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MesenCE - RetroBIOS
Type standalone
Classification Enhanced forks
Source https://github.com/nesdev-org/MesenCE
Upstream https://github.com/SourMesen/Mesen2
Version 2.2.1
Profiled 2026-08-06
Cores mesence
Systems nintendo-nes, nintendo-fds, nintendo-snes, nintendo-satellaview, nintendo-sufami-turbo, nintendo-super-game-boy, nintendo-gb, nintendo-gbc, nintendo-gba, nec-pc-engine, nec-pc-engine-cd, nec-supergrafx, sega-mastersystem, sega-gamegear, sega-sg1000, coleco-colecovision, bandai-wswan, bandai-wswanc, pocket-challenge-v2
Platform details

firmware_folder: Firmware/ firmware_size_check: exact ui_hash_check: sha256, advisory (UI/Interop/FirmwareTypeExtensions.cs) satellaview_streams: Satellaview/BSX-.bin source_ref: Utilities/FolderUtilities.cpp:81-91, Core/Shared/FirmwareHelper.h

Technical notes

MesenCE is the community edition of Mesen2, a multi-system emulator covering NES/FDS, SNES (with Satellaview, Sufami Turbo, Super Game Boy), GB/GBC/GBA, PC Engine (including CD-ROM and SuperGrafx), SMS/Game Gear/ SG-1000/ColecoVision and WonderSwan (including Pocket Challenge V2).

All firmware is loaded from a flat /Firmware/ folder (FolderUtilities::GetFirmwareFolder, Utilities/FolderUtilities.cpp:81-91). The core enforces exact file sizes at load time (FirmwareHelper.h AttemptLoadFirmware). The UI additionally knows SHA256 values per file (UI/Interop/FirmwareTypeExtensions.cs) and warns on mismatch when importing through the firmware prompt, but a mismatched file can still be used. The sha256 values below come from that table.

SNES DSP-1/1B/2/3/4 and ST010/ST011 firmware is loaded from the combined file listed below, or from a split pair .program.rom + .data.rom (FirmwareHelper.h AttemptLoadDspFirmware). ROM dumps with the firmware appended to the game ROM need no external file (LoadDspFirmware embedded path, FirmwareHelper.h:131-135).

GB/GBC/SGB boot ROM images are compiled into the core (Core/Gameboy/GbBootRom.h:8,49,99); the external files below override them. Super Game Boy mode falls back to the plain GB core when SGB1.sfc/SGB2.sfc is missing (BaseCartridge.cpp:698-717).

Satellaview data broadcasts are read from /Satellaview/ as BSX-.bin (BsxStream.cpp:67-74). Five stream files and MesenNesDB.txt ship inside the application binary (Dependencies.zip) and are extracted to the home folder at startup; user-provided replacements are preserved (UI/Utilities/DependencyHelper.cs:14-66). NES and SNES cheat databases (CheatDb.Nes.json, CheatDb.Snes.json) are read directly from the embedded archive and never touch the filesystem (DependencyHelper.cs GetFileContent, CheatDatabaseViewModel.cs:33).

HdPacks are per-game texture/audio replacements under /HdPacks/, game content rather than system files.

35 files | 14 required, 21 optional | 24 in repo, 11 missing Categories: 29 BIOS, 6 game data

dsp1.rom required missing

dsp1b.rom required missing

dsp2.rom required missing

dsp3.rom required missing

dsp4.rom required missing

st010.rom required missing

st011.rom required missing

st018.rom required missing

BS-X.bin required in repo

SufamiTurbo.sfc required missing

SGB1.sfc optional in repo

SGB2.sfc optional in repo

dmg_boot.bin optional in repo

cgb_boot.bin optional in repo

sgb_boot.bin optional in repo

sgb2_boot.bin optional in repo

gba_bios.bin required in repo

disksys.rom required in repo

StudyBox.bin optional in repo

ymf288_adpcm_rom.bin optional in repo

lh5323m1.bin optional in repo

MesenNesDB.txt optional in repo game_data

[BIOS] Super CD-ROM System (Japan) (v3.0).pce required missing

[BIOS] Games Express CD Card (Japan).pce optional missing

bios.sms optional in repo

bios.gg optional in repo

bios.col required in repo

bootrom.ws optional in repo

bootrom.wsc optional in repo

bootrom_sc.wsc optional in repo

BSX0120-0.bin optional in repo game_data

BSX0121-0.bin optional in repo game_data

BSX0122-0.bin optional in repo game_data

BSX0123-0.bin optional in repo game_data

BSX0124-0.bin optional in repo game_data

Generated on 2026-08-23T16:12:06Z