6.6.5 Mitsumi D359T6 Floppy

Mitsumi D359T6 Floppy

I just had a look during the weekend, so for all interested, here are the changes you need to perform to a Mitsumi D359T6 floppy drive to use it on an Atari (ST/TT/Falcon). The Mitsumi drive was the only one I could find nowadays. It seems to be the cheapest and most widespread floppy drive used nowadays in most OEM, brandless and homebuilt PCs.

To change the drive ID, this unit has no jumpers, however, on the connector PCB you'll find a small area with 3 rows of 4 tiny solderpads. You have to make 2 solder bridges, like this (viewed with the connector to the bottom and the front of the drive facing up)

o o o o
o o=o o
o o o=o

With this, the drive will be detected by the Atari, but you may experience problems with the Media change: when you swap disks, the Atari can ignore the swap, and writes to the new disk using FAT information of the old disk. This usually corrupts all the data on the disk, and makes it unrecoverable.

The enable the media change detect, you can solder together 2 pins of the write protect/media change switch (top left of the drive, marked WP and MC). Bridge the MC and middle pins like this:

 |_____|
W | | | M
P | |=| C

I haven't tested that part yet, but read a post from somebody claiming that this corrects the media change bug. I still use the fmc.prg in the AUTO folder as a precaution.

If you want to do the HD mod, then you'll find that pin 2 of the mitsumi connector does not output +5V when a HD disk is inserted, as it should. A way around this, is to run a wire directly from the HD detect switch to pin 2 of the connector. The HD switch is the one opposite to the WP/MC switch, and has a pin marked HD. You should solder one end of the wire to this pin, and the other to the connector PCB, where the pin 2 is soldered to the board.

I suspect that the HD detect and Media Change settings can probably be changed from the "4x3 solderpads" area, but I was unable to find a way to do so. Maybe someone else has some better information.

technical information: Nicholas Bales, Toulouse, France