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From: dclemans@mntgfx.mentor.com (Dave Clemans)
Newsgroups: comp.sys.atari.st
Subject: Re: high density 3.5" disks
Message-ID: <1987Nov10.141529.2161@mntgfx.mentor.com>
Date: Tue, 10-Nov-87 17:15:27 EST
Article-I.D.: mntgfx.1987Nov10.141529.2161
Posted: Tue Nov 10 17:15:27 1987
Date-Received: Fri, 13-Nov-87 07:22:07 EST
References: <2923@hcr.UUCP>
Organization: Mentor Graphics Corporation, Beaverton Oregon
Lines: 20

The difference between the current ST floppies and the 2 megabyte
ones is similar to the difference between the floppies on an
IBM PC-XT and a IBM PC-AT.  Basically the clock rate is doubled,
letting you pack in twice as much information.

The consensus among the hardware people I've talked to is that
the WD 1772 that's currently in the ST can't handle a higher
clock rate.  However if you removed the 1772 from the motherboard
and replaced it with a daughter board with appropriate clocks,
controllers, etc.  you could get the hardware set up correctly.

The software incompatibilities you'd see would include:

    the desktop disk formatter and copier probably wouldn't work
    (but there are public domain versions of both of these available)

    nothing knows about "switching" densities; i.e. you'd have to
    invent some way to dynamically change clock rates

dgc