people have done floppy<->SD card emulators for over a decade such as here (https://jimatwood.wordpress.com/2011/04/23/sd-card-hxc-floppy-emulator-for-roland-w-

people have done floppy<->SD card emulators for over a decade such as here (https://jimatwood.wordpress.com/2011/04/23/sd-card-hxc-floppy-emulator-for-roland-w-30-s-330-samplers/ https://jimatwood.wordpress.com/2011/04/23/sd-card-hxc-flopp...) It'd take a bit of work but you could probably just go straight to USB and maybe even have some file system trickery where you misreport the amount of "free space" as the host os copies to the "1.44MB" floppy basically by opportunistically "removing and freeing" sectors from the virtual disk transparently, essentially always reporting 1.44MB. It's such a dirty and beautiful hack if it would work. If I were doing this, this is essentially the only approach I'd actually be interested in.