| Author: | Displacer (registered user: 14 posts ) |
|---|---|---|
| Date: | Sun, Jul 01st, 2012 @ 11:31 ( . ) |
Finally found the drive code and how it's loaded. After all the decryption of the main code, the drive code is there and in its decrypted state but you still can't see it. How it works is there are 2 blocks of $100 bytes that just look like random garbage. The code takes a byte from the first block, then it does some elaborate calculations on that byte involving all three registers, A, X, Y. When it's finished it comes up with an offset into the second block which is one byte of the drive code. It transmits that byte to the drive into the buffer at $300 and then starts again with the next byte. I think for completeness I may alter the drive code to read in track 2 in it's entirety into the extra drive ram I have to try and capture exactly whats there. I'll save that for another day though At any rate I think I now have the code and data for the protection in it's entirety and completely decrypted state, unless I run into any other little terrors like the drive code |
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