ROMdb β Playing is overrated

As you may know, each version in ROMdb is identified by its CRC32. To be more specific, by its "clean compound" CRC32: a) some files are not included (e.g. .cue files in optical disc dumps), and b) when versions are composed of multiple files, the sum of all relevant files' CRC32 is computed.

That approach wasn't good enough for MAME because BIOS ROM files are included in each game. Any new BIOS file in a new version of MAME would change the compound CRC32 of all the games including it. That situation would inevitably render all affected game entries in ROMdb obsolete and create new ones completely empty of metadata (parent game, release year, screen title, screenshots...). A good example of this issue were the dozens of Neo-Geo games.

The problem has been solved now by ignoring BIOs files. Unfortunately and inevitably, in the process all versions with BIOS files have changed (for the last time) their CRC32 with the last .dat update of MAME to version 0.238. You will see many obsolete ROMs in arcade versions index that eventually have to be manually deleted. The process will be slow and tedious but it'll pay off in the mid-long term.