This will create a complete track of "weak bits" that are entirely unreadable by a normal FDC - Unfortunately, a software pirate can reproduce the same thing with a standard floppy disk controller by simply not formatting that track on his copied disk as well - So, this is maybe too simple. You can simply generate such weak areas by not formatting a specific track (or part of that track) on the disk at all. While this might theoretically be possible (aging disks that can be read successfully after several re-tries seem to prove this), I very much doubt this could be reliably reproduced in mass-production of disks. The apparently common conception that this would be done with "weak magnetization" or a change in magnetic flux that is "smaller" than normal, is wrong. ![]() Obviously, that check needs to be well hidden in the software, otherwise, it could easily be deactivated by malicious people. The copy protection check will repeatedly read such locations and check whether the bit value actually changes on repeated reads. When copying such a weak bit to a new disk with a standard FDC controller, it will end up as a distinct 0 or 1 depending on the random state that it was read in and never change as long as the disk remains intact. "Weak bits" are a means of copy protection that generates areas on a disk that read back as random values, without the floppy disk controller actually detecting an error.
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