Re: 800KB DD disk reliability in SuperDrives?

["geoff" <geoff@a2central.com.remove-12cr-this>]

  To: Warren Ernst
Let me try this again.

It is not unusual to have 800K disks not format on a SuperDrive, but format 
correctly on the Apple 3.5.  It is also not unusual to have perfectly fine 
800k not be readable/writable by SuperDrives.  I recommend to use only 800k on 
the low density drive and only 1.4 megs disks on the high density drives.

Geoff


 > All,

 > I'm starting to come to the conclusion that High Density SuperDrives 
 > (connected to a SuperDrive Controller, of course) do not reliably
 > format 800KB Double Density 3.5" disks. I wonder if anyone can confirm
 > or deny this in their personal experience.

 > Here's my evidence.I have the following hardware:

 > A ROM3 GS with a SuperDrive Controller, two SuperDrives, and one
 > "regular" Apple 3.5" Drive.

 > An enhanced Apple //e with a Liron card and two UniDisk 3.5" drives.

 > A Windows PC with a known-good 3.5" drive. I have a formatting tool
 > that manually verifies every block to weed out bad disks.

 > A few jillion old HD and DD 3.5" disks.

 > I can format the same HD 3.5" disks under Windows or ProDOS (Copy II
 > +) and then run a Disk Verify tool and they all come up with no
 > errors. I can format it MSDOS and then verify it good, then reformat
 > it ProDOS and verify it good with every SuperDrive I have. HD disks
 > that fail verification on one machine fail it on another machine.

 > Similarly, I can format 800KB DD disks, and verify them, with the
 > Apple 3.5" Drive on the GS and on both UniDisk 3.5" drives, and then 
 > reverse the disks with the machines and verify them again. Disks that
 > fail verification on one drive will fail it on another drive.

 > Finally, if I take a verified-good 800KB DD 3.5" disk and attempt to format 
 > it in a SuperDrive (as an 800KB disk, of course), the format invariably 
 > fails with a block error. This happens with both my SuperDrives. I can then 
 > reformat the "bad" disk with the Apple 3.5"
 > drive and test it, and it verifies fine.

 > The SuperDrives can *READ FROM* the 800KB disks without any problems.
 > They will do a Disk Verify operation on 800KB disks without problems 
 > either. They seem to write files to the disks just fine too. They just 
 > can't seem to format them properly.

 > Does this jive with anyone else's experience?

 > -Warr

 > --- Synchronet 3.14a-Win32 NewsLink 1.85
--- Synchronet 3.14a-Win32 NewsLink 1.85
A2Central.com - Your total source for Apple II computing.