Re: SpiraDisc Prolog Address

[Andy McFadden <fadden@fadden.com>]

Michael J. Mahon <mjmahon@aol.com> wrote:
>>    How do privacy know to crack original disk by reading RAM.  All Apple
>>II+ and later models have vector reset that prevents us from reading RAM
>>when vector reset erases whole RAM.  We have to use original monitor without
>>using AutoStart ROM that we can be able to read RAM without using vector
>>reset.
> 
> Actually, all models prior to the //e do not seriously damage RAM
> contents upon reset.
> 
> The desire to capture all of RAM unaltered (by, for example, the text
> screen scrolling) is what led to the rise of IRQ cards like the WildCard.

Another alternative: there was a hack to add a write-protect switch to
a language card.  You could, in effect, replace the ROMs with something
that would save off the fragile areas (0x200-2ff, 0x400-7ff) by replacing
the vector at fffc.

>>    It is my concern that some copy-protected games fail while playing.  For
>>example, the players go to the high level from low level.  It will fail to
>>load high level game.  I suspect that privacy takes unused sectors from
>>track to track by putting privacy picture there.  The privacy picture might
>>overwrite important data that high level is trying to read.  Does it make
>>sense?

I believe Dungeon Master GS had independent copy protection checks at
each level of the dungeon.  This led to a number of not-quite-working
cracked versions of Dungeon Master.

- Andy

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