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I've started work on a project to read floppy disks at the analogue level.

Stuff like Kryoflux uses the digital output of the drive only. I want to capture the analogue waveform, as you would see on an oscilloscope if you probed the output of the amplifiers on the drive.

The advantage of this technique is that even tricky copy protection schemes like Rob Northern CopyLock that use "weak" bits can be accurately imaged and preserved. It should also be useful for recovering data from damaged disks.

Of course the floppy drive will have to be modified so that the analogue signal can be read. Depending on the drive it might be possible to simply attach a probe to a test point or the leg of an op-amp, or otherwise add an attachment point with a bit of soldering.

I'm aiming for at least a 2msps sample rate, ideally 4msps which is the maximum that the XMEGA microcontroller I am using can capture. It has 12 bit ADCs but 8 bits is probably more than adequate for this task. There are faster ADCs available but this should be fast enough and is very cheap and easy to handle the timing.

The MCU has a DAC as well but it's only good for up to 1MHz. That is probably enough to write disks though. My understanding is you only need a 250KHz clock for standard density disks, although maybe some copy protection schemes went beyond that to create deliberately impossible to copy timing errors. In theory though it should be possible to write exact duplicates of copy protected disks.

I'm working on the hardware side now, component shortages mean prototypes can't be built yet. Interested in feedback on this idea. I know some people do analogue data recovery using custom hardware or oscilloscope waveform capture already.