DOOM-OS Etc.
firmwaregithub.com
DOOM OS fork with a four-voice Sound Generator and an arpeggiator. The patcher builds Sound Generator + Kits on DOOM OS 0.6.1, so your firmware includes DOOM OS as well.
Mudb0y2026.10.064 on GitHub
Tallfree is a screen reader for the Roland SP-404MKII. It's modified firmware that reads the screen aloud, so a blind musician can get at the menus, settings and sample names that are otherwise locked behind the display. The voice is OpenEVV, a reimplementation of IBM's Embedded ViaVoice, running on the SP itself. If you've used Eloquence, it will sound familiar. Tallfree isn't made or supported by Roland. You install it at your own risk, but you can always go back to Roland's firmware; see below.
Compatible with
firmwaregithub.com
DOOM OS fork with a four-voice Sound Generator and an arpeggiator. The patcher builds Sound Generator + Kits on DOOM OS 0.6.1, so your firmware includes DOOM OS as well.
firmwareopensp.fyi
An open set of firmware, tools, and guides for the Sp-404MKII. The project is focused on providing an open set of utilities, community components to build your own features, as well as stock patches and fully custom firmware.
Alt FirmwareKlangfeld Labs
Alternative firmware for the Roland SP-404 MkII by Klangfeld Labs. Based on Roland firmware 5.52, it adds a graphical pattern sequencer, piano roll, track mixer, effect automation, custom shortcuts, and boot animations. This is an unofficial alpha release; installation uses the project's browser-based patcher and Roland's original firmware file.
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