# GearSystem

> Gearsystem is an accurate, open source emulator for the Sega Master System, Game Gear and SG-1000, with a Z80 core that covers undocumented behaviour.

Web page: https://emulationking.com/sega/mastersystem/emulator/gearsystem/
Page updated: 2026-10-04

- Developer: Ignacio Sánchez
- Source code: https://github.com/drhelius/Gearsystem
- Supported systems: SG