Note: This feature is experimental - it's quite different to the other features in the firmware, all of which generally involve simulating read-only media.

Support for the Roland SP808/EX is provided by implementing the SCSI “Ultra-High Density Floppy” specification. This basically implements a normal read/write device but with a few extra commands dealing with formatting. There's also a few vendor-specific commands that the Roland expects.

The firmware currently requires a UHD floppy image to be selected to simulate the writable disk. Otherwise, it will default to a CD/DVD-ROM drive, and the SP808 will run slowly (as it continually attempts to figure out why the drive isn't a UHD floppy drive).

The SP808 appears to be sensitive to image sizes. They can vary, but if they're not something like what it expects, it will be unable to use the image and continually ask to format it.

Images used by the firmware have the 'mdi' extension, for “Magnetic Disk Image”.

To create a disk, you can use the Unix/Linux command 'dd' as such:

dd if=/dev/zero of=blankimage.mdi bs=512 count=489532

489532 sectors at the standard sector size of 512 bytes will create an image the same size as a real 250Mb ZIP disk, which seems to make the Roland happy.

Once the image is created, installed on an SD card or USB drive, and plugged into the Roland, it will ask to format it. Do a “full” format and everything should function as expected. Remember to save your songs after editing or the Roland won't know to do so, as there's no eject button anymore!