[stella] Perfect BIN copy protection

Subject: [stella] Perfect BIN copy protection
From: "Roger Williams" <mer02@xxxxxxxxxxxxx>
Date: Fri, 1 Feb 2002 21:33:09 -0800
----- Original Message ----- 
From: <cybergoth@xxxxxxxx>

> (BTW: For the other readers (Thomas already knows :-)) All of these 
> protection ideas started not because I think that protection is really 
> necessary, but because in another thread (in november?) someone
> said 'perfect protection can't be done' and I just have to proove 
> that wrong, (at least for 2600 BINs! :-))

OK.  Perfect protection can't be done.  Here's how to undo it:

You hook one bigass modern 2+GHz machine running DOS to
a hardware expansion card and monitor all the pins going to the
PROM on a real 2600 (or do the virtual same thing in emulation).

You have a semi-smart bit of software keeping track of the
whole 4K map as you play the game.   When the map changes
it starts recording a new copy and keeps track of writes done to
hardware in the intervals before the map changes.  4K is not a lot
of memory by today's standards and comparing the whole map on
a cycle by cycle basis is very do-able.

You will develop a finite number of maps.  "Finite" may be in the
tens of thousands, which is no problem what with hundred-MB
RAM and 100-GB hard drives being the norm.  You may even
have to write some fancy PERL script (I hear that's what people
do now that nobody does BASIC any more) to figure out what
triggers cause which maps to be switched in.  What with 2-GHz
processors, all those test loops will run to completion lickety-split.

Doing a PGP-like thing is not practical with the VCS's limited
processing capability, if you want it to actually play a game too.
I'd say that useful 2600 protection might have been possible
as late as 1990 or so.  But it isn't today.

You could, of course, compile into an emulator support for
some "extra" functions not possible in a real VCS.  That would
be akin to compiling in the necessary functions for "2600
DOOM" and saying it is a real 2600 game because it can
be played on a 2600 emulator.

Bottom line is, if you want to call it a 2600 game in any
real sense, you aren't gonna be able to copy protect it.


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