Date   : Wed, 16 May 2001 10:30:48 
From   : "C Davies" <davies_@...>
Subject: Re: Locked and beyond

>From: "Rich Talbot-Watkins" <rich@...>
>Reply-To: "Rich Talbot-Watkins" <rich@...>
>To: "BBC Micro" <bbc-micro@...>
>Subject: Re: [BBC-Micro] Locked and beyond
>Date: Wed, 16 May 2001 09:47:26 +0100
>
>"C Davies" <davies_@...> wrote:
>
> > Anyone else remember the fun of cracking the protections on the trusty 
>BBC
> > games?  I used to have a passion for doing this to transfer stuff to 
>disc.
> > Programmers used to leave little messages embedded in the files that you
> > would unscramble on the way to cracking the games.
>
>Yep, it was always fun, and I've not come across anything quite the same on
>another platform since...

Absolutely.  It was just the sheer challenge that made it so much fun.  I 
think it was this, as much as anything else, that drove me on to become a 
games programmer.  I wouldn't be surprised if other people followed the same 
path into similar careers.

> > And the ultimate protections were by Kevin Edwards.  They certainly made
>you
> > think...  I remember he left his mailing address in one game, after 
>you'd
> > got through most of the layers of protection, asking for people who got
>that
> > far to get in touch with him.
>
>Kevin Edwards' protection systems always beat me unfortunately!  James 
>Fidell
>posted some code to this list a little while back which he wrote ages ago 
>to
>crack it - I was impressed.....
>

I had to resort to writing a basic program which emulated the processes of 
the 6502 for those.  As I remember, it had to be very accurate with the 
cycle timings as the code was scrambled based upon the VIA timers, so a 
single missing/extra clock cycle ruined the entire decoding.  And then, once 
the first page was unscrambled, it turned out that all it had decoded was 
more code to unscramble the rest of the game, again based on the VIA timers. 
  I got a good amount of respect for Kevin Edwards based on his protection 
code.

>Exile was nice too.... contained its own implementation of the filing 
>system
>commands (via vector interception) which allowed it to read its oddly
>formatted disc as if it were a normal DFS disc - but only if you'd hacked 
>thr
>ough the outer layers already!
>
>Can't think of any more at the moment... anyone else?

It's good to see that there are other people out there that spent more time 
cracking protections than actually playing the games :)

Regards,

Cliff

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