[comp.sys.atari.st] Spectre GCR / ST Disks

mike@mgc.uucp (Michael Blenkiron) (04/17/91)

I'm after technical details regarding the way in which Spectre GCR
(the superb ST Mac emulator) is able to read and write standard
Mac format disks using only the standard ST drive. I was under the
impression that Mac drives are variable speed, while PC/ST drives
use a fixed speed system. Of course, I may be very wrong about this.

Any information on the subject (as technical as you like) would
be greatly appreciated.

Chow,
Mike aka Baal the unsinkable.


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ytsuji@wucc.waseda.ac.jp (Y.Tsuji) (04/20/91)

You are right in saying that without additional hardware ATARI ST
cannot emulate a MAC. So, without a GCR controller board, one can 
import MAC files either via 1.44MB disks or via serial line.
mc68010 is slightly better than mc68000 in that it can restart a
bus error cycle( access to non-existent address -- usually an I/O
address --, a bus error, subroutine call to an emulator, restart).
But if the I/O address or ROM address overlaps, mc68010 is not the
right chip and moreover MAC is now an mc68030 machine, which cannot
be emulated by machines lacking an MMU. Therefore, if I were you,
I should be waiting till ATARI TT with a MAC-II emulator on its VME board
will become affordable for poor people. The mc68030 is ideal for emulation
because it can cope with the address overlap (all the additional
hardware can have convenient addresses).

I do wish a SUN emulator for TT to appear soon.

boyd@nu.cs.fsu.edu (Mickey Boyd) (04/24/91)

In article <5486@wucc.waseda.ac.jp>, ytsuji@wucc.waseda.ac.jp (Y.Tsuji) writes:
>You are right in saying that without additional hardware ATARI ST
>cannot emulate a MAC. 

Actually, there are several pirate versions of the Spectre, which load the 
mac OS from a disk image.  Dave Small goes to a lot of trouble to make this
difficult, but unfortunetely there are those that spend the time to do it 
anyway.  These pirate versions are totally disk based, requiring no hardware
whatsoever.  Of course, hardware is needed to emulate the group coded record 
disk format that the mac's use (hence GCR). 
--
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             Mickey R. Boyd          |  "Kirk to Enterprise.  All clear 
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chuckie@pro-odyssey.cts.com (Chuck Schul) (04/26/91)

In-Reply-To: message from boyd@nu.cs.fsu.edu

maybe they should do it on disk(like pddi...pcditto 1)would be a lot better
and would sell more!
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wilsona@dcs.glasgow.ac.uk (Alan Wilson) (04/29/91)

They cannot! Apple would descend upon them from a great height, since
the ROMS are copyrighted, and would require to be on each disc.

Alan Wilson


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