TU58 tape formatter (was Re: rebuilding DC100A cartridges?)

[allison]

On 11/13/2018 03:46 PM, Ethan Dicks via cctalk wrote:
> On Sat, Nov 24, 2012 at 4:08 AM Eric Smith <eric at brouhaha.com> wrote:
>>> It is remotely possible that there's an undocumented "format" command
>>> in the protocol.  However, I've heard multiple people claim that
>>> special firmware was required.
>> I spent some time reverse-engineering the firmware.  There is only one
>> undocumented opcode, decimal 10, and I haven't yet figured out what it
>> does, but it definitely doesn't format a tape.
> Is Opcode #10 the "Enter MRSP Mode" or is that something else?
>
> -ethan
Same here,

I asked while I was at DEC and the designer said need a special rig to
do that and the important
things was EOT and BOToptical sensors and the code with the basic
patterns.  The TU58 does not
have an EOT or BOT sensor as it detects end marks on the tape.

I think using disassembled code and adding the sensors its possible to
put down the marks needed.
Never explored it fully to prove that.  It was easier to make a
RAM-based TU58 work alike and at
least one company did a floppy based TU58 work alike.

Allison