Thanks, Keltron3030 for your quick answer.
Unfortunately, I cannot find a key to show the keypad overlay on screen either. I watched a video on YouTube explaining how to do it with an Xbox1 controller (holding left shoulder button), but I can’t activate it from my 2 joysticks, their buttons, or pc keyboard.
(I’m running retroarch core FreeIntv on Windows 10).
Example of problem game PINBALL:
Key ‘1’ : ask for players (but I can’t ENTER)
Keys ‘2’ or ‘5’ : pause game
Key ‘Alt’ : shows Help screen
This Help screen points out that L/R shows Keypad, but ¿what’s that key in my pc keyboard? ¿Is there a way to remap it?
Example of working game Dig Dug:
Controls work perfectly (player-2 joystick responds for all directions, and any of the keys ‘a’ ‘s’ ‘q’’ ‘Ctrl’ or ‘Alt’ acts as FIRE. No problem at all with this game and many more, but there’re also many, waiting for ENTER to be pressed.
One more (important) thing: I’ve just noticed some games are cropped from both sides. They are playable though, but maybe the keypad remains hidden for that reason, and I’d like to check it out. How could I change the image format to make it fit properly on screen?
Thanks a lot again for your time.