.AA03740@cory.Berkeley.EDU> <125@fishpond.UUCP> <3859@hcr.UUCP>
Sender: uucp@super.ORG
Reply-To: rminnich@metropolis.UUCP (Ronald G Minnich)
Organization: Supercomputing Research Center, Lanham, MD
Lines: 35

In article <3859@hcr.UUCP> edwin@hcrvax.UUCP (Edwin Hoogerbeets) writes:
>I agree with Fred. The idea of a process is that the situation should
>look, to the process itself, as if it is the king of the CPU. No-one
>else is on this machine. If communication should occur, then you should
I could not disagree more. The reason is simple. There is an easy
way to do networking at the OS level within the framework of the
shared-memory model. You make the network look like a large shared 
memory. No less an authority than Vint Cerf (one of the creators
of tcp/ip) has said this is a good future direction for networking. 
A prototype of such a network has been built at udel, called 
MemNet. I have been working on how to use such a beast for 
around two years now. Hint: the obvious ways don't work well.
On the other hand, it sure makes networking easier.
   The goal is sharing of data. The way the amiga shares data leads
to a very high-performance, low-cost box. using my A500 windows is
a real relief after using a Sun 3-280 with X11 and their variable
latency and poor mouse response.
   Finally, i realized this morning that i screwed up the 
description of how Sprite works. Try again:
For all processes on a given sprite multiprocessor, address (e.g.) 0
will refer to the same piece of data. Now that may move around 
as pages are mapped etc, and not all processes may have access to
that page (e.g. there is protection), but given that a process has 
access to an address it will be pointing to the same piece of 
data as other processes that have access to that same address.
   Have i obfuscated enough yet? Sigh. For some reason i have
a hard time describing this, yet it is so simple and clean.
   Currently this hold for Unix kernel space, i.e. all the unix 
kernel space addresses are the same for all processes. 
All sprite does is extend that to kernel and user spaces. 
It makes sharing much nicer and eliminates lots of problems. 
ron
P.S. I think the days of 'king of the CPU' are numbered, if not gone.
People *like* building solutions that involve multiple workers. 
It is so much easier.