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From: mwm@VIOLET.BERKELEY.EDU.UUCP
Newsgroups: mod.computers.68k
Subject: Small systems & MMU's
Message-ID: <8702240242.AA14178@violet.berkeley.edu>
Date: Mon, 23-Feb-87 21:42:35 EST
Article-I.D.: violet.8702240242.AA14178
Posted: Mon Feb 23 21:42:35 1987
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>> I find it hard to believe that you are not just joking!  You obviously like
>> the flavor of your foot, but I guess we all are entitled to an opinion.

Yup. And some of us go out of our way to look at the facts behind
other peoples opions before flaming about them.

>> I, too, had a small system, but I learned that a UNIX type system, with 
>> memory managment, Vmem, process forking, etc., unleashes power one couldn't
>> dream of before.  I suggest you send your messages about things you obviously
>> have no knowledge about to /dev/null.  That is, type 'cat > /dev/null'...

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?
If not, "how come you ain't rich?" :-)

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. An MMU would still be nice, though. But if I can save 10% of
the cost of producing a box, and I'm planning on selling it in a
market that doesn't need an MMU, then I'd be stupid to put one in.

For instance, that's why the Amiga doesn't have an MMU; the looked at
it, and were looing at $125 for the CPU board. Even at $10 for the
parts (and who knows what for the board space), that's not a good
trade. If you think you have to have an MMU, then either wait for the
cost of MMU'ed systems to drop, or spend several times as much money
as you would for a system without one.

As for Unix proper - it's got serious problems. The worst is that the
system calls have long since gotten past the point of having been
designed, and have "grown" to be what they are. Starting over from
scratch, and building a system that emulates Unix on top of a
reasonable OS (which is what Minix is) is a _good_ thing. Period. The
trick is to then get all those Unix utilities (hopefully, after
rewriting them to regularize the argument parsing & delete cruft
that's been added to solve problems you solved in a better way)
running on your system. That's harder, 'cause you have to talk AT&T
out of the sources, or rewrite all of them.

	<mike