pause

[danfman]

Is there a way to pause the game?

[gonzo90017]

Hit "P" on your keyboard.

[daywane]

I like to change it to "space bar"
for games not in a cab

[Ginsu Victim]

I like to change it to "space bar"
for games not in a cab

Same here, though I don't play MAME at my desktop much these days.

[u_rebelscum]

To remap the pause key, press tab, select "Input (general)", select "UI Controls", find Pause on the left side, press enter, press the new key.  (mame FAQ)

This will effect all games.