I know this is an old thread but has anyone of you got any further investigating the microdrive emulation ? On this forum and on the tlienhard.com forum I started threads about my emulation effort with an mbed
http://mbed.org as slave device to the QL emulating a microdrive.
So far I have succeeded in decoding the data coming out of the QL during the format command and am now in the process of emulating the signals back to the QL. Unfortunately although the decoding of the format command signals work, snooping onto the signals during a dir or load command from that working MD tape does not. The timing is somehow different, probably because of motor/tape speed variation. My emulator does not have a PLL function (yet).
For now I am trying to get a directory on screen from an emulated MD tape image file I found with the QLAY emulator (MDV1.MDV).
Maybe I can use the TKII ram disk function to get an image of my only working MD tape I have left (already replaced the pad) and try to get that somehow out of the QL and onto my programming system.