Here’s a howto for making a Mitsumi D359M3D compatible with the MSX.
Setting the drive to DS0:
Cut the trace from the IC to pin 12
Solder a wire from the cutted trace (on the IC side) to pin 12 (brown wire)
On my drive I used a quick & dirty fix, to put a solderjumper on pin 10-12
This way the drive is reconized as Drive A, but can’t be used in machines with 2 drives.
Put Disk Change on pin 2:
Make a solderjumper on DEN2
Put READY on pin 34:
Cut the trace from pin 34
Solder a wire from pin 34 to the 2nd solderpad from the left of the 6 pads on a row (white wire)
Seeing multiple Mitsumi Drives having the NCL039 controller, it is almost save to assume that the RDY signal can be found on pin 35 of th NCL039. This makes it possible to make all drives using this IC MSX Compatible.
Now the drive can be used in your MSX (or in your Amiga or Korg or Yamaha)