> On Apr 13, 2022, at 8:12 PM, Fred Cisin via cctech <cctech@classiccmp.org>
> wrote:
>
> ...
> My mindset is/was still stuck in the disk format conversion realm, of trying
> to get information (hopefully information in the form of files, not just data
> as track images) from alien media.
> And, more often than not, unidirectionally.
Indeed. Though even that is hard for the more exotic formats, if original
controllers are unavailable. How would you read, for example, an IBM 1620 or
CDC 6600 disk pack, given that the machine is hard to find and those that
exists may not have the right controllers? But both are certainly doable with
a "generic" track extractor engine. Turning track waveforms into data then
becomes a matter of reverse engineering the encoding and constructing the
software to do that. This may be hard, or not so hard. For example, if you
wanted to do this for a CDC 844 disk pack (RP04/06 lookalike but with 322
12-bit word sectors) you'd get a lot of help from the fact that the source code
of the disk controller firmware, and the manual describing it, have been
preserved.
Then as you said the real goal is to recover files, which means also having to
reverse engineer the file system. That too may be documented adequately (it is
in the 6600 case, for example) or not so much (does such documentation, or the
OS source code, exists for the 1620 disk operating system?).
paul
