Date   : Thu, 10 Aug 2000 23:27:58 +0100
From   : James Fidell <james@...>
Subject: Re: More tape to disc transfer fun: Alien 8

Quoting Rich Talbot-Watkins (Richard_Watkins@...):
> James Fidell <james@...> wrote:
> 
> > Quoting Rich Talbot-Watkins (Richard_Watkins@...):
> >
> > > While we're on this tape to disc thread (Hampstead), here's my chance
> > > to bring up an old favourite topic of mine: did anyone ever look at
> > > Kevin Edwards' EVIL protection on Alien 8 by Ultimate, and did anyone
> > > crack it and get it onto disc?  My conclusion was that it was actually
> > > impossible to crack without writing a hardware emulator or resorting
> > > to hardware cheating somehow.
> > >
> > > Anyone who ever looked at the code will know exactly what I'm talking
> > > about!
> >
> > Sure I did.  And yes, I wrote some hardware emulation to do it :)
> 
> Ahhhhh.... I'm impressed!  And quite intrigued as to how you figured it all
> out.  I never got the timings right for certain things so it never stood a
> chance of working.  How did you figure out the exact behaviour of something
> like ROL &FE65 anyway?

Hmmm, I'm not really sure, to be honest -- it was quite some time ago.  I
was probably only 14 or 15 and so had plenty of time on my hands to for
the trial and error method.  I seem to recall that there was one section
of code which decoded another.  That second section decoded the main program
using a similar method to the first decoder.  I basically worked on just
getting to the point where the first decoder produced something that looked
like a viable program for the second decoder, after which I'd learnt
enough to do the second stage quite easily.

I've even just discovered that I still have the code I wrote to do it :)
It's all of 5k of assembler source.

James.
-- 
 "Yield to temptation --             | Consultancy: james@...          
  it may not pass your way again"    | http://www.cloud9.co.uk/james
                                     |
        - Lazarus Long               |              James Fidell