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From: bryce@COGSCI.BERKELEY.EDU
Newsgroups: comp.sys.mac
Subject: Disk Format
Message-ID: <8705150534.AA04539@cogsci.berkeley.edu>
Date: Fri, 15-May-87 01:34:55 EDT
Article-I.D.: cogsci.8705150534.AA04539
Posted: Fri May 15 01:34:55 1987
Date-Received: Sat, 16-May-87 14:08:32 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 18

I know a little bit about the Macintosh disk format, but would like to know
more.  What I think I know follows.  Would anyone care add to it?

1> GCR format compatible with the 6 & 2 scheme used by Apple ][  DOS 3.3.

2> Varriable rotational speed.	Slower on the outside.	Speed value read
   during (near) horizontal retrace from the sound buffer.  A scope pegs
   the rotation at 350-600 RPM, but factory spec speeds would be of
   interrest.

3> Since I have never been significantly close to a Mac SE what follows is
   based on rumor:  The SE drive spins at a constant speed and the
   electronics sort out the difference.  This would require a change to the
   IWM chip.  I apologize if I missed the Tech Note.


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