unreadable HP cartridges

[Tony Duell]

>    I still have a bottle of it but what good would it do to know the binary
> pattern? You couldn't program a new tape with it.

Maybe not with the standard HP controller , but you could, surely, send
pulses with the right spacing to a tape drive to recreate the pattern on 
a new tape.

[1] Although I think you could with an HP9877 or a 9825 running special
software, since those controllers are very dumb devices, they don't even
do any form of serial-parallel conversion. I am not so sure about the 
9845 controller, it's got an HP custom bybrid in the middle with 64 pins. 
Many of them go straight to the I/O bus, the rest go to the tape drive, 
amplified read signal, etc. All the interesting stuff is inside that 
hybrid...

-tony