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From: koved@umcp-cs.UUCP
Newsgroups: net.arch
Subject: Re: Why not virtual files?
Message-ID: <6781@umcp-cs.UUCP>
Date: Thu, 26-Apr-84 19:38:30 EST
Article-I.D.: umcp-cs.6781
Posted: Thu Apr 26 19:38:30 1984
Date-Received: Fri, 27-Apr-84 06:50:05 EST
References: <333@oliveb.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 29

There have been several systems which treat ALL memory as a single
level store.  All memory references are to objects in the system,
and the underlying hardware/software takes care of the rest.
If the object being referenced is not in main memory (equivalent
to a page or segment fault), the system retrieves the object from
an external source (ie: disk, network).

This scheme is essentially the scheme proposed by the Smalltalk-80
LOOM (Large Object Oriented Memory) mechanism used to manage objects
in memory or secondary storage.  IBM System/38 does the same thing
in microcode (another obscure object oriented system).  The Intel 432
may work the same way.

The way around the addressing problem is to only allow references to
objects and offsets (ie: segment number, offset), and only the underlying
hardware knows about bits and bytes.

The uniform addressing aproach has a number of advantages.  If you are
interested, I can send you a paper which I am writing on a closely related
topic. 

Several systems use uniform addressing to refer to objects in main
memory, disk files, or on remote (distributed) systems.

Larry
-- 
Spoken: Larry Koved
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