A complete, non-merged MAME 0.250 ROM set (excluding CHDs) is approximately 68 to 72 GB. If you include the CHDs (hard drive images for games like Killer Instinct or Dance Dance Revolution), the total can exceed 500 GB. Most users opt for a "split" or "non-merged" set depending on their storage needs.
If you go looking for "Mame 0.250 Roms," you will immediately encounter two terms: Split and Merged. Mame 0.250 Roms
To understand this, you must understand Parent/Child ROMs. A complete, non-merged MAME 0
Recommendation for 0.250: Most advanced users prefer Split sets for arcade games because they allow you to cherry-pick which clones you keep. Recommendation for 0
Warning: ROM files are copyrighted. Only use ROMs you legally own or that are public-domain/abandonware in your jurisdiction.
(For an exact changelog, consult the MAME 0.250 release notes and driver changelog.)