'Track-to-track alignment'
Author:Lord Crass (guest: search)
Date: Tue, Apr 19th, 2011 @ 01:17 ( . )

Took another look at DiskBusters 2. It's a track-to-track synchronization protection.

V-Max loader is at track 1, then it immediately steps back to track 18, reads the sector 0 header, then steps to 19 and reads the first sector header that comes along. It then takes the sector number and adds it to the current track number, then steps to that track and does it again. It does this 4 times.

The final track number that you land on is used as a decryption key for some drive code that gets uploaded right before the copier starts.

The final track you need to land on for the correct key is track 30 (the key is $1e).

It probably doesn't match the original, but you could easily fix the image to pass the protection by rotating the 2nd last track it normally lands on (track 23 for the d64) so that sector 7 is the first sector it finds. You could even do this in a D64 and it will work.

Needless to say, this is one of those copiers that can't copy itself. What a ringing endorsement for its abilities...

Interestingly, the name Paul Rowe is mentioned in the code. This is likely the same Paul Rowe who co-wrote DiskMaker Plus (another one that couldn't copy itself) along with Mike Howard (who was also a programmer on the Maverick copier)

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