| Author: | Hyperactive (guest: search) |
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| Date: | Thu, May 23rd, 2013 @ 00:37 ( . ) |
Hello there Can anyone investigate weather power at sea and Grand Prix Circuit are truly protected? If I convert to d64 instead of g64, the games still work. I suspect but can't say for certain the protection have been patched out using maverick or something similar. I have a flux dump of Grand Prix Circuit which I'll test later today. Cheers. |
 | Author: | Sncboom2k (registered user: 1 posts ) |
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| Date: | Fri, Jun 07th, 2013 @ 02:30 ( . ) |
Where did you get the G64's? Are they originals of yours or downloaded dumps? |
 | Author: | Markus Benko (registered user: 16 posts ) |
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| Date: | Mon, Dec 16th, 2013 @ 09:48 ( . ) |
While not having disassembled the drive code, I think that the protection used on these titles measures the sector gaps on track 21 and expect the lengths to be equal or does some other uniformity check. When the track is written at once like it is done with professional duplication equipment, all gaps are exactly the same unless instructed otherwise. But this is normally not the case when doing a sector-wise disk copy using the 1541, i.e. without RAM expansion or special hardware. Due to drive speed variation there will always be a few bits more or less in every gap. My guess is that when an emulator internally generates the raw track data from the D64 user data it also will generate uniform gaps, which makes the game run smoothly from a D64 file. This doesn't necessarily apply to all emulators and all versions of them, perhaps an earlier VICE version did not do it that way. |
| Author: | Markus Benko (registered user: 16 posts ) |
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| Date: | Mon, Dec 16th, 2013 @ 10:37 ( . ) |
Didn't think about the obvious: Somebody could try this on standard CBM hardware using a standard disk copy program. -> It shouldn't work. But if you format a disk and copy all tracks -except- track 21 it actually should work. I'm unable to test this on my own because I have not setup my C64 system yet. |