[londons_explore]

I'd be interested to see the results of mounting a much smaller head (eg. a hard drive head) to the floppy drive, and then creating a full 2D image of the disk surface magnetics.

That should be able to read disks where the disk surface has stretched or warped, and the tracks are no longer perfectly circular.

I think there's also a reasonable chance such a method could also be used to recover data on a disc that has been overwritten.

[NegativeLatency]

Related to that there are many different copy protection schemes and other formats for writing the data that don't result in circular tracks. Lots of old computers addressed the drive at such a low level that it was possible to directly control the head between tracks, and control the rotational speed of the disk.

For example there's this project that reads stranger formats http://cowlark.com/fluxengine/

[dirkt]

You mean something like this?

https://en.wikipedia.org/wiki/Floppy_disk#/media/File:Visual...

[PostThisTooFast]

Some drives (like those for Atari 8-bits) were intelligent, so software didn't have direct control over the recording parameters. So publishers would create custom authoring drives that could write bad sectors on command; the program loader would check for a bad sector and refuse to load if it wasn't present.

A more-clever technique would write two sectors in a row with the same sector number but different data in each. The program loader would rapidly demand that sector twice, getting different data as the disk passed under the read head. A copy program, however, would only copy each sector once and be missing the data from the sector with the duplicate number.

[userbinator]

A more-clever technique would write two sectors in a row with the same sector number but different data in each.

This is also done in some optical disc copy protections, although the identically numbered sectors are far apart, causing seeks from the end to return different data than seeks from the beginning of the media.

[seryoiupfurds]

Hey @PostThisTooFast, you seem to be shadowbanned based on two flagged comments when your account was new in 2015.

Hey @dang, this account has made many good comments since then.