This device is intended for Amiga 500/500+/2000/3000 range of retro computers. It makes the external drive (DF1) appear as an internal drive (DF0). This enables you to boot from the external floppy drive, which is super handy if the drive in question happens to be a Gotek / HxC floppy drive emulator.

This mod is nothing new and can be done by swapping a few pins of the Complex Interface Adapter (CIA) chip. However, I didn't like the existing products as they use a DPDT switch and long wires for doing the switching. This is a bad idea as the ICs are rare and very sensitive; also the needed switch is kind of bulky and has complicated wiring. The existing products are also quite expensive when you take shipping into account.

This product uses a multiplexer chip to do the signal switching on the PCB. In other words, the signals of the precious CIA chip are not taken off the board. The switch - which can be of simple on-off type or even a jumper - is used only for controlling the direction bit of the multiplexer.

The kit comes pre-assembled - you just need to connect it to the switch of your choice and install the CIA chip (not included) and you are ready to go!