Software-based floppy disc data separator

[Kieron Wilkinson]

On 19 Jun 2010, at 02:22, Chuck Guzis wrote:
> I agree with Fred--format varieties number in the thousands.  There 
> are some that I haven't managed to crack yet (lack of Rosetta stone 
> mostly).  For example, how about extracting documents in Hebrew from 
> a Compugraphic typesetter floppy?

Yes, as I said to Fred, I think we have it easy in that regard because we are only dealing with personal computer formats, and are not doing file-level recovery. It is certainly the case that "secure" (verified) disk imaging is rather a different problem to meaningful information recovery. 

> What no one realizes is that "computers" in the sense of "personal 
> computers" are just the tip of the iceberg.  While they may represent 

Yes, I don't doubt that is the case. We are fortunate in that we don't tend to deal with file systems, and we don't deal with file formats. Dealing with personal computers means we can rely on emulators for that side of things. We're all about producing authentic disk images from the media into at least a form that is easier to backup (i.e. onto modern storage systems).

It's certainly nice to talk to people who do do that though! I don't envy you, but I'm sure it's interesting and gratifying work (?)

> the bulk of floppies in existence, they don't represent the variety 
> of variations in filesystems, encodings or layouts.  Most of the 
> details of those dedicated systems (say, from someone's PBX) remain 
> unknown to the current day.   There are some people lurking who have 
> knowledge of certain file formats (e.g. embroidery machines) who can 
> assist in translating the data to something meaningful.  But often, 
> the best you can get is "this is what the machine does when you feed 
> it this diskette".

Ouch.

> What complicates things even more is that very often, the equipment 
> that created these things no longer exists in any form.  You've got a 
> disk and maybe, if you're very lucky, a photo of the system or a 
> users' manual.
> 
> If anyone wants to try their hand at it, I can send a time-domain 
> (i.e. Catweasel) sample of a Lanier 32-sector M2FM (as best I can 
> determine it) WP disk.  You have only to figure out the character 
> set, file system, floppy encoding and file format...

Nasty. Might as well be a cryptanalysist for that sort of thing! I wonder if some statistical-based analysis would help, but perhaps you are way ahead of me on that?

Kieron