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From: brendan@batserver.cs.uq.oz.au (Brendan Mahony)
Newsgroups: comp.sys.mac.hardware
Subject: Re: New Macintosh Strategy
Message-ID: <5494@uqcspe.cs.uq.oz.au>
Date: 31 Oct 90 06:04:16 GMT
References: <5485@uqcspe.cs.uq.oz.au> <1990Oct31.034316.22402@d.cs.okstate.edu>
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minich@d.cs.okstate.edu (Robert Minich) writes:

>Sorry, but VM does not equal protected memory. You can have neither,
>one, or both. Sys 7 will offer only VM...

Sorry to hear that. Sounds like a waste of space then.

In my first year CS course VM did imply protected memory. Every process
has its own (virtual) copy of the full machine address space. The PMU converts
a virtual address to a physical address, be it in main memory or on
disc. The weaker form of memory management was called paged memory
management.

|> Another point is that VM reduces the complexity of the code writing
|> process, which cannot be bad for the end user. If makes things easier
|> for the programmer you need it.

>Wow, with more memory to work with, I'll be inspired to create really
>good code. This is going to be great!

You miss my point. VM means that programers do not need to worry about
the size or availability of code segments, or for that matter have
segments at all. This is the reduction of complexity to which I refer.

--
Brendan Mahony                   | brendan@batserver.cs.uq.oz       
Department of Computer Science   | heretic: someone who disgrees with you
University of Queensland         | about something neither of you knows
Australia                        | anything about.