Path: utzoo!attcan!uunet!cbmvax!andy
From: andy@cbmvax.UUCP (Andy Finkel)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga software piracy
Message-ID: <5517@cbmvax.UUCP>
Date: 16 Dec 88 15:57:40 GMT
References: <27072@ucbvax.BERKELEY.EDU> <42600045@uicsrd.csrd.uiuc.edu> <2318@bucsb.UUCP>
Reply-To: andy@cbmvax.UUCP (Andy Finkel)
Organization: Commodore Technology, West Chester, PA
Lines: 31

In article <2318@bucsb.UUCP> crewman@bucsb.UUCP (Jerry J. Shekhel) writes:
>Absolutely true.  Cartridges are not any better than any of the other
>protection schemes.  In fact I believe there is no foolproof protection
>scheme.  The point is that somewhere in the program there is code which
>checks for the protection.  Disk-based software may have a bit of code
>that tests for the existence of some unreproducible media element, like
>an unusual track, etc., before allowing itself to be run.  Cartridge-based
>software often checks that its code cannot be modified (i.e., it is ROM)
>before continuing.  Find that bit of code, patch it out, and you've just

Way back when I did cartridge games, I hit on a method that would
allow a game to run *only* from cartridge (or write protected ram)...

All my tests on the static data structures of the game were done using the 
rotate instructions on the rom.  On the 6502, at least, the status flags and
carry were set properly, and the data structure was left unmodified.  If
you ran the game from ram, however, you'd end up with rather strange
results, as the game itself changed, depending on your actions.


Since, as a media, roms are pretty safe, I didn't feel bad about
it at all :-)
-- 
andy finkel		{uunet|rutgers|amiga}!cbmvax!andy
Commodore-Amiga, Inc.

"Possibly this is a new usage of the word 'compatible' with which
 I was previously unfamiliar"

Any expressed opinions are mine; but feel free to share.
I disclaim all responsibilities, all shapes, all sizes, all colors.