Master System:SMSFM

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The Sega Master System FM Expansion Board, or SMSFM for short, is a modification board designed by Tim Worthington which adds FM audio capability to a western Master System console.


In Japan, the Sega Mark III (the original guise of the Master System) received an FM Sound Unit accessory, which contained a Yamaha YM2413 FM synthesizer chip that added enhanced audio to games which were compatible with it. The FM Sound Unit was also built into the Japanese version of the international Master System. However, Sega never added the YM2413 to any SMS hardware outside of Japan or even to the later Genesis/Mega Drive, meaning that these games would be stuck with PSG audio on non-Japanese hardware.

The SMSFM board changes that and allows for FM sound to be heard on non-Japanese hardware for the first time. It is largely based on the FM Sound Unit, but has some additional features. Beginning with the 2.0 revision introduced in 2013, the SMSFM board also has the ability to change the host console's region between English and Japanese, necessary for FM sound on Wonder Boy III: The Dragon's Trap to function. The SMSFM board can also be turned off if one prefers PSG audio for certain games, and for games which do not function if they detect an FM unit (i.e. Wanted, Walter Payton Football)

Materials and Tools Required

  • JIS/Phillips head screwdriver
  • Soldering iron
  • Desoldering braid or desoldering gun
  • Leaded solder
  • Flux (not required but recommended)
  • Wire
  • Wire cutters and stripper
  • Flush cutters
  • Drill with step bits


Model 1

See this guide or the official written documentation.

Sega Master System II

See the official written documentation.

TecToy Master System/Master System II

See the official written documentation.

TecToy Master System III Compact

*To be written*

Sega Mark III

See this guide for further information.

Genesis/Mega Drive

*To be written*