TurboDOS 7.1 Preservation / dumping - help needed

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Joined: Wed Oct 16, 2019 4:51 pm

TurboDOS 7.1 Preservation / dumping - help needed

Post by toshi »

Dear all!
I recently bought a kryoflux with the target to archive a original set of TurboDos 7.1 diskettes (maybe the last copy on earth which survived, who knows).

I assume that kryoflux does not know the disk format of Turbo-DOS.

I have from an other source some infos on the disk format
BEGIN P35 Philips P3500/3800 DSDD 96 tpi 5.25" 640KB




SECTORS 16,256

SIDE1 0 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16

SIDE2 1 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16

BSH 4 BLM 15 EXM 0 DSM 319 DRM 255 AL0 0F0H AL1 0 OFS 0

In addition, I do not want to try 100x of times several setting until it works. I am not sure how good the disks are (I have no running P3800 machine yet!), so I want to do everything right when I start with the preservation process. Maybe I have only one read until the media fails?

I am totally new to kryoflux, so maybe sombody could give me an advice how to start?

I have two wishes:

- Duplicate the disks
- If possible, create a binary image which I can process on my pc (e.g. extract files).

Thank you all

Posts: 288
Joined: Fri Nov 08, 2013 10:48 pm

Re: TurboDOS 7.1 Preservation / dumping - help needed

Post by brightcaster »

Please do a "kryoflux stream files" (raw) dump first. After that you may work with that raw stream data files rather than tempting the original floppies again and again.

In the end you may decode to general "mfm sector image". If you want to get the files of the images cpmtools should do the trick...


Posts: 269
Joined: Wed Feb 18, 2015 8:18 pm

Re: TurboDOS 7.1 Preservation / dumping - help needed

Post by SomeGuy »

First thing, inspect the surface of the disks and make sure they are clean and in OK condition before inserting in to a drive.

If these are low (double) density 96 TPI disks, you will need to dump them using a "1.2mb" IBM PC style drive. When dumping make sure the kryoflux density line option is set to "high" (which means low density). Since these are 96tpi media, tell the Kryoflux to dump 80 tracks.

Start with the "Preservation Stream" type, which records the raw flux signal from the disk. You can feed that back in to the kryoflux software or other analysis tools to decode it later.

This will not check for bad sectors, but if the format is not what is expected, it will not have to sit and spin while you try to figure it out.

If the disk starts falling apart, the flux stream dump will contain everything possible from the first read attempt, giving the best possibility of reconstructing any damaged data.

If you are lucky, decoding the stream afterwards as "MFM" will decode all sectors. (Ignore any "H" header warnings if these are not factory mastered disks).

If decoding does show errors, you might first try decoding with other tools such as HxC (decoding results can differ) or posting them here, but then try re-inspecting/cleaning the disks and dumping again, using either more stream files or MFM image if you want automatic retrying.

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