Date   : Thu, 01 May 2003 11:39:32 +0100
From   : Richard_Talbot-Watkins@...
Subject: Re: BBC Micro Games Copy Protection

Dave Moore <dllm@...> wrote:

> I've probably got about 20-or-so protected "bit copiers", but none of
> them work on a 1770 DFS.
>
> Were there any that did?

Those that I tried on my Master didn't work, but I understood the reason
for this to be that the 1770 DFS emulation of the 8271 "format track"
command corrupted memory (it had to build an image of the track in memory
before it could write it, and it just did this without a thought at the
start of user RAM, thereby trampling over code, data etc).  I had something
called Vector II which didn't work on a Master, but later versions of which
apparently *were* 1770 compatible, according to their ads in the back of
magazines anyway.

Rich
--
                                                                           
 Rich Talbot-Watkins                       Richard_Talbot-Watkins@...      
 Sony Computer Entertainment Europe              Direct line: 01223 341865 
 Cambridge Studio                                                          
                                                                           






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