Just thought I’d share something I found while searching for keymap information on Mednafen.
I did my initial setup using this tutorial: Mednafen Setup Tutorial
Unfortunately every time I started Mednafen it would override the keymaps I carefully setup with the default configuration file.
After doing some searching on the issue, I found that Mednafen comes with a simple control binding setup in-game, meaning I don’t have to look up keyboard codes.
After loading a ROM, press ALT+SHIFT+1 to bring up the keyboard input setup.