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From: peter@sugar.UUCP (Peter da Silva)
Newsgroups: comp.sys.amiga
Subject: Re: Argument for Virtual Memory
Message-ID: <1089@sugar.UUCP>
Date: Thu, 19-Nov-87 21:40:38 EST
Article-I.D.: sugar.1089
Posted: Thu Nov 19 21:40:38 1987
Date-Received: Sun, 22-Nov-87 19:37:32 EST
References: <8711151944.AA25448@cory.Berkeley.EDU>
Organization: Sugar Land UNIX - Houston, TX
Lines: 31

Just a quick interjection.

Some of youse guys seem to be confusing:

	1. Virtual memory.

	2. Protected memory.

	3. Memory Management.

Memory management is when the address space seen by a program differs from
the real address space.

Virtual memory is what you have when part of the memory a program uses isn't
in real RAM, but is copied in from secondary storage on demand. This usually
requires memory management.

Protected memory is when part of the address space is protected from reading
and/or writing. This usually is part of memory management systems.

Protected memory is a good idea. Memory management may be a good idea.
Virtual memory probably isn't a good idea. Protected memory should be
fairly easy to integrate with the Amiga O/S... just make MEMF_PUBLIC
mean shared memory, MEMF_PRIVATE private and protected memory. Memory
management will be tougher, but not too difficult. Just map managed
memory above the 16 meg 68000 limit, and keep all the IO in the 68000
address space. Virtual memory is going to be pretty tough, and is probably
Not even desirable, given the low cost of real memory.
-- 
-- Peter da Silva  `-_-'  ...!hoptoad!academ!uhnix1!sugar!peter
-- Disclaimer: These U aren't mere opinions... these are *values*.