Maybe this is a dumb question, but I'll ask anyway. Why are some MAME roms, even if seemingly unupdated, not backward compatible?
Example: Download the latest crush.zip (Crush Roller) or crush2.zip/crush3.zip. Run it in MAME 0.59. Doesn't work! It says "missing crush.4a". How come it was removed, even if the rom crush.zip has been in mame since 0.1?