Yamaha DX7II/DX7IIFD
Yamaha DX7 Family - Digital FM Synthesizer
DX7II Disc Drive Format
The DX7II FD's Disk Drive and some older Yamaha gear use the old MSX 8bit computer disk format! yes, its the japanese "standard" for 8bit computers that was created quite late (the 8bit-era ended quite soon after and with MSX).. so, if you want to read the Disks (eg for importing into Native Instruments FM7 or fmheaven) you need a tool to read from MSX formated disks.. well.. uuhm.. try www.emulation.net but most progs only emulate the machine but not the physical disk format..
Link
- Info DXII Series http://www.sequencer.de/yamaha/yamaha-fm-synthesizer.html