Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!uunet!brunix!cgy
From: cgy@cs.brown.edu (Curtis Yarvin)
Newsgroups: comp.arch
Subject: Re: Von Neumann Architectures
Message-ID: <70170@brunix.UUCP>
Date: 28 Mar 91 21:36:53 GMT
References: <5104@ns-mx.uiowa.edu>
Sender: news@brunix.UUCP
Reply-To: cgy@cs.brown.edu (Curtis Yarvin)
Organization: Brown University Department of Computer Science
Lines: 40

In article <5104@ns-mx.uiowa.edu> jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879) writes:
>The claim that an architecture is or is not a Von Neumann architecture
>is very frequently made in a misleading way.
...
>pointing out that essentially all modern architectures contain features
>which are quite correctly described as such.

>The next page of this note contains a list of popular non-Von Neumann
>features in modern architectures:
>1) Indexed addressing.
>2) Indirect addressing.
>3) Multiple accumulators.
[et cetera]

The next line of this note contains a list of popular non-Von Neumann
features in modern architectures:

1) Transistors.

Mr. Jones and the original poster (Firth?) are talking about two quite
different things.  Mr. Jones mentions a few _additions_ to the Von Neumann
concept of a computer.  These are, unsurprisingly, numerous.  Computer
architecture has made a few minor advances in the past 40 years.

The original poster, however, was vilifying features of modern machinery
which represent _reductions_ of the capability of Von Neumann machines.

For example, an ideal Von Neumann computer has an individual data/instruction
space; it can execute data or modify instructions.  Most modern processors,
however, separate I- and D- caches, often resulting in some loss of the
ability to execute self-modifying code.

It is, however, possible to get into fierce but meaningless arguments over
whether segments represent such a reduction.

Curtis

"I tried living in the real world
 Instead of a shell
 But I was bored before I even began." - The Smiths