Just wanted to say thanks to Lawrence and Gamesx.com! Thanks to the awesome information here I was able to build this new adapter that lets Genesis controllers work on PC Engine :)
https://segasonicfan.wixsite.com/retro/uni-gen
It's cool that I'm still learning things here after so many years 8)
-Segasonicfan
That looks awesome, man. Glad this site could be helpful. ^_^