I wrote about formatting TU58 tapes:
I think it would be easier to use the same [stadard
TU58) electronics.
The only issue is that I think a small modification might be necessary
to produce the "mark" waveforms used at BOT, EOT, and in IRGs. If
that does prove to be necessary, it should be a very minor addition,
and shouldn't affect normal operation of the drive.
After further study, I'm fairly certain that no hardware modification
would be required.
Does anyone have a new (unused) blank TU58 cartridge that they'd be
willing to make available for research? The tech manual doesn't give
quite enough detail of the tape format, and reverse-engineering the
firmware won't reveal certain aspects such as the lenghts of the gaps.
A pristine factory-formatted tape would be the most reliable source of
that information. Once the tape has been written in the field, the
resulting gap lenghts may vary.
Eric