Re: Copy Protection of PET cassettes - Flash Attack.

From: Daniel Kahlin <>
Date: Mon, 9 Aug 2010 14:47:38 +0200 (CEST)
Message-ID: <>
There are obviously many tricks you can use.
data left on the stack, data in zero page, state left in various 
I/O chips, etc...
I'm assuming it isn't too involved as you could find it in memory but 
perhaps this was after a reset?

I can have a look if you have an image of the disk.


On Mon, 9 Aug 2010, Bill Degnan wrote:

> While on the subject of copying assembler programs on the PET
> I have a copy of Flash Attack on disk that works and I can hook up two
> computers to play the game.  I can locate the program in memory but I have
> not been able to copy the program to cassette so I can run it on a really
> old PET.  I attempted to simply copy the memory location data into memory
> and dump to tape but this did not work.  I hunted around memory to try to
> find a missing bit or string of memory that must also be copied?  I know
> that this program used a copy-protection of some sort, but so far I have
> not been able to figure out how to move the program to cassette.  Anyone
> run into the same problem?  I noted what memory addresses change when the
> program has been run, but if there is a bit someplace to disallow the
> program to run  I can't find it.
> Here is a page I made about how to copy programs in mach lang from cassette
> to disk and back again for anyone here who does not have the how-to:
> Bill Degnan
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       Message was sent through the cbm-hackers mailing list
Received on 2010-08-09 13:00:34

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