Libretro Gearsystem is an open source, multi-platform Sega Mark III / Master System / Game Gear / SG-1000 / Othello Multivision emulator written in C++.
- Highly accurate Z80 kernel, including undocumented opcodes and behaviours such as the R and MEMPTR registers.
- Multi-Mapper support: SEGA, Codemasters, SG-1000 and ROM cartridges only.
- Automatic region detection: NTSC-JAP, NTSC-USA, PAL-EUR. Internal database for ROM detection
- Highly accurate VDP emulation, including synchronisation and support for SMS2 mode only
- Audio emulation using SDL Audio and the Sms_Snd_Emu library
- Support for battery-powered RAM saver
- Record status * Support for VDP emulation using SDL Audio and the Sms_Snd_Emu library
- Support for VDP emulation using SDL Audio and the Sms_Snd_Emu library
- Support for battery-powered RAM saver
- Game Genie and Pro Action Replay cheat support Runs on Windows, Linux, Mac OS X, Raspberry Pi, iOS and as Libretro Core (RetroArch)
The Libretro Core Gearsystem was created by Ignacio Sanchez.
¶ 
License
This core is under GPLv3 license.
¶ 
Compatibility
| RPI0/RPI1 | RPI3 | RPI4/RPI400 | RPI5 | ODROID XU4 | OGA/OGS/RG351 | PC | RG353 |
|---|---|---|---|---|---|---|---|
| ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
¶ 
Features
| Feature | Supported |
|---|---|
| Restart | ✔ |
| Screenshots | ✔ |
| Saves | ✔ |
| States | ✔ |
| Rewind | ✔ |
| Core Options | ✔ |
| RetroAchievements | ✔ |
| RetroArch Cheats - Game Genie | ✔ |
| RetroArch Cheats - Pro Acion Replay | ✔ |
| Controls | ✔ |
| Remapping | ✔ |
| Softpatching | ✔ |
¶ 
BIOS
¶ List of optional bios
| Filename | Description | MD5 | Provided |
|---|---|---|---|
| bios_U.sms | BIOS US MasterSystem (bootrom) | 840481177270d5642a14ca71ee72844c b264bef9bda264ffe83afcebac21b81f e8b26871629b938887757a64798df6dc 02cbb2e348945c9ac41e37502a58ca76 5cd8f62cd8786af0226e6d2248279338 08b81aa6be18b92daef1b875deecf824 | ❌ |
¶ Location
Put the bios like this:
┣ 📁 recalbox
┃ ┣ 📁 share
┃ ┃ ┣ 📁 bios
┃ ┃ ┃ ┣ 📁 mastersystem
┃ ┃ ┃ ┃ ┣ 🗒 bios_U.sms
¶ 
Roms
¶ Supported extensions
Roms must have the extension:
- .sms
- .zip
- .7z
This system supports compressed roms in .zip/.7z format. However, be careful, it is only an archive.
The files contained in the .zip/.7z must correspond to the extensions mentioned above.
Moreover, each .zip/.7z file must contain only one compressed rom.
¶ Location
Put the roms like this:
┣ 📁 recalbox
┃ ┣ 📁 share
┃ ┃ ┣ 📁 roms
┃ ┃ ┃ ┣ 📁 mastersystem
┃ ┃ ┃ ┃ ┣ 🗒 game.zip
The roms using No-Intro format are highly recommended.
For more information about roms, go to this tutorial!
¶ 
Advanced configuration of the emulator
To be able to keep your custom configurations during an upgrade, we advise you to use our configuration override feature.
¶ Accessing to options
You can configure various options in two different ways.
- Via RetroArch menu:
┣ 📁 RetroArch Menu
┃ ┣ 📁 Core options
┃ ┃ ┣ 🧩 Name_option
- Via the file
retroarch-core-options.cfg:
┣ 📁 recalbox
┃ ┣ 📁 share
┃ ┃ ┣ 📁 system
┃ ┃ ┃ ┣ 📁 configs
┃ ┃ ┃ ┃ ┣ 📁 retroarch
┃ ┃ ┃ ┃ ┃ ┣ 📁 cores
┃ ┃ ┃ ┃ ┃ ┃ ┣ 🧩 retroarch-core-options.cfg
¶ Core options
| Options | Options values | Variables (for configuration override) | Variables values |
|---|---|---|---|
| System (restart) | Auto ✅ / Master System / Mark III / Game Gear / SG-1000 / Multivision |
gearsystem_system |
Auto / Master System / Mark III / Game Gear / SG-1000 / Multivision |
| Region (restart) | Auto ✅ / Master System Japan / Master System Export / Game Gear Japan / Game Gear Export / Game Gear International |
gearsystem_region |
Auto / Master System Japan / Master System Export / Game Gear Japan / Game Gear Export / Game Gear International |
| Mapper (restart) | Auto ✅ / ROM / SEGA / Codemasters / Korean / MSX / Janggun / SG-1000 |
gearsystem_mapper |
Auto / ROM / SEGA / Codemasters / Korean / MSX / Janggun / SG-1000 |
| Refresh Rate (restart) | Auto ✅ / NTSC (60 Hz) / PAL (50 Hz) |
gearsystem_timing |
Auto / NTSC (60 Hz) / PAL (50 Hz) |
| Master System BIOS (restart) | Disabled ✅ / Enabled |
gearsystem_bios_sms |
Disabled / Enabled |
| Game Gear BIOS (restart) | Disabled ✅ / Enabled |
gearsystem_bios_gg |
Disabled / Enabled |
| 3D Glasses | Both Eyes / OFF ✅ / Left Eye / Right Eye |
gearsystem_glasses |
Both Eyes / OFF / Left Eye / Right Eye |
| Allow Up+Down / Left+Right | Disabled ✅ / Enabled |
gearsystem_up_down_allowed |
disabled / enabled |
¶ 
External links
- Source code used: https://github.com/drhelius/Gearsystem/
- Libretro documentation: https://docs.libretro.com/library/gearsystem/