[dirkt]

My favorite one is the spiral tracks on the Apple II, which were possible because all phases of the stepper motor were directly accessible on the controller, so you could move the stepper motor in quarter tracks.

Impossible to copy unless you reproduce the head movements at the right time.

[thewebcount]

Interesting! How did it not also affect reads, though?

[localhost]

The loader would know the needed trajectory of the disk heads. A generic copy program wouldn’t.