Gearsystem is a very accurate, cross-platform Sega Master System / Game Gear / SG-1000 emulator written in C++ that runs on Windows, macOS, Linux, BSD and RetroArch.
* Accurate Z80 core, including undocumented opcodes and behavior like R and MEMPTR registers.
* Supported cartridges: ROM, ROM + RAM, SEGA, Codemasters, Korean, MSX + Nemesis, Janggun, SG-1000.
* Automatic region detection: NTSC-JAP, NTSC-USA, PAL-EUR.
* Accurate VDP emulation including timing and Master System 2 only 224 video mode support.
* Internal database for rom detection.
* Sound emulation using SDL Audio and Sms_Snd_Emu library.
* Battery powered RAM save support.
* Save states.
* Compressed rom support (ZIP).
* Game Genie and Pro Action Replay cheat support.
* Supported platforms (standalone): Windows, Linux, BSD, macOS, Raspberry Pi and iOS.
* Supported platforms (libretro): Windows, Linux, macOS, Raspberry Pi, Android, iOS, tvOS, PlayStation Vita, PlayStation 3, Nintendo 3DS, Nintendo GameCube, Nintendo Wii, Nintendo WiiU, Nintendo Switch, Emscripten, Classic Mini systems (NES, SNES, C64, ...), OpenDingux, RetroFW and QNX.
* Full debugger with just-in-time disassembler, cpu breakpoints, memory access breakpoints, code navigation (goto address, JP JR and CALL double clicking), debug symbols, memory editor, IO inspector and VRAM viewer including tiles, sprites, backgrounds and palettes.
* Windows and Linux Portable Mode by creating a file named portable.ini in the same directory as the application binary.
* Support for modern game controllers through gamecontrollerdb.txt file located in the same directory as the application binary.