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From: frans@philmds.UUCP (Frans Meulenbroeks)
Newsgroups: comp.sys.atari.st
Subject: Re: (pc-DITTO and the) Magic Sac
Message-ID: <349@philmds.UUCP>
Date: Wed, 12-Aug-87 03:31:32 EDT
Article-I.D.: philmds.349
Posted: Wed Aug 12 03:31:32 1987
Date-Received: Fri, 14-Aug-87 01:46:24 EDT
References: <17680@cca.CCA.COM> <979@eneevax.UUCP>
Reply-To: frans@philmds.UUCP (Frans Meulenbroeks)
Distribution: world
Organization: Philips I&E DTS Eindhoven
Lines: 29
Keywords: Mac-emulation

In article <2619@ur-tut.UUCP> mcli@tut.cc.rochester.edu.UUCP (Maurice Ling) writes:
>
>In the last newsletter from Data Pacific, it did not give any price for the
>Mac Disk drive transformer.  It did say that it was a box that would attach
>to the ST and disk drive and it would automatically switch back and forth
>between ST and Mac "modes".  It would also work with the internal drive
>on the 1040ST.  Sounds really neat...

Mmmm. I'm sure ding doing these things with the internal drive of the 1040
requires some rerouting of wires or replacement of chips with connectors.
An external drive would be a lot easier.

The "trick" I would use is the following:
a small hardware device which can toggle the motor on line of the
floppy with various duty cycles and a not too low frequency.
If you choose your frequency not too low there is no problem.
Otherwise speed irregularities could occur.
Upon bootup set the device off. The Mac system could turn the device
on before attempting a floppy transfer. Of course the duty cycle 
varies with the track needed! Some investigation/experimentation is
required here.
One restriction: The ST's nominal speed (300 rpm) must be >= than
the maximum speed achieved in a mac.

Disclaimer: I have no Sac and hardly any Mac knowledge.
-- 
Frans Meulenbroeks
	Philips Distributed Realtime Multiprocessor System
	   uucp: for the time being: philmds!frans