This brings back memories... I worked at a company that used special duplication devices. We assisted with duplication of the game Rogue, and secured it with the main trick of making one of the sectors on the 5 1/4 floppy (might have been sector 8 or maybe 2, I don't remember which track) only half sized, while keeping the sector's recorded stats set to normal sizing (in the FAT? Not sure).
During game load, the executable would get the PC drive to do some kind of absolute positioning to read the "hidden" half sector, which would exist on these specially created discs.
Any subsequent copies made on normal PCs and copying equipment would copy the half sector as a normal full sector, missing the hidden part.
I remember talk about "fuzzy bits" at the time, but I cannot recall if we used them, and whom for...
During game load, the executable would get the PC drive to do some kind of absolute positioning to read the "hidden" half sector, which would exist on these specially created discs.
Any subsequent copies made on normal PCs and copying equipment would copy the half sector as a normal full sector, missing the hidden part.
I remember talk about "fuzzy bits" at the time, but I cannot recall if we used them, and whom for...