The 0.240 CHD set is well-curated – no corrupted dumps of Area 51 or Maximum Force , which were problems in 0.230.
A full 0.240 set includes:
Without these, many games will fail to boot with a "missing ROM or CHD" error. mame roms set 0240
: Rare versions of Helmet , Judge , and Mario’s Cement Factory . and Mario’s Cement Factory .