ExecFile("c:\mame\mame.exe bublbobl") should work, assuming that the correct path for mame.exe and %1 are provided, and this is the proper way to tell mame to load a file. It's possible that %1 is not using the full path (ie x.y instead of c:\mame\roms\x.y) or that it requires quotation marks to surround it (in that case, it would be ExecFile("c:\mame\mame.exe "+Chr$(34)+"bublbobl"+Chr$(34))).
BTW
%1 = first command line parameter.
BTW
%1 = first command line parameter.