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From: logajan@ns.network.com (John Logajan)
Newsgroups: comp.sys.atari.st
Subject: floppy disk-change (again)
Message-ID: <1990Mar24.192858.1655@ns.network.com>
Date: 24 Mar 90 19:28:58 GMT
Sender: news@ns.network.com
Organization: Network Systems Corp., Mpls., MN
Lines: 20

From time to time I've seen mention of replacement floppy drives not indicating
disk change status.  Since I've had a replacement drive for longer than my
human memory works, I don't recall if the original could really detect disk
change status either.

Looking at the pinouts and schematics for a 520 ST reveals that there is
no dedicated "disk change" signal.  So if the original Atari floppy drives
could inform of disk change condition, that information would HAVE to be
indicated in some way over the only lines available to do so, namely:
read-data, track-0, write-protect, and index.   Furthermore, these signals
go directly and only to the floppy controller chip, so that if there is
any disk-change detection going on, it has to be occuring there.

I will pursue this by looking into the specs of the floppy controller,
but if anyone has any clues or knows the answer to this, let me know.
Thanks.

-- 
- John Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428
- logajan@ns.network.com, john@logajan.mn.org, 612-424-4888, Fax 424-2853