Magical FDS Plug (English)
Magical FDS Plug is a software synthesizer plug-in that reproduces the sound of the The Disk System (FDS) sound chip. It can be used within Mac / Windows host applications that support Audio Units and VST3.
The FDS sound chip features a unique architecture in which a 64-sample waveform memory (carrier) is modulated by a separate 32-step instruction sequence (modulator). Despite its steep learning curve, Magical FDS Plug preserves the full flexibility of the original hardware while providing a logical interface for building waveforms — through additive synthesis, presets, and more.
Features
- Carrier + Modulator — two independent signal paths. Design the audible waveform (carrier) and its modulation sequence (modulator) separately.
- Logical waveform editing to take the guesswork out of FDS sound design:
- Additive Synthesis — Drawbar-style, like a tonewheel organ. Mix harmonics with 8 sliders.
- Preset Waveforms — Start from triangle, sawtooth, or sine wave, then reshape the tone via compression and expansion.
- Pulse Waveform — Shape the waveform by adjusting the pulse width (1–63) of a square wave.
- Freehand Drawing — Draw a 64-point waveform directly using sliders.
- Modulator: 6 presets + Custom — Triangle, sawtooth, sine, square, ramp up, ramp down. In Custom mode, enter a 32-step opcode sequence (32 digits, 0–7) as text.
- Modulation rate modes — Three modes: LFO (slow, cyclic modulation), FM (timbral modulation), and OFF.
- ADSR envelopes for both carrier and modulator — Shape the volume and modulation over time, with the same workflow as Magical 8bit Plug 2.
- Hardware-accurate output filter — A ~2 kHz low-pass filter modeled on the original hardware, switchable on/off (default: on).
- Preset save / load — Save and load all parameters as an XML file.
Demo
Carrier and Modulator
| Part | Role | Details |
|---|---|---|
| Carrier | The audible base waveform | A 64-sample, 64-level (6-bit) wavetable. Can be built in four ways: additive synthesis, preset waveforms, pulse waveform, or freehand drawing. |
| Modulator | An instruction sequence that alters the carrier’s readout speed (and thus its timbre) | Operates as a 32-step, 3-bit opcode sequence. Choose from 6 presets including triangle wave, or specify opcodes directly in Custom mode. Rate and depth controls allow LFO-style or FM-style effects. |
Specifications
| Parameter | Details |
|---|---|
| Polyphony | 1–32 (default: 1) |
| Carrier waveform modes | Additive Synthesis / Preset Waveforms / Pulse Waveform / Freehand Drawing |
| Carrier waveform | 64 samples, 64 levels each (6-bit) |
| Modulator | Triangle / Sawtooth / Sine / Square / Ramp Up / Ramp Down / Custom (32×3-bit opcode text) |
| Modulation rate | 1–4095 (LFO: 1–30 / FM: 30–4095) |
| Modulation depth | 0–63 (LFO: 1–5 / FM: 0–63) |
| Modulation mode | LFO / FM / OFF |
| Envelope | ADSR (Attack / Decay / Sustain / Release) for both carrier and modulator |
| Controller support | Velocity (0–127) / Pitch bend (±0–±24 semitones) |
| Output filter | Hardware-approximate low-pass (~2 kHz), switchable on/off |
| Color themes | 7 themes (FDS / YMCK / YMCK Dark / Japan / Worldwide / Monotone / Mono Dark) |
| Presets | Save / load as XML file |
Operation environment
 | macOS applications that support Audio Units and VST3 (macOS 10.13 or later) |
 | Windows applications that support VST3 |
Download
- This software is distributed under the GPLv3license.
- Copyright is held by Yokemura (Takeshi Yokemura of YMCK).
- Music and tracks created using this plugin may be used freely, whether for commercial or non-commercial purposes. Credit is appreciated but not required.
- Redistribution, resale, or paid distribution of the plugin itself is prohibited. This includes distributing modified or repackaged versions, as well as the plugin file on its own.
2026.06.25 Release
- Comments from Yokemura, Developer at YMCK On the Release of the Magical FDS Plug
YMCK's music has featured FDS-style sounds quite a few times over the years — but honestly, they were always just approximations, patched together with regular synths. The rest of our tracks use Magical 8bit Plug to get close to real hardware, so having that one part stubbornly refuse to match had been bugging me for a long time.
The thing that kept stopping me was how complicated the FDS spec actually is. Reading through it and turning it into working code takes a serious amount of patience, so I kept kicking the can down the road. But with AI tools getting genuinely useful lately, I finally had enough help to just go for it.
The trickiest part was figuring out where to stick with the original spec and where to do my own thing. I went back and forth on it a lot, but in the end the main changes were swapping the original linear-only envelope for an ADSR, and adding polyphonic support. Pretty much everything else is spec-faithful.
Now we can actually get a real FDS sound out of this thing — and I can finally use it in our music without second-guessing myself. It's a genuinely fun and quirky sound source, so whether you make chiptune or something else entirely, I hope you'll mess around with it.