Path: utzoo!attcan!uunet!mcvax!hp4nl!botter!tjalk.cs.vu.nl!jcvw
From: jcvw@tjalk.cs.vu.nl (Winkel van J C)
Newsgroups: comp.os.minix
Subject: Re: 68K minix
Message-ID: <1963@botter.cs.vu.nl>
Date: 2 Nov 88 09:05:01 GMT
References: <5089@louie.udel.EDU> <1600@ast.cs.vu.nl>
Sender: news@cs.vu.nl
Reply-To: jcvw@cs.vu.nl ()
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 12

The Apple Macintosh does not use the 'standard' disk recording techniques
(MFM or double density). The technique used is called 'Group Coded Recording'.
Technically it is possible for the Mac to read MFM discs because in the Mac
the 68000 does almost all disc reads/writes by itself and a special Apple-made
chip called the IWM (Incredible Woz Machine, after Steve Wozniac, its creator).
This scheme also allows to use different rotational speeds for different 
cylinders of the disk, thus gaining storage capacity.

Therefor a 'standard' disk device driver cannot read a atari disk. A Mac 
version of readfs would have to include a special device driver to read MFM 
disks, not an easy task...
Jan Christiaan van Winkel