SE/30 odd behavior - test-drb@ccmp.vtda.org

17 Sep 2002

At 01:00 AM 9/17/02 -0400, you wrote:
...
 On Tue, 17 Sep 2002, Carlos Murillo wrote:
  The machine thinks that there is a floppy disk in
the superdrive
 constantly; it is always trying to read the (empty) drive,
 then the "This disk cannot be read; Initialize? Eject?" dialog
 box shows up, I click on "eject" and it starts trying to
 read the nonexistent floppy again. Something fried the disk controller. I did this
to one of my SE/30s once
by being cavalier about not shutting the machine off before connecting and
disconnecting an external disk drive. 
Ouch, I really hope that this is not the case;  SE30's are rare
here in Colombia.  I know that I haven't plugged an external floppy
to this machine in eons. So if it is fried, that came out of the blue.

I did another experiment: I unplugged the floppy ribbon cable and
turned the computer on.  No more "...initialize or eject" dialogs.

I've been looking at the SE30 schematics
(http://www.archaic-apples.com/index.php?category=Macintosh&subcategory=…
matics),
especially page 2 of the SCSI-SWIM diagrams, where the floppy
disk controller is depicted.  I see that the RDDATA line in the
header is tied to the RDDATA _and_ SENSE pins in the controller
chip.  I don't see any signal name other than "SENSE" that might
indicate if there is media in the drive.  I also see that
all of the lines go through an "RCNET" pack before heading out
to the external floppy disk connector.  I wonder if the problem
might be in this device... I'd like to wait for input from you
guys before I turn on the soldering iron.

...
 I suppose it goes without saying that the floppy
controller is not a
standard part. 
Not socketed, either :-( .

carlos.

--------------------------------------------------------------
Carlos E. Murillo-Sanchez   carlos_murillo(a)nospammers.ieee.org