Commodore 64 (C64) Preservation ProjectCommodore 64 (C64) Preservation Project
The "CYAN" loader
"CYAN" Protection Description

* This protection was disassembled, defeated, and documented by "Jani" in May, 2005.
* Copy protection author/originator is unknown, but it is used extensively on later European-released games by U.S. Gold, Sega, Mindscape, and Gremlin.
* We call it the "CYAN" loader because of the tell-tale way in which copies of these disks fail. The disk drive thrashes for a while, then the screen border turns to the CYAN color, followed by a system reset.

Although many of the games use different loaders (some fast, some not) all share a common copy protection check at boot that is located on track 5s5. The code is XOR'd many times, so decryption is a painful process.

There are two versions of the actual protection check- the older ones check for a signature on track 40s16, and the newer ones check for bad GCR on track 32s1. This latter version checks this a total of 8 times and clears the BAM in between each try, so the drive seeks back and forth across the disk making quite a menacing noise.

After the initial protection check is disabled, they do not check it again, so the disk can be copied cleanly and works in the emulators from a D64. Jani came up with a two-byte patch that defeats both versions of the protection completely.
This is done directly to an original disk converted to a D64:
offset 0x0592D 0xA2
offset 0x05935 0x0f

The disks can be remastered in unmodified form with the original bad GCR in place and play fine. They boot and play only on a PAL computer without any cartridges installed.

This project is all done in my own spare time with my own money. If you appreciate the amount of work that went into it, please donate whatever you see fit.
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All content copyright (c) 1971- by Peter Rittwage. All programs mentioned are copyrighted by their respective owners.