Chris, I, too, tried a similar thing. It mostly worked until there was a need to switch quickly between the two drives (booting the diagnostics, for example).  Then it worked strangely. What I believe may be going on is that the Pro is relying on the fact that, although there appear to be 2 drives attached, they are using the same head positioning -- they seek in parallel. I thought about hacking the Flashfloppy code to pay attention to the drive select and allow a single Gotek to emulate both drives (and take into account the parallel seeking), but I just ended up using a real RX50 to boot diagnostics and that was good enough at the time.  The big problem is that the Flashfloppy would need to have 2 disk images mounted at once.  There's a problem of limited RAM in the Flashfloppy, but there's also a problem of the UI which is really set up for only a single image. --Bjoren On 3/2/2023 3:25 PM, Chris Zach via cctalk wrote: > Seems like it should be simple, but it is not. > > I have a pair of Goteks with the Flaashfloppy code and each one has a > USB with 400k RX50 images on it. Both are set to drive 2, and a > standard 40 pin floppy crossover cable allows me to emulate a pair of > drives. > > Now, I want to replace the RX50 drive on my Pro/380 with this setup to > allow it to install POS. However it does not work, the Pro fails > startup with an error on the floppy controller board, and so far it > looks like POS can't see the disks. > > So what is the difference between an RX50 and a pair of 5.25 drives, > and is it possible for Flashfloppy to emulate whatever oddness is in a > true rx50? > > CZ