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# Gearlynx - RetroBIOS

Type | libretro
Classification | official_port
Source | https://github.com/drhelius/Gearlynx
Version | 1.0.0
Profiled | 2026-03-23
Cores | gearlynx
Systems | atari-lynx
Verification mode | existence

Technical notes

Gearlynx is an Atari Lynx emulator by Ignacio Sanchez (drhelius). The libretro core loads lynxboot.img from the system directory at retro_load_game time (libretro.cpp:105-129, function load_bootroms). Path is built as: system_directory + "/lynxboot.img", no subdirectory.

LoadBios in media.cpp:274 reads exactly 512 bytes (GLYNX_BIOS_SIZE = 0x200, defines.h:52). If the file size is not 0x200, the load is rejected with BIOS_LOAD_INVALID_SIZE. After loading, bytes at offset 0x1F8 and 0x1F9 are patched (RAM/MAPCTL registers), then CRC32 is computed and compared against GLYNX_DB_BIOS_CRC (0x0D973C9D, game_db.h:38). An invalid CRC triggers a warning log but the BIOS is still marked as loaded (m_is_bios_loaded = true).

No HLE fallback. If the BIOS is not loaded (IsBiosLoaded() returns false), RunToVBlank in gearlynx_core_inline.h:31-37 renders a static "no bios" image and returns false, refusing to emulate. The BIOS is required for any ROM to run. Homebrew (.o, BS93 format) bypasses the normal boot sequence via PrepareForHomebrew() but still requires the BIOS to be loaded for the emulation loop to execute.

ROM extensions: .lnx, .lyx, .o

1 files | 1 required, 0 optional | 1 in repo, 0 missing

`lynxboot.img` -required, World : Atari Lynx boot ROM

- Size: 512 B
- SHA1: `e4ed47fae31693e016b081c6bda48da5b70d7ccb`
- MD5: `fcd403db69f54290b51035d82f835e7b`
- CRC32: `0d973c9d`
- Validation: size, crc32
- Source: `libretro.cpp:105-129 (load_bootroms), media.cpp:274-329 (LoadBios), defines.h:52 (GLYNX_BIOS_SIZE=0x200), game_db.h:38 (GLYNX_DB_BIOS_CRC=0x0D973C9D), gearlynx_core_inline.h:33-37 (no-bios guard)`
- Platforms: batocera, lakka, recalbox, retroarch, retrobat, retrodeck, retropie
- 512-byte boot ROM validated by CRC32 after load. Invalid CRC logs a warning but still works. Missing or wrong-size file blocks emulation entirely (no HLE fallback).

Generated on 2026-03-25T14:56:43Z