[vcf-midatlantic] Recovery of RD53 image data

David Gesswein djg at pdp8online.com
Tue Jan 25 18:11:28 UTC 2022

On Tue, Jan 25, 2022 at 10:32:11AM -0500, Ian Primus via vcf-midatlantic wrote:
> The most common problem with the RD53 drives is the rubber bumper stop
> that the heads rest against. 


> Which reminds me I have another one sitting here I need to do recovery
> on as it is... From there you can use David Gesswein's wonderful MFM
> emulator to image the disk.

Biggest problem is RQDX3 does translation of the drive sector mapping to
hide bad sectors and the data tables it uses. Not sure about the earlier
controllers.  My emulator can recover whats really on the disk but additional 
software needs to be written to unravel to sector mapping to get an image 
usable by SIMH. I haven't had the time/incentive.

Need to find out what controller the drive was used with.

> TK50's are notoriously unreliable, some of them are starting to shed,
> and many of the drives are broken or incredibly flakey. That said,
> it's possible to recover them, I have a SCSI TK50 drive that I've used
> for both recovery and for creating bootable tapes, although I haven't
> used it in years. Been a while since I had to try to use TK50 tapes.

I have a bunch of tapes on the to read stack. I think I got the drive
working but was running into the tape sticking problem. On the todo is
buying/making a tape baker to try to archive the tapes. I also got a SCSI
version of the drive which should make it easier to create an image.

Freeing the heads and reading the drive wouldn't take too long assuming drive
behaves. Making a usable SIMH image would take time. Someone with a easy
way of making a disk image with the appropriate DEC hardware would likely
be easier. Reading the tapes would also take a larger chunk of time.

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