Re: Commodore HSG Layout Disk Copy Protection

From: Ethan Dicks <ethan.dicks_at_gmail.com>
Date: Mon, 13 May 2019 14:44:22 -0500
Message-ID: <CAALmimmEzhUZQU3sBq2KhZ7aALZq_Aw7OzUWvTK-MQfneqUhyA_at_mail.gmail.com>
On Mon, May 13, 2019 at 2:24 PM didier derny <didier_at_aida.org> wrote:
> I saw a software, "silicon office", with a copy protection using a specific piece of code loaded in the 8050/8250 to read a specific track
> I dont remember exactly but they changed something in the format of this special track
> so if it was not read with their specific routine it failed or if the special track  was altered by a standard copy
>
> the code was quite short and put in place with memory write / memory read / memory execute
>
> I guess this system was used by several companies...

There are a number of copy protection tricks described (with example
code) for the 1541 in Chapter 7 of "Inside Commodore DOS"
(https://www.pagetable.com/docs/Inside%20Commodore%20DOS.pdf) but the
same general techniques, with slightly different implementations, hold
across any of the Commodore diskette drives.  Having their own CPU (or
two), these drives are insanely flexible.

-ethan
Received on 2020-05-29 21:20:14

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