> I have come across one floppy (5¼″ low density, mass duplicated, circa 1990) where DTC reported a single track as unformatted and couldn’t read any data (ther

> I have come across one floppy (5¼″ low density, mass duplicated, circa 1990) where DTC reported a single track as unformatted and couldn’t read any data (there was just a bunch of zeros in the resulting image). That is, there were no errors reported at all, DTC simply decided the track wasn’t formatted. There certainly was supposed to be data on that track. > Reducing the default RPM for decoding from 300 to 295 allowed DTC to decode all tracks of the floppy without errors, including the one previously seen as unformatted. I don’t know what that’s about. That sounds like some kind of copy protection scheme.