@dudleydes "Select" eventually inserts a coin for all roms. However, I have to push a bunch of buttons first before "Select" inserts a coin. I've experimented to see if I need only to wait a certain amount of time, or hit a certain button before Select, however I haven't found any specific requirement other than hitting a bunch of buttons. And this happens for all roms, mspacman.zip, frogger.zip, mappy.zip, dkong.zip, and so on.
It's off topic but fun to mention-- I modified the dkong.zip ROM so that Pauline is the one climbing the ladders to save Mario rather than the other way around. It's pretty cool that it actually worked (i.e., I didn't figure out how to do it, but found a process for doing it on the web).