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Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!floyd!harpo!seismo!rochester!ritcv!mjl
From: mjl@ritcv.UUCP (Mike Lutz)
Newsgroups: net.unix-wizards
Subject: Re: Berkeley Flame
Message-ID: <802@ritcv.UUCP>
Date: Mon, 14-Nov-83 21:36:20 EST
Article-I.D.: ritcv.802
Posted: Mon Nov 14 21:36:20 1983
Date-Received: Thu, 17-Nov-83 01:10:16 EST
References: ariel.518
Lines: 14

When I was just a lad in graduate school, we were very careful to distinguish
between address mapping and virtual memory.  The former simply meant that some
combination of hardware & software was able to take "logical" addresses pro-
duced by executing programs and map them onto different "physical" addresses.
However, for a system to support virtual memory, it had to maintain the illu-
sion that all of the logical address space was directly addressable, even
though some (most?) of the memory image was actually on secondary storage.
The virtual memory size has no predefined relation to the physical memory
size; if I remember correctly, the SDS940 system had a virtual address space
smaller than the physical address space.  The key is the ability to run a pro-
cess with only a small part of its address space loaded.

Mike Lutz
{allegra,seismo}!rochester!ritcv!mjl