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klangfeld-labs/doom-os

The Offical DOOM OS repository

View on GitHub ↗https://klangfeldlabs.com/doom-os ↗
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Created Sep 28, 2026Updated Sep 30, 2026

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README

DOOM OS: a custom OS for the Roland SP-404MK2

DOOM OS

DOOM OS is a heavily modified version of the original 5.52 firmware. It adds a graphical pattern sequencer, a mixer, effect automation, custom shortcuts and more, and improves parts of the original firmware. You patch it yourself, in your browser, using the official firmware file from Roland.

Current version: 0.6-alpha.

Quick installation: Use the web patcher to install DOOM OS

Features

  • Pattern sequencer with a graphical interface: see and edit your pattern as a grid while it plays
  • Piano roll: play melodies in on the pads
  • Live recording with a rehearse mode, quantise, swing, fixed velocity and note length
  • Eight pattern tools: quantise, swing, shift, double, halve, reverse, humanise, transpose
  • Track and pattern settings: mute, solo, volume, swap pad, paste, clear, tempo, pattern length
  • Mixer with a live level meter for every track
  • Effect automation: record your effect knob moves and edit them step by step
  • Zoomed view of four tracks
  • Undo and redo, 12 steps
  • Help mode: press any control to see what it does
  • Custom shortcuts (key combos)
  • A DOOM OS tab in the system settings
  • Six boot animations

Improvements

  • Safer saving: a pattern is written to a new file first, and the old file is only removed once the new one is complete
  • Slightly faster boot time
  • Everything from the original firmware still works: DOOM OS doesn't remove or replace anything

How to install

The easiest way to install DOOM OS is by using the web patcher:

https://klangfeldlabs.com/doom-os/patcher

You can also download this repository as a ZIP file (under the Code button), unzip it and open index.html in your browser. Just follow the instructions on the page.

Manual installation

  1. Download the 5.52 system update from Roland's support page and unzip it.
  2. Open the patcher and load SP404MKII_APP1.bin. Everything happens in your browser, nothing is uploaded. The patcher only accepts the official 5.52 file and checks the result against checksums.txt.
  3. Download the patched SP404MKII_APP1.bin and copy it to the root of your SD card.
  4. Insert the card, hold SHIFT while you turn the SP on, and press the VALUE knob when the update menu appears.
  5. When the update is done, turn the SP off and on again.

To go back to the original firmware, just run the updater with the original Roland firmware.

Main controls

Control What it does
REMAIN + SUB PAD Open DOOM OS (works from any screen)
EXIT Close DOOM OS and save your changes
Hold SHIFT for 3 seconds Help mode: press any control to see what it does
PATTERN SELECT Start / stop
Pads 1-16 Turn steps on or off in the selected row
Turn VALUE Select a row
Hold SUB PAD + tap pads Choose the sample for a new row
Hold a step + CTRL 1 / 2 / 3 Velocity / length / timing of that step
Hold a step + SHIFT + CTRL 1 Pitch of that step
Hold a step + press VALUE Open the piano roll
HOLD Play the pads instead of editing steps
REC Press once to rehearse, again to record
PATTERN EDIT Pattern tools
RECORD SETTING Track panel, pattern panel and mixer
SHIFT + PATTERN SELECT Undo
REMAIN + PATTERN SELECT Redo

The full guide and every control are in the manual.

Coming next

Song mode, a sample editor, an effects editor, a guided tutorial, and an SDK so you can build your own screens.

Status

This is an alpha. It has been tested on my own SP-404MK2, but expect some rough edges. Found a bug? Open an issue and include the version shown on the VERSION tab in Utility → System. Changes are listed in CHANGELOG.md.

Disclaimer

This is an unofficial project, not affiliated with or endorsed by Roland. Modifying your firmware is at your own risk and may void your warranty. DOOM OS is named in tribute to MF DOOM. Made by Klangfeld Labs, MIT licensed (LICENSE).