Well, I had the same problem (see below). For the moment, you can use an older version of mameCE3, or use mameboy instead (which seems to work quicker, but with fewer games supported).

rgds.

> Hi, I just installed the latest version of MAMECE. It starts perfectly with
> roaded game ROMS but I CANNOT ADD coins nor find right buttons on my Cassiopeia
> EM500 (english version). I read all the documents included in the file. It only
> explains KEY MAP for E115 but not EM500. Could anyone explaine to me how keys
> are mapped in EM500? Many Thanks
>