Subject: Re: Running macbsd on LCIII
To: None <>
From: Brian Kendig <>
List: macbsd-general
Date: 12/16/1993 13:14:31
>I'd like to get to the point, soon, that we can run on all '020+MMU and
>'030 Macs...  We'll see how realistic that is...

Yay!  Maybe finally there will be something good to be said for my mistake
of buying a IIvx three months before the Centris 650 came out.  ;)

Out of idle curiosity, though, I've got a few questions:

(1) Wouldn't it be easier to make a version of MacBSD that runs on *top* of
the Mac OS?  There's already a commercial Unix for the Mac that does this;
wouldn't it make life a heckuvalot easier to use Mac filesystem calls
instead of rewriting the file system from scratch, and to use all the
normal toolbox graphics calls instead of rewriting graphics from scratch?
An application that let me roam my Mac with a tcsh, run Unix shell scripts,
open multiple shell windows, and multitask between then within the
application would be very handy indeed -- even better than a full-blown
replacement operating system in some ways, because there wouldn't be any
need to worry about being able to run normal Mac software too.

I have the feeling that the answer will be "no, it wouldn't be easier" --
why not?  Inquiring minds want to know.  ;)  I have the feeling that I'm
missing an obvious point here.  What's the reason that MacBSD is being
written to replace the Mac OS, instead of running on top of it?

(2) What's keeping MacBSD from being able to run on old 68000 Macs?  I know
my SE doesn't have a PMMU and therefore it can't handle virtual memory, but
is there a reason that the Unix kernel needs to have access to virtual
memory?  Is there anything preventing a "MacBSD Lite" (for SE/Plus and
earlier) from theoretically someday becoming available, or are there
serious hardware issues that completely preclude that possibility?  (No,
I'm not seriously interested in ever getting Unix to run on my SE; I'm just
curious about the "magic powers" of a PMMU and why it seems to be so critical.)

_/_/_/  Brian Kendig                              Je ne suis fait comme aucun
/_/_/                 de ceux que j'ai vus; j'ose croire
_/_/                             n'etre fait comme aucun de ceux qui existent.
  /  Be insatiably curious.   Si je ne vaux pas mieux, au moins je suis autre.
 /     Ask "why" a lot.                                           -- Rousseau