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From: CENT.MBECK%MIT-OZ@MIT-MC.ARPA
Newsgroups: net.micro
Subject: Re: SS vice DS disks
Message-ID: <14118@sri-arpa.UUCP>
Date: Tue, 29-Nov-83 08:26:26 EST
Article-I.D.: sri-arpa.14118
Posted: Tue Nov 29 08:26:26 1983
Date-Received: Fri, 2-Dec-83 07:07:49 EST
Lines: 23

From:  Mark Becker <CENT.MBECK%MIT-OZ@MIT-MC.ARPA>

     I've been following the messages regarding index holes in 8"
SS and DS disks.  And I'm somewhat confused. I've got a pair of
Shugart 851-R drives.  These drives have TWO index hole sensors,
mounted on the same circle that the index hole travels during
rotation.  The diskette jackets have a hole punched in them either
under one sensor or the other.  Looking at the schematics, I don't
see anything brought out to the PC card-edge that would indicate
to a controller what type of diskette was in the drive.


     Brian Kantor brings up the 'identity sector'.  My CP/M BIOS
does the same thing; identifies the type of diskette by some value
stored on the diskette.  This has a minor backfire if that byte ever
gets altered: you're going to have a problem reading the data off of
that diskette.

			---  Mark Becker


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