PS1 Controls on Raspberry Pi RetroPie Explained
In this video we walk through the different controller setting for playstation 1 (PS1, PSX) in RetroPie for Raspberry Pi. There were some changes as the system matured from just a d-pad to d-pad plus analog sticks, then they added a multitap for 4 players.
You can hold down your mode key (typically coin) and press X (typically top middle button for player 1) to access Retropie setting.