Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!pyrnj!pyrdc!uunet!portal!cup.portal.com!
From: R_Tim_Coslet@cup.portal.com
Newsgroups: comp.os.misc
Subject: Re: a very naive Question???
Message-ID: <10122@cup.portal.com>
Date: 18 Oct 88 03:05:14 GMT
References: <835@amethyst.ma.arizona.edu> <5085@medusa.cs.purdue.edu> <664@
Organization: The Portal System (TM)
Lines: 41

In <5102@medusa.cs.purdue.edu> 
	spaf@cs.purdue.edu (Gene Spafford) Writes:
>In article <664@cme-durer.ARPA> wallace@cme-durer.ARPA (Evan Wallace) writes:
>>In article <5085@medusa.cs.purdue.edu>, spaf@cs.purdue.edu (Gene Spafford) writes:
		[much deleted]
>teach OS, etc.  I *know* what virtual memory is.
>
>The definition I gave happens to cover the memory scheme on systems
>your definition doesn't -- like TSO on a 360, old NOS on a  CDC 6600,
		[more deleted]
>It's unfortunate that people don't understand what virtual memory is,
>and think that the way it is done in Unix is the only correct way.  Too
		[rest deleted]

This whole discussion is an example of how NOTHING is really standard
in computers and how people familiar with one usage of a term get all
confused (and ocasionally violent) in responce to an unusual or unfamiliar
usage of the same term.

I still remember the time I read some CDC (I think) documentation and
kept encountering the term "Stack" used in a manner that did not seem
to make sense ("everyone" knows that a "stack" is a push/pop data structure
usually used for saving return addresses, etc. on). I had read nearly
the whole document before I realized that that document was using the
term "Stack" to refer to what I was used to calling a "Memory Bank".

Had to reread the whole document to understand it, then   :-(


So as far as I am concerned... Both definitions of "virtual memory" are
valid (within the context in which they are defined). Although I tend
to agree that "virtual memory" only really requires that the program
"think" it is running in a different memory than may actually be present
on the hardware (and not have to do anything "on its own" to manage the
differences) regardless of whether that "virtual memory" is larger or smaller
than the "physical memory".

                                        R. Tim Coslet

Usenet: R_Tim_Coslet@cup.portal.com
BIX:    r.tim_coslet