klangfeld-labs / doom-os

# DOOM OS: a custom OS for the Roland SP-404MK2
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: 0.6.2-alpha, build 3824 (2026-10-06)
**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** |