Hi Flavor, how's the project going?
i just thought of something I'd like (and I don't know if it exists); a PC Engine to USB converter. It would involve coding a driver, but if emulators have multitap support, that would be killer - take a laptop out and hand around the joypads!!!
Good timing. I was thinking of posting an update today. Here's some tech mumbo jumbo that may or may not be interesting.
The vid I posted before was my first attempt, and I built it with a microcontroller doing the work. I was very pleased with the layout of the code and how it would be easily extensible (to more controllers or custom button mappings or whatever). However, the microcontroller proved to be too slow for anything but that single 2-button controller shown in the video.
I've been slowly working on setting up a redesigned version using a CPLD as the main "brains". Last night I was able to get that up and running for the first time. Again, this initial test was just a single controller, but the CPLD way of doing it should mean that adding more controllers/buttons shouldn't slow it down at all.
So, the good news is that the project is finally back on track and working great. I don't have a vid of the new version, but really it would look about the same as the previous video. It's just a different mess of wires this time.
I have seen devices like the one you've described. I know they exist for NES, SNES, PlayStation, etc. I don't know if I've seen a PCE version, though. The nice thing is that coding the driver would be pretty easy since it could just build on the other previous designs. I think there was some open-source stuff. I have no idea if these converters would support multitap, though. My guess would be NO. You would probably use 1 converter per controller.