The vfloppy disk simulator is software that acts like a disk drive for the Epson HX-20 and PX-8 systems. It is written in C, for Linux. It's regularly updated, and now supports the D88 virtual disk file format used by the PX-4/PX-8 emulators produced by Toshiya Takeda.
All the software in play here is GPL/open-source, which is awesome. Having an open, working, updated implementation of the disk drive simulation will be very helpful in my efforts to produce a Propeller-based virtual drive.
This is the most current and best solution I'm aware of for emulating the Epson PF-10 floppy drive on a modern system, so I'm off to install Linux on a spare machine. Rather than use a virtual machine and have the potential hazards of uneven serial port support, I'm putting this on real hardware. I'm going with Ubuntu 10.04 on a Dell Inspiron laptop. Will be nice to take the new Ubuntu for a test drive anyhow!