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# SMS Plus GX - RetroBIOS

Type | standalone + libretro
Classification | enhanced_fork
Source | https://github.com/libretro/smsplus-gx
Upstream | https://github.com/ekeeke/smsplus-gx
Version | 1.8
Profiled | 2026-03-25
Cores | smsplus
Systems | sega-master-system, sega-game-gear, colecovision, sega-sg1000, sord-m5

Technical notes

Enhanced fork of Charles MacDonald's SMS Plus 1.3 by Eke-Eke (GX) and gameblabla. Master System, Game Gear, ColecoVision and SG-1000 emulator. Standalone ports also support Sord M5 (behind SORDM5_EMU compile flag, not compiled in libretro build).

BIOS loading in bios_init() (smsplus_libretro.c:203-252). bios.sms is always attempted but only activated when core option smsplus_sms_bios is "auto" (default: disabled). BIOS.col is loaded only for ColecoVision ROMs and required for them. Standalone ports use BIOS.sms (uppercase) instead of bios.sms.

.info marks BIOS.col as optional (firmware1_opt=true) but the libretro code returns false from retro_load_game() when BIOS.col is missing for .col ROMs.

3 files | 1 required, 2 optional | 2 in repo, 1 missing

`bios.sms` -optional : Sega Master System boot ROM

- System: sega-master-system
- Aliases: `BIOS.sms`
- Source: `smsplus_libretro.c:211-229`
- Platforms: lakka, retroarch, retrodeck, retropie
- Loaded into bios.rom (up to 1 MB allocated). Only active when core option smsplus_sms_bios is "auto". Displays SMS startup screen before game execution. Standalone ports use BIOS.sms (uppercase).

`BIOS.col` -required : ColecoVision BIOS ROM

- System: colecovision
- Size: 8.0 KB
- Source: `smsplus_libretro.c:232-248`
- Platforms: lakka, retroarch, retrodeck, retropie
- Required for ColecoVision games. Read as 0x2000 (8192) bytes into coleco.rom. Without this file, retro_load_game() returns false for .col files.

`BIOS_sordm5.bin` -optional, standalone, missing from repo : Sord M5 BIOS ROM

- System: sord-m5
- Size: 8.0 KB
- Source: `ports/sdl/smsplus.c:321-329`
- Read as 0x2000 (8192) bytes into coleco.rom (shared buffer). Only in standalone builds (SORDM5_EMU define). Not compiled in libretro. Code does not enforce presence but system needs BIOS to function.

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