Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!NIC.GAC.EDU!scott
From: scott@NIC.GAC.EDU
Newsgroups: comp.sys.next
Subject: Mac emulator
Message-ID: <9010141624.AA06607@mcs-server.gac.edu>
Date: 14 Oct 90 16:24:48 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 44

aberno@questor.wimsey.bc.ca (Anthony Berno) writes:
>I gravely doubt if we will ever see a Mac emulator for the NeXT, for the
>same reason that there are no Mac clones. The Mac toolkit, for that
>matter the entire operating system, is entirely proprietary. 
>Furthermore, the way Mac toolbox calls are executed (direct ROM 
>addressing to the routines on the ROM chips) makes me doubt that it
>would be feasible. I know nothing about emulating other computers, but
>it seems to me that it would be especially difficult for the Mac
>even if you did know their secret ROM code and had a license to boot.
						      ^^^^^^^
>
>I may be wrong here, though... any feedback?

If someone had a license to use the Mac ROM code, Mac emulation would be
fairly trivial on the NeXT.  Then, we would have MacNeXT.

The reason I say trivial is because the Mac is really not that different
from a NeXT, you just toss in memory management.  There's no real support
for coprocessors on the Mac (I do not count the IWM, or any of that slime).
Reword that:  No real _requirement_ for coprocessors.  Thus, the essential
hardware of the NeXT is nearly identical.  Rewrite the display code to
look elsewhere in memory, and the io code to look elsewhere for disks and
printer, and you have a black, cubic Mac.

Of course, that's not that interesting, because you really want a NeXT
running Mac software.  That's where the memory management abilities of
the NeXT come in.  Just map the ROM code to wherever the Mac expects if
to reside, map out a page for the screen, and do some magic to get that
into a window, and you're very nearly done.  Most of the drivers (on
the Mac side) for everything are easy enough, because they've been done
for all the different hard drives and display adapters out there.

Now, what would _really_ be neat is to build in something to map the
window stuff in the Mac emulator to NeXT windows, menus to NeXT menus,
scrollbars to NeXT scrollbars . . . Then, you'd essentially have
a multitasking Mac/NeXT mutant, which would be even more amazing once
you added MacX . . .

scott hess
scott@gac.edu
Independent NeXT Developer	(Stuart)
NeXT Campus Consultant		(Not much, really)
GAC Undergrad			(Horrid.  Simply Horrid.  I mean the work!)
<I still speak for nobody>