[jedberg]

My favorite copy protection was on some games I had (I want to say they were Microprose games? But I could be wrong) where they would cut the hole in the disk just slightly bigger, and then take advantage of the fact that in DOS you could talk directly to the hardware to convince the read head to go just a little too far. Then it could read the magic 41st track to load the game, but no disk copy program could copy it.

[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.

[userbinator]

Some of the "floppy extender" programs used more than the usual number of tracks, so unless the 41st was hidden somehow so that its existence was a secret, it would be no harder to copy than all the others.

Of course, that may well be why it was so successful --- the extra track wasn't well known, and information travelled much slower back then.

[FpUser]

Nah. I remember those days. Programs that could read/write/discover more tracks than the standard amount were widely available.

[jedberg]

Well, it was 30 plus years ago, but what I remember is that at first it was just the games that were doing it, and then people figured it out and made those other programs, making the copy protection useless.

[marzell]

There was a similar situation with CDs where you could overprovision data that existed past the technical limit of useable range. I think that's was utilized in NINs Year Zero ARG experiment.

[peteretep]

There were also hidden tracks before track 1 iirc. The X Files soundtrack had one