Boytacean - RetroBIOS¶
| Type | libretro |
| Source | https://github.com/joamag/boytacean |
| Version | 0.10.13 |
| Profiled | 2026-03-18 |
| Cores | boytacean |
| Systems | nintendo-gb, nintendo-gbc |
No BIOS or firmware files required. This core is self-contained.
Boytacean is a Game Boy / Game Boy Color emulator written in Rust by Joao Magalhaes. No external BIOS or boot ROM files are needed.
The core ships with multiple boot ROMs compiled directly into the binary as static byte arrays in src/data.rs. For DMG mode the default is "DMG Bootix" (an open-source boot ROM forked from SameBoy's Bootix project, 256 bytes). For CGB mode the default is "CGB Boytacean" (a custom open-source CGB boot ROM, 2304 bytes). The original Nintendo DMG, SGB, and CGB boot ROMs are also embedded as static arrays (DMG_BOOT, SGB_BOOT, CGB_BOOT) but the defaults use the open-source replacements.
The libretro frontend (frontends/libretro/src/core.rs) calls instance.load(true) in retro_load_game(), which routes through load_dmg() or load_cgb() depending on the cartridge header. These call load_boot_static() which copies one of the embedded byte arrays into MMU memory. There is no RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY call, no filesystem access for boot ROMs, and no core option to load external boot ROM files.
The .info file (boytacean_libretro.info) lists no firmware entries.
Boot ROM selection defaults: - DMG: BootRom::DmgBootix (gb.rs:1389) - open-source, 256 bytes - CGB: BootRom::CgbBoytacean (gb.rs:1398) - open-source, 2304 bytes
All boot ROM source code lives in src/boot/, forked from SameBoy and assembled with rgbds. The compiled binaries are then converted to Rust const arrays in data.rs.
Generated on 2026-03-18T17:30:32Z