handheld fm groovebox

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FMS is a groovebox for the Nintendo® Game Boy™ Advance handheld video game console. Its focus lies on quick and intuitive programming of sounds and music, for live performance and studio recording - or just having fun.

At its core is four tracks of 2-OP FM synthesis running in realtime - a world first for the GBA. Paired with the Noise channel from the original integrated Game Boy™ hardware, it's a perfect blend of high and low resolution.

egak by nullsleep
rp-fwz by 0f.digital

Made for the Game Boy Advance

The GBA was a portable powerhouse when it first launched in 2001, and 25 years later its charm remains undeniable.

Handheld game consoles has long been a staple in the chiptune community for good reason - the limited control scheme and pocketability makes for an immediate music production platform that you can bring anywhere.

While FMS is built for the GBA hardware, it can be used on all kinds of old and new devices since emulators are both widespread and accurate. Computers, phones, Linux handhelds, FPGA systems, even other game consoles - it runs on almost anything.

snapper by mikeyfm
ratchet by 0f.digital

Advanced sequencing

Every single sequencer step can play a unique sound, with per-track length, rate, shuffle and trigger-every-nth-step logic. Notes can be quantized to a scale, steps can allocate voices as a chord and a powerful note echo effect can be used for everything from simple echoes to arpeggios.

Patterns can be mixed and matched, randomized and queued - you can even take a snapshot, mess up your pattern and instantly cycle between states. Everything is designed with live performance and immediacy in mind. And on top of that, you can make longer progressions or unexpected melodies with the transpose sequencer.

FMS also supports external sync via the Link Port - connect it to another GBA with a link cable, analog clock with a DIY connector or receive MIDI via the Arduinoboy or Analogue Pocket MIDI-in cable.

pienois by keff
loops by nullsleep

FM + noise

FMS has four FM synth tracks and one PSG noise track, each utilizing different aspects of the GBA hardware. The FM tracks implements 2-OP FM synthesis using the Direct Sound registers of the GBA with custom DSP while the Noise track uses the integrated Game Boy™ hardware.

Together they shape a retro-futuristic sound palette where the FM synth can be used for all kinds of sound design, sprinkled with some classic video game noise on top.

coupling by nullsleep
error by sm0hm

To sum it up

4 × 2-OP FM synth

  • a/h/r envelope
  • fractional mod ratio
  • mod feedback
  • mod a/r envelope
  • pitch envelope
  • stereo panning
  • portamento

1 × Game Boy™ noise

  • a/h/r envelope
  • wide to narrow rate
  • stereo panning
  • portamento

16-step sequencer

  • unique sound per step
  • individual track length
  • individual track rate
  • individual track shuffle
  • note echo per track
  • per-step chord allocator
  • transpose sequencer
  • snapshot recall
  • trigless steps
  • randomization
  • 128 patterns per track

Dive into the user guide to learn more

... or check out our video walkthrough

Still got questions? Hit us up via hi@lo-bit.club

© 2026 Lo-bit Club, distributed by Fors FM AB

"Game Boy Advance" and "Game Boy" is a registered trademark of Nintendo.
This software is not affiliated with, licensed or otherwise approved by Nintendo.