Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!glenn
From: glenn@cs.utexas.edu (Gwangwu Lai)
Newsgroups: comp.sys.ibm.pc
Subject: Floppy drive
Message-ID: <145@megalon.cs.utexas.edu>
Date: 6 Mar 90 20:53:37 GMT
Organization: U. Texas CS Dept., Austin, Texas
Lines: 21


*jlb@aipna.ed.ac.uk (John Beaven) said:
*
*John> If I start up the machine and do DIR B:, I get the contents of
*John> drive B: as expected. If I then change the floppy in drive b:,
*John> and do DIR B: again, I still get the contents of the first
*John> floppy, even though the light on the drive goes on and it looks
*John> as if the machine is reading it. ...
*
*This is a long shot, but do you have either of the floppies in
*question write-protected?  I've had similar bizarre happenings like
*that on an AT and that was why.  Don't understand why, so don't have
*an answer...

The answer is that a DC (Disk Change) signal tells the controller if
a new disk has been inserted into the drive.  If this signal is somewhat
screwed up, you end up with the symptom described above.  Do a CTRL-C
when you change disks; that should fix the problem (albeit a lousy fix).


Glenn