# Licensing and provenance

MC-1 is GPL-3.0-only; the complete license is in LICENSE.
New engine, sequencer, project format, UI, host harness, presets and mathematical assets:
Copyright (C) 2026 dspaudio. These are original implementations, not copies of Roland sound algorithms or content.

The following files were copied from the **public** dspaudio/orbit repository at commit
`07e3fed30e8e6757dbe3c6810276599987e4970e` and retain their original GPL-3.0-only notices:

- `firmware/hal/fm1_*.h`, `firmware/hal/fm1_isr.S`, `firmware/hal/fm1_vec.S`
- `firmware/crt0.S`, `firmware/app.ld`, `firmware/lcd.c`, `firmware/libc.c`
- `firmware/loader/*`, `firmware/update/*`, `tools/fm1pkg_make.py`, `tools/lz4blk.py`,
  `tests/ldr_test.c`; loader wrapping in `tools/build_package.py` is adapted from upstream `tools/build.py`.
- `firmware/connection/midi_uart.c` and `tests/connections.c` adapt the upstream
  TRS MIDI parser and USB Audio/UART tests. `firmware/hal/fm1_uart.h` supplies
  the inherited UART register mapping. MC-1 adds application routing and USB identity.

Copyright (C) 2026 Leo Kuroshita (@kurogedelic), Hügelton Instruments.
The lineage is ORBIT → SLOOP → Felucca; ORBIT identifies SLOOP origin commit
`d691ba7b2d922f1a1f41a3622cffe29ce41c5506` and subsequent upstream integrations.
Upstream source: https://github.com/dspaudio/orbit/tree/07e3fed30e8e6757dbe3c6810276599987e4970e

Hardware, startup, LCD-transfer, freestanding libc and update-loader infrastructure are reused.
The encoder acceleration thresholds are inspired by the GPL ORBIT `ui_input.c` at
the same commit: ranges above 40 use 3× within 60 ms, or 6× above 150. MC-1 adds
first-input, direction/context reset and shared host/device timing behavior.
MC-1 does not include ORBIT engines, tape workflow, sequencer, sample banks, patch assets,
restricted Felucca icons, panel photos, Hügelton Sample Pack, proprietary Roland ROMs,
PicoFaceJV ROMs, Munt code, Open303 code or DaisySP code.

## Browser firmware installer

`site/firmware-ota.js` ports the public `tools/fm1_install.py` at the ORBIT
commit above. The audited Python source is 19402 bytes, SHA256
`987f3203c4575d82c4234217964f2f5e7e7cbf41ad277154c378bc9433a244f9`.
Copyright (C) 2026 Leo Kuroshita (@kurogedelic), Hügelton Instruments;
GPL-3.0-only. Copyright (C) 2026 dspaudio covers the JavaScript port, package
and SHA256 checks, bounded Web MIDI transport, event-driven reconnection,
installer UI and tests. Original notices remain in the source files.
The installer and checked MC-1 release package are served together by this
repository's Pages site. The corresponding source is available at its release
tag. `FM-1_900` and `FELUCCA-LOADER-1` are protocol identifiers, not MC-1 version
claims. Package SDK assets retain the licenses described below.

## Sensing reference audit — excluded from this release

The earlier velocity/aftertouch investigation examined
`charlesvestal/fm1-monk` commit `8af3c3d91d51194cf5f5259da3327033db90deb4`:
https://github.com/charlesvestal/fm1-monk/tree/8af3c3d91d51194cf5f5259da3327033db90deb4
Its root LICENSE contains GPL version 3. The sensing source
`firmware/src/app/sense.c` explicitly carries `GPL-3.0-only` and does not name
a separate copyright holder in its header. Its `firmware/hal/fm1_input.h`
also carries `GPL-3.0-only` and the original Leo Kuroshita/Hügelton Instruments
notice quoted above. These existing notices must be retained verbatim in any
adapted files; new adaptation notices must identify MC-1's changes and date
without inventing authorship of upstream work.

Physical sensing and pressure modulation were removed from this release's scope.
No code from this reference has been imported into the current MC-1 build.
This audit does not assert that unrelated MONK-1 DSP, artwork, fonts, or other
dependencies are included or have all been audited. The actual imported file
list and modifications must replace this reference-only entry if a future
release imports that code.

## Original assets and recorded samples

`src/tables.h` is generated by `tools/gen_assets.py`: additive waveform tables, sine/tuning
and 24 original short deterministic attacks. These assets, demo compositions and original
bitmap font glyphs are GPL-3.0-only. Screenshots depict the original MC-1 UI.

The 16 retained instrument recordings in `assets/recorded/` and their converted PCM
arrays in `src/recorded_pcm.h` are CC0-1.0, from VSCO 2 Community Edition by
Sam Gossner and Simon Dalzell, with sample cutting by Elan Hickler/Soundemote.
Source commit: `440300901dfe9275fd84e0b7763af1f8443ae62e`. The manifest records
individual source URLs, SHA-256 hashes and SFZ pitch keycenters. See
`LICENSES/CC0-VSCO.txt`; `tools/gen_recorded_pcm.py` reproducibly converts the
retained source WAVs offline. The CC0 sample license does not change the GPL-3.0-only
license of the code, original patches or generated mathematical assets.

The JieLi compiler and SDK are external build dependencies, absent from the source tree.
Experimental `.fwsc` packages include three Apache-2.0 SDK assets (`uboot.boot`,
`cfg_tool.bin`, `cfg/eq_cfg_hw.bin`) from the official JieLi AC79 SDK commit
`d179b4484759423312073f5fbb232501aa491047`, tag `AC79NN_SDK_V1.2.1_2023-12-13`:
https://gitee.com/Jieli-Tech/fw-AC79_AIoT_SDK
Their hashes are pinned in `tools/build_package.py` and the package report. See
`LICENSES/Apache-2.0-AC79.txt` for the SDK license. The included bootloader head is
package metadata: the inherited RAM update loader never writes flash below 0x4000.
The protocol identity FM-1_900 and FELUCCA-LOADER-1 marker are retained for updater
compatibility. They do not change product branding. The MC-1 audio application
also links inherited USB audio/MIDI and Felucca OTA transport code. Its OTA entry
path stages the RAM installer in the separately guarded `0xe0000..0xe4fff` range;
the RAM installer performs the application update.

Roland, MC-303, TB-303, TR-808, MT-32, M-VAVE and FM-1 names identify inspirations or target
hardware. Their owners do not sponsor or endorse MC-1. No original tone/patch compatibility
is intended. Bluetooth and Wi-Fi are not enabled.