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From: grunau_b@husc4.harvard.edu (justin grunau)
Newsgroups: comp.sys.atari.st
Subject: Re: software Mac and rudeness
Message-ID: <920@husc6.UUCP>
Date: Thu, 18-Dec-86 16:38:27 EST
Article-I.D.: husc6.920
Posted: Thu Dec 18 16:38:27 1986
Date-Received: Fri, 19-Dec-86 00:24:56 EST
References: <8612181103.AA02378@ucbvax.Berkeley.EDU>
Sender: news@husc6.UUCP
Reply-To: grunau_b@husc4.UUCP (justin grunau)
Organization: Harvard Science Center
Lines: 53


I agree 100% with MARKS-ROGER@YALE.ARPA on his response to Patrick@ark
(Paul Molenaar?) regarding the Magic Sac and this alleged "new European
emulator".  It was offensive to imply that David Small is trying to boost
his profits by using hardware instead of software;  it is, however, probably
based on a gross misunderstanding.

In no rational sense can David Small's cartridge be called a "hardware
emulator".  The cartridge itself does not contain any of the emulation ware
at all -- the emulation, if you can call it that, is done by software that
you get on a little TOS diskette.

A good example of a hardware emulator is Atari's upcoming Big Blue Box:  they
use hardware (an 8088, amongst many other things) to convince the MS-DOS
software that it is running on an MS-DOS machine.  The better the emulator,
the closer the software actually IS to running on an MS-DOS machine:  the
MacCharlie emulator is supposed to be an IBM clone without the keyboard and
screen.

A good example of a software emulator is Paradox's MS.EM. -- it is software that
runs on the 68000 that emulates the hardware activities that an 8088 would
perform:  in other words, it is just an 808X instruction set interpreter, no
different in principle from a BASIC interpreter.  I think we can rule this
definition of software emulation out for the European Mac emulator:  it would
be foolish (and very slow) to write a 68000 interpreter that would run on a
68000.

In any event, the Magic Sac is neither version of emulator, least of all a
hardware emulator, because you have the most relevant piece of hardware there
already:  the 68000!  The only emulation ware he sells you is his set of
patches to the MacIntosh OS that re-route hardware references to the ST
hardware, which is of course quite different from the Mac's.  Any software
that bypasses calls to the OS and directly references hardware will of course
fail miserably on the Magic Sac, and unfortunately more applications do that
than we would like.  The ROM cartridge isn't really "hardware emulation" --
it's just a legal way to get the SOFTWARE contained in the Apple ROMs into
your machine.  Copying the contents of the ROMs onto disk and selling them would
be highly illegal, and I doubt the Europeans are doing that.  Also, it is hard
to see an advantage to loading the ROM software into your RAM -- if you use the
cartridge, you don't use up any RAM, which is a clear advantage!

Now that we have cleared this up, perhaps the original note writer would like
to elaborate on his report, and/or direct us to the original sources?  I would
speculate that if the European approach is truly different, it must be a
rewrite of the Apple ROMs (a la Phoenix's version of the IBM BIOS).  It is
hard to see offhand how this would be any better than using the real ROMs --
here, too, I would expect that applications which directly access hardware
would fail, and I don't think it would be cheaper to develop such a product
than what David Small has done ...

									JJMG

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