Maybe my reading comprehension can't grok it, but it appears defeat-able by MFM reading and recreation like almost every other form of "special disk" modification. Kyroflux, greaseweazle, Copy II PC Option Board, etc.
My understanding is that it worked by doing read/write on a known bad sector to verify that the physical defect is there. Replicating that on normal discs sounds hard.
My understanding is that it worked by doing read/write on a known bad sector to verify that the physical defect is there. Replicating that on normal discs sounds hard.