Master System:FM Audio Information

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The Sega Mark III FM Sound Unit; not pictured is the attached 5-pin DIN pigtail cable which connects to the Mark III's AV out

The Sega Mark III was a console launched in Japan in 1985 that was the initial version of the Sega Master System hardware. It was essentially a heavily upgraded SG-1000, featuring a new graphics chip and increased RAM. However, the Mark III still used a derivative of the Texas Instruments SN76489 PSG chip used in that earlier console, which was beginning to show its age by 1985. To rectify this, Sega released an audio expansion in 1987 known as the FM Sound Unit, which connected to the Mark III's expansion port and mixed the console's audio signal via a 5-pin DIN cable. This expansion was based around a Yamaha YM2413 FM synthesizer chip, which was also utilized in several arcade games, consumer-level music keyboards and an MSX audio expansion. Though this chip massively expanded the Mark III's audio capabilities, it was not as sophisticated as the YM2612 later used in the Sega Genesis/Mega Drive and was not fully programmable in terms of instrument patches. Sega would incorporate the FM Sound Unit into the Japanese release of the Sega Master System later in 1987, but did not release it outside of Japan nor did they incorporate the YM2413 into the Genesis/Mega Drive hardware.

Supported Games

A large number of games released from 1987 to 1989 feature FM audio capability, even on Western releases despite the FM Sound Unit never being released or featured in any hardware outside of Japan. This is because Sega used the same ROM file for these games across regions, so the FM audio code remained intact.

Officially Supported

In Japan, Sega used this logo on game boxes to show that the game supported the FM Sound Unit.

These are games which were released in Japan and explicitly advertised support for the FM Sound Unit. The international versions of these games also still retain FM support with a couple of exceptions.

After Burner Megumi Rescue
Alex Kidd BMX Trial Miracle Warriors/Haja no Fuuin
Alex Kidd: The Lost Stars Nekkyuu Koushien
Alien Syndrome Out Run
Aztec Adventure/Nazca '88 Parlour Games/Family Games
Blade Eagle 3-D Penguin Land
Bomber Raid Phantasy Star*
Captain Silver Power Strike/Aleste
Cyborg Hunter/Chouon Senshi Borgman R-Type
Double Dragon Shinobi
Fantasy Zone II Solomon no Kagi
Fantasy Zone: The Maze/Opa Opa Space Harrier 3-D
Galactic Protector SpellCaster/Kujaku Ou
Global Defense/SDI Super Racing
Golvellius: Valley of Doom Tensai Bakabon
Great Golf/Masters Golf Thunder Blade
Hoshi wo Sagashite... Wonder Boy in Monster Land/Super Wonder Boy Monster World
Kenseiden Ys*
Lord of the Sword Zaxxon 3-D
Maze Hunter 3-D/Maze Walker Zillion II: The Tri Formation

*: Only the Japanese versions of these games featured FM audio; the international versions stripped out the FM audio code in order to make room for translated text during the localization process.

Unofficial Support

These are games which will support a detected FM Sound Unit, but this was not explicitly advertised as these games were released outside Japan where the FM audio hardware was unreleased. This is likely because these games used a common sound driver which supported both FM and PSG audio. A few of these games had Japanese releases planned, but these never went through due to Sega discontinuing the Mark III/Master System there early in 1989.

Altered Beast
California Games
Casino Games
Galaxy Force
Game Box Série Esportes Radicais
Mônica no Castelo do Dragão
Out Run 3-D
Poseidon Wars 3-D
Rescue Mission
Scramble Spirits
Summer Games
Tennis Ace
Time Soldiers
Turma da Mônica em: O Resgate (console must be Japanese)
Ultima IV
Wonder Boy III: The Dragon's Trap (console must be Japanese)

FM Audio on Real Hardware

There are several methods that allow you to play your SMS games on original hardware with FM sound.  Some require console modifications and others do not:

