A funny protection by RG: Le prisonnier

[Antoine Vignau <antoine.vignau@laposte.net>]

Ah, Roland Gustafsson! A very good copy protection maker!

I like the one for "Le prisonnier", French version of "The prisoner", published by The Professor in 1983.

It is a DOS 3.3 with a change of markers and what is great is that the nibbles read in the header marker are used for the data marker.

Let's take an example:
TRACK 0:
D5 AA 96 FF FE AA AA AF AF FB EF (DF) (D5) (AD) FE FE FD FE
AB D5 AB D5 AB D5 AB
D5 AA AD xx xx

TRACK 2:
D4 AA D4 FF FE AB AA AA AE FB EF (DF) (AE) (AF) FE FE FE
FF AB D5 AB D5 AB D5 AB
AE AA AF

How does it work?
The RWTS reads the header markers either D5AA96 or D4AAD4
then the 4*4 volume nibbles
then the 4*4 track nibbles
then the 4*4 sector nibbles
then the checksum
then reads DF and records the two nibbles after it: AE AF in our example

And if you want to read the data, the RWTS routine checks for AE AA AF and then reads the data nibbles.

That's difficult to draw something on a text screen but I think you see what I mean.

I've never seen such a protection, any other titles? I believe Computerre or The Professor's other titles may have it.

antoine