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From: chuck@dartvax.UUCP (Chuck Simmons)
Newsgroups: net.arch
Subject: Re: Why Virtual Memory
Message-ID: <3729@dartvax.UUCP>
Date: Wed, 23-Oct-85 21:58:47 EDT
Article-I.D.: dartvax.3729
Posted: Wed Oct 23 21:58:47 1985
Date-Received: Fri, 25-Oct-85 04:08:38 EDT
References: <480@seismo.CSS.GOV>
Organization: Dartmouth College, Hanover, NH
Lines: 14

> Why virtual memory when physical memories are getting larger?
> 
> Protection and resource allocation.

Another reason for virtual memory is that segmented architechtures can
make programming easier.  For example, some programs want to have multiple
stacks (eg our PL1 compiler).  By setting up each stack as a segment,
the compiler programmer can easily and efficiently allocate storage on
any stack.  Our current pl1 compiler, written before we had a segmented
architechture, must spend a lot of time worrying about stack collisions.
When one of these occur, it must shuffle the stacks around in core to move
them away from each other.

-- Chuck