The Internet Archive hosts many vintage computer ROM sets. You can often find "Roland MT-32 Rev 0, 1, 2, and CM-32L ROMs" listed under "software" or "firmware." Downloading from the Archive is low-risk, but understand that you are relying on "abandonware" gray areas.
: Contains the actual instrument sound samples used for music synthesis. Popular Emulators & Tools mt-32 rom download
: The software that runs the unit's microprocessor. The Internet Archive hosts many vintage computer ROM sets
If you own a physical MT-32, you can dump the ROMs using an Arduino or a EPROM programmer. Tools like mt32romdump are available on GitHub. This yields 100% legal, perfect files. mt-32 rom download