Super Mario Bros 1 Menu not working

[MottZilla]

I seem to recall SMB's menu wouldn't respond in some emulator I was using because the second controller's input was doing something because I had two controllers on my PC but when the second one is disconnected (its a PS1 adapter with 2 ports) it has some garbage input instead. I never investigated it but I do know that plugging in a second controller allowed the game to work. So perhaps player 2's input values were causing the game not to respond to player 1's input. I forget but there may have been other games I had issues with like that too. And it wasn't my own emulator, it was Nestopia, and it worked just fine if a valid 2nd controller was hooked up.