Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!murtoa.cs.mu.oz.au!ditmela!latcs1!stephens
From: stephens@latcs1.oz.au (Philip J Stephens)
Newsgroups: comp.sys.apple2
Subject: Re: System programming for the Apple II (preferably the IIe)
Message-ID: <7368@latcs1.oz.au>
Date: 6 Mar 90 05:18:44 GMT
References: <6673@hydra.gatech.EDU>
Organization: Comp Sci, La Trobe Uni, Australia
Lines: 32

COOOOoooooOOOoooOOOKIE!!!! writes:
> 
> Lately I've been wondering about a few things:
> 
>     Considering there are C compilers (well, at least one) for the Apple II,
>how possible is it to write the "assembly only" sections of unix, and then 
>compile the C sources for unix on a Apple II?  I know it would require some
>of the heavy dute memory expansions that AE makes for the apple II, but still..
>I'm still using apple dos 3.3...I don't think I'd be terribly upset at having
>to buy a large chunk of memory for my machine..
>
>John

   Nice thought, but pretty much inpractical.
   First of all, remember that Unix is multitasking, whereas the Apple IIe is
not!  You'd have to modify the C sources quite drastically to get a single
user version capable of running on an Apple.  Either that, or get your hands
on one that isn't multitasking.
   The same problems exist for implementing the virtual memory system, paging
faults, disk I/O handling etc.  Basically, what I'm trying to get at is you
can't port over a standard version of Unix from a Pyramid, Mips or Vax.
   Someone has already mentioned the security aspects as well, which relates
back to what ought to happen when a program crashes.  Unix expects to regain
control in situations like this, but on an Apple that is not always possible!
Put simply, the 6502 (and the Apple in general) couldn't cope with anything
but a diluted version of Unix; and in that case, you'd be better off re-writing
the C sources yourself!

   Actually, writing a single user version of Unix from "scratch" wouldn't be
that bad; if you're into that sort of thing...I would think that a basic
version wouldn't be any more complex than DOS or ProDOS.  I wouldn't mind
attempting it if I had the time ;-)