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From: HELLER@cs.umass.edu.UUCP
Newsgroups: mod.computers.68k
Subject: 68000 O/S's, MMUs, et. al.
Message-ID: <8702181533.AA27804@ucbvax.Berkeley.EDU>
Date: Tue, 17-Feb-87 08:08:00 EST
Article-I.D.: ucbvax.8702181533.AA27804
Posted: Tue Feb 17 08:08:00 1987
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It seems that my recent message stirred up some dust.  First of all let me
clarify a few things.

First of I don't object to having a MMU.  It is just that I don't think a
MMU is *neccessary* for *most* applications.  In a development/hacker
environment and with real milti-user systems it is needed.  It is doubtfull
that MMUs will ever be common on *little* home/office systems (i.e. ST's,
Amiga's, Mac's etc.) - most of these system will be running well behaved
software (i.e. canned business and home software), so these system can
easily get by with an unprotected multi-tasking O/S (like OS9 or AMIGADOS).
I really doubt that UNIX/MINIX will ever be the O/S of choice amongst home
and office users:  UNIX is just too "weird" (why is the directory command
"ls"?  why is the type command "cat"? what is an inode? - only UNIX hackers
really understand UNIX).

Secondly, I have found that I have had little or no trouble with runaway
pointers totally trashing the system, at worst it just trashes the current
"process". Re-booting just that process is suffientent. I guess I tend to
write good code. Also, I have little need to run jobs in the background
much. I guess I am just a synchronious user. I suspect that if I had UNIX on
my system it would just cause an *increase* in the system overhead, because
I would not use enough of it to justify most of what it would supply me
with. I just don't have much need of forks and pipes (or even virtual memory
- I will be going to a 4-meg system soon, which will provide me with more than
enough memory for anything I'm likely to run on my system. UNIX would just
eat up more memory for page tables and system code than I would actually be
using most of the time!). I suspect that that is true of most users of
little systems.

I have used UNIX a little and have *not* liked it at all.  The documentation
tends to be poor and the error messages not very informative.  Unless MINIX
imporoves on this (along with some other changes) I probably won't bother
with it.  If I go for a more advanced O/S than CP/M-68K, I'll probably go to
OS9/68K or CDOS-68K (neither of which need a MMU).  I just as soon not spend
money for a MMU when I don't really need one.


		Robert Heller
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