The YM2413 chip contains internal ROM (Read-Only Memory) that holds Yamaha’s proprietary instrument data. Even though the chip is obsolete, Yamaha (or the current rights holders) still hold the copyright to that binary data. The MAME development team has a strict policy:
Therefore, you must download ym2413.zip separately from the MAME application. This keeps MAME legal and forces users to either dump their own hardware (the morally pure route) or find the file from a "non-official" source. ym2413.zip mame
The YM2413's impressive feature set and sound quality made it a popular choice among game developers, and it went on to be used in numerous classic arcade games, including "Donkey Kong," "Dragon's Lair," and "OutRun." The YM2413 chip contains internal ROM (Read-Only Memory)
Many shady ROM sites offer a 0KB file or a renamed version of ym2612.zip (a different chip). Check your file size. If it isn't exactly 2,048 bytes, delete it and find another source. This keeps MAME legal and forces users to
The story of ym2413.zip is a legend in emulation folklore. For years, the YM2413 internal ROM was considered "un-dumpable" because it was a factory-masked ROM inside a resin blob or ceramic package.