Licenses
Bizmuth is proprietary software — © 2026 TwistedRaven, all rights reserved. This page acknowledges the third-party software Bizmuth is built with, and the trademarks and copyrights of the platform it emulates.
Third-party software
Bizmuth is built with the components below, with thanks to their authors. Each is used under the licence shown; the complete licence texts ship with every download as THIRD-PARTY-LICENSES.html.
z80emu LGPL Compliance
Bizmuth is proprietary, but its ZX Spectrum Next Z80 / Z80N CPU core is a modified version of z80emu (© Rafał Michalski, LGPL-3.0-or-later), so we honour the LGPL’s relinking requirement. It ships as a separate, user-replaceable shared library — z80_ffi.dll (Windows), libz80_ffi.so (Linux) or libz80_ffi.dylib (macOS), installed beside the executable — so you may rebuild it and relink it with Bizmuth, exactly as the LGPL permits.
The complete corresponding source is the unmodified upstream z80emu 0.9.0 from crates.io plus our patch (which adds the Z80N extended-opcode support and related core changes):
Our z80emu patch (tar.gz, ~6 KB)
The shipped CPU library (libz80_ffi) is that z80emu plus a small C-ABI wrapper. To build a replacement, download the z80-ffi wrapper source, place your patched z80emu 0.9.0 at ./z80emu inside it, and cargo build --release — the README in the tarball has the steps:
z80-ffi wrapper source (tar.gz, ~3 KB)
The complete LGPL-3.0 text ships with every Bizmuth download as part of THIRD-PARTY-LICENSES.html.
Emulator & tooling
| Component | Purpose | Licence |
|---|---|---|
| wxWidgets | GUI toolkit | wxWindows Library Licence (LGPL + static-linking exception) |
| wxdragon | wxWidgets Rust bindings | Apache-2.0 / MIT |
| z80emu (modified — replaceable shared library, see above) | Z80 / Z80N CPU core | LGPL-3.0-or-later |
| dez80 (vendored) | Z80 disassembler (debugger) | MIT |
| cpal | Audio output | Apache-2.0 |
| ringbuf | Lock-free audio ring buffer | MIT / Apache-2.0 |
| tokio | Async runtime (debug server) | MIT |
| Rhai | Debugger scripting | MIT / Apache-2.0 |
| smartstring | Small-string optimization (via Rhai) | MPL-2.0 |
| serde & bincode | Serialisation (save states) | MIT / Apache-2.0 |
| zstd (bundling the Zstandard C library) | Save-state compression | MIT binding / BSD-3-Clause (© Meta) |
| png | Screenshot encoding | MIT / Apache-2.0 |
| gilrs | Gamepad input | MIT / Apache-2.0 |
| clap | Command-line parsing | MIT / Apache-2.0 |
| ureq | HTTPS client | MIT / Apache-2.0 |
| rustls | TLS | Apache-2.0 / ISC / MIT |
| ring | Cryptography | ISC-style (see the project’s LICENSE) |
| webpki-roots | Mozilla CA root bundle | CDLA-Permissive-2.0 |
| zip + flate2 | Zip / DEFLATE extraction | MIT (zip) · MIT / Apache-2.0 (flate2) |
This website is built with the Zola static-site generator (its post-0.22 code is EUPL-1.2, used only as a build tool) and Bootstrap (MIT).
Trademarks & platform copyrights
Bizmuth is an independent emulator, not affiliated with or endorsed by any of the following:
- Sinclair and ZX Spectrum are trademarks of Sky plc / Amstrad, used descriptively.
- Spectrum Next and System/Next are © SpecNext Ltd. The Spectrum Next logo is copyright and is neither used nor distributed by Bizmuth.
- NextZXOS, NextBASIC, +3e, ResiDOS and IDEDOS are © Garry Lancaster, under The Next Licence.
- TBBLUE is © Victor Trucco & Fabio Belavenuto.
- All other product names and trademarks are the property of their respective owners.
ROMs, firmware & SD images
The original Sinclair 48K / 128K / +2A / +3 ROMs are © Amstrad plc. Amstrad granted permission (1999) for the ZX Spectrum ROMs to be redistributed free of charge for use with emulators — not for sale — and Bizmuth ships them as an optional ROM pack under that permission. Amstrad retains all rights.
The ZX Spectrum Next core and NextZXOS firmware are © Garry Lancaster / SpecNext Ltd under The Next Licence, which permits redistribution of the System/Next Distribution in its entirety, free of charge and not for sale. Bizmuth hosts the official System/Next SD image with only its FAT filesystem repaired (the upstream image is a malformed FAT32 that fails first boot in strict emulators) — every file is otherwise byte-for-byte identical, and The Next Licence travels inside the image at /LICENSE.md. The download also bundles tbblue_loader.rom (the 8 KB Next host bootrom, part of the Distribution). See Downloads.