Audio Cassette formats; Copy protection?

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Mon Nov 30 11:10:22 1998

>> Someone mentioned that there are copy protection schemes for cassette
tape,
>> and I was curious what these might be and how they might interfere with
>> recording the tape onto my HD.
>
> Some machines (the BBC micro is one IIRC) have a bit in the cassette
> block header that when set prevents you listing or saving the BASIC
> program. That's one trivial form of copy protection.
I don't recall that one on the BBC. You could do that on the ZX81 due to
very strange operating system features.

The BBC had a header on each tape _block_ that said where the file would be
stored in memory, how long it was and an execution address. One simple
scheme rested on the fact that the parameters the machine used were taken
from the first block of the file and those it told the user were taken from
the last block...

I also saw a program which, when listed or saved, gave "bad program", but
would run OK. Don't know how that was done...

Philip.
Received on Mon Nov 30 1998 - 11:10:22 GMT