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.
The CPU core
The Z80 / Z80N CPU core is hg80, written by TwistedRaven and published under MIT OR Apache-2.0. hg80 contains work derived from the T80 core and its T80N modifications, redistributed under a three-clause BSD licence — see the NOTICE in its repository.
Emulator & tooling
| Component | Purpose | Licence |
|---|---|---|
| wxWidgets | GUI toolkit | wxWindows Library Licence (LGPL + static-linking exception) |
| wxdragon | wxWidgets Rust bindings | Apache-2.0 / MIT |
| hg80 | Z80 / Z80N CPU core | MIT / Apache-2.0 (derived work under BSD-3-Clause — see its NOTICE) |
| 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.