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From: bandy@amdcad.UUCP.UUCP
Newsgroups: mod.computers.68k
Subject: Re: Small systems & MMU's
Message-ID: <8702241756.AA22311@amdcad.AMD.COM>
Date: Tue, 24-Feb-87 12:56:53 EST
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Posted: Tue Feb 24 12:56:53 1987
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>>> I, too, had a small system, but I learned that a UNIX type system, with 
>>> [...] Vmem [...] unleashes power one couldn't dream of before.
>
>Gee, the biggest, fastest Unix box I can get to (both legitimately and
>otherwise) doesn't have VM. Their attitude is "Real memory for real
>performance."  Maybe the hardware designers know something you don't?

Right, while it doesn't have vm, it does have memory management - upper
and lower bounds registers, if I remember properly.  It has just enough
memory management to keep people separated from each other.

>There's a place for everything. Given a 68K based system, I'd rather
>not have virtual memory - just give me 16Meg of real, and forget the
>virtual.

Right.  If you don't have applications that run in more memory *than you
can afford*, then you don't need vm (aside from the fact that with it you
can cut down your swapping).  Now, I can't afford to put together more
than 256k worth of ram (I have to start haunting the surplus shops and
try to find some *cheap* ram) in my system and I'd really rather not try
to swap to a slow device (or use the "parent and child run in the same
address space" approach -- *slow*!), so it seems that for me, putting an
mmu of any sort into my system (even a 68451) is a win -- it makes unix
run much cleaner and it allows me to make the best of the small system
that I have.

	andy
-- 
Andrew Scott Beals, {lll-crg,decwrl,allegra}!amdcad!bandy +1 408 749 3683