Because MAME uses CRC32 and SHA1 checksums, a bad ROM (one missing a single byte) simply will not run. The community relies on torrent-based "databases" (dat files) rather than direct downloads.
Once your ROMs are verified, focus on the frontend and controller. Mame 0.250 Roms
Having the ROMs is half the battle. To actually play them with the correct version: Because MAME uses CRC32 and SHA1 checksums, a