Rollback Set

A Rollback Set is used to create older ROM sets for previous versions of MAME.

That's needed to run on old hardware, or to play a game that does not run in the latest version of MAME.

To create a Rollback Set you need to get the latest MAME set, the latest Rollback torrent, and rebuild it yourself using clrmamepro or RomVault.

And of course you need the DAT File of the set you are planning to make.