Re: 800KB DD disk reliability in SuperDrives?

[Warren Ernst <wernst@gmail.com>]

On Feb 5, 12:25 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Warren Ernst wrote:
> > 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?
>
> ISTR that there was a format failure mode that occurred when a
> Superdisk controller was used to format a PC-formatted disk in a
> Superdrive without first doing a "read"...
>
> I'm not sure that applies to your case, but here's the reference:
>
> http://groups.google.com/group/comp.sys.apple2/msg/945863e9f1acb86c
>
> -michael
>
> NadaPong: Network game demo for Apple II computers!
> Home page:  http://members.aol.com/MJMahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."

Ah yes, I remember that bug. I don't think it applies here though,
since I can format an 800KB ProDOS disk in a regular Apple 3.5" drive
first, verify it there, and THEN let the SuperDrive try to format it
and I get the error.

-Warr