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From: korfhage%ucla-ats@sri-unix.UUCP
Newsgroups: net.micro.cpm
Subject: Function 37 - disk door open
Message-ID: <15659@sri-arpa.UUCP>
Date: Tue, 17-Jan-84 15:56:29 EST
Article-I.D.: sri-arpa.15659
Posted: Tue Jan 17 15:56:29 1984
Date-Received: Fri, 20-Jan-84 06:09:33 EST
Lines: 11

From:            Willard Korfhage <korfhage@ucla-ats>

   Floppy disk controller chips can check for an open door by monitoring
the sector hole sensor (the 1791 does this). If the chip doesn't receive
a pulse from the sensor within xx milliseconds of the last pulse, then it
knows the disk has stopped rotating, presumably because the door has been
opened. If I read the data sheet properly, the 1791 can send an interrupt
when this happens.
   This technique, of course, works for any floppy, regardless of size.

		Willard Korfhage