I run maniac mansion with the AD flag and it works. But in the welcome screen I can’t move the pointer, so I can’t start the game
You must set the AD flag and the J1, because it only works with joystick in Port 1. Unfortunately, the C64mini defaults with Joystick in port 2.
Yeah, now that you make me think of it, the vast majority of games used port 2. How come? Anyway, good for me. After 3/4 years, the port 1 of my C64 broke.
My best guess is, because the KERNAL of the C64 miss interprets movements in port 1 as character input from the keyboard. Unfortunately, the control ports and the keyboard share the same lines. You need to code additional measures to keep them apart. Not many games use the KERNAL routines anyway, but some do.
I guess, every C64 user thought the keyboard was broken at least once, but it turned out that one of the joysticks were in autofire mode, causing the issue.