Making an MFM encoded floppy reader with a microcontroller

Reading and writing the data on a floppy disk is one task. Another is translation to/from the modified frequency modulation (MFM) data that the floppy stores. Peter Schranz looks to tackle this:

Floppy Disk Controller chips (FDC) are now obsolete and so I thought about emulating a FDC using a microcontroller. I also could have used new old stock controllers but that was not my intention.

In the internet you find several discussions about this topic and in many cases the conclusion was that it is not possible to read floppies without a controller. However, there are also some projects describing a floppy disk emulator using a microcontroller with no or only little hardware support. Also there are several projects that read the raw MFM data and send it to a PC to decode the data. I was really tempted to give it a try.

My goal was to read and write HD floppies without any additional hardware and be able to read and write the content of individual sectors.

See the code Peter uses to do MFM encoding for his project in the blog post here.


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