Mark III with FM Sound Unit

One of the easier (albeit one of the most costly) options is to simply use an original Sega Mark III with the FM Sound Unit. However, this setup has a number of caveats, the chief of which is that the Mark III is incompatible with Western SMS cartridges due to their different shape and pinout. This can be remedied by acquiring a suitable cartridge adapter. These cartridge adapters are readily available from Aliexpress or eBay, but these leave the cartridge sticking up high from the console and can cause a faulty connection if accidentally bumped or touched. Another issue is that the FM Sound Unit does not pass through RGB so composite video is the only video output option for a stock setup. It is possible to modify the FM Sound Unit with an 8-pin DIN pigtail cable and swap the original 5-pin DIN jack with an 8-pin jack. But as with any physical modification, there is always the slight risk of accidental damage and considering the rarity of the FM unit, this is a modification best left to someone with experience.

Another issue is that the Mark III/FM Sound Unit combination does not mix together both FM and PSG audio. This is especially apparent with the FM audio hack of Sonic the Hedgehog which uses the YM2413 for music and PSG for sound effects.


Tim Worthington sells an FM kit that can be installed in an SMS console.  Installation in an original SMS is fairly simple, as it plugs directly into the rear expansion port, requiring only three wires to be soldered for the FM audio to be mixed with the internal PSG audio.  The kit can also be installed into a Master System II, either via wiring the kit directly into the motherboard or by using a special adapter from Consoles Unleashed. There have also been reports of people installing this kit into a Power Base Converter, or even a Genesis/Mega Drive itself, but no instructions for that are available. These methods also involve wiring the kit directly into the host console's motherboard.

Power Base Mini FM

The Power Base Mini FM is a cartridge converter designed by dB-Electronics for the Genesis/Mega Drive which provides backwards compatibility with SMS cartridges, complete with additional FM audio through an onboard YM2413. This will also work with SMS flash carts such as the Master Everdrive. Card games and the 3-D glasses adapter are not compatible due to the lack of a card slot.

Japanese SMS/MK-2000

Another option is the Japanese Sega Master System console (model number MK-2000), which has a YM2413, 3D glasses adapter and rapid fire module all built into the console itself. These were all separate add-ons for the Mark III.  However, like the Mark III, the Japanese SMS is not compatible with non-Japanese cartridges and will require a cartridge adapter for these games. These cartridge adapters are readily available from Aliexpress or eBay, but these leave the cartridge sticking up high from the console and can cause a faulty connection if accidentally bumped or touched.

Another solution for the JP SMS is the SMS Gender Adapter, which connects to the expansion port at the rear of the console. Though this provides a cleaner solution for playing Western cartridges, it does have some compatibility issues with certain games and flash carts.

Genesis/Mega Drive Flash Carts with FM Support

Several Genesis/Mega Drive flash carts such as the Mega Everdrive Pro, Mega Everdrive x7 and Mega SD can provide FM audio through FPGA emulation of the YM2413, the output of which is then routed into the Genesis/Mega Drive. This is probably the most feasible solution for those who play Master System games via a Genesis/Mega Drive and want to experience FM audio on compatible games.

NEO Myth Cartridges

In addition, there is another, much older flash cart known as the NEO Myth MD 3in1 which, like the Power Base Mini FM, has an actual YM2413. The same company also produced a Master System variant that also features a real YM2413. Unlike the Genesis/Mega Drive cartridge, this requires the SMS's audio output to be mixed into the cartridge since the SMS does not have an audio input on its cartridge port. This is not unlike the original FM Sound Unit, which had a hardwired cable to mix in audio and pass through video from the attached console.

Unlike the Everdrive series and Mega SD, the NEO Myth carts are not "plug and play" and require additional software to read and write ROMs. A microSD card adapter is available, but is considerably expensive and still requires the software for initial setup (although after setup is complete, ROMs can be read and written to the SD card like a modern flash cart).

Due to their antiquated UI, need for additional software, limited capabilities compared to modern flash carts, and use of expensive flash modules, the NEO Myth cartridges are not recommended.

Comparison of the above methods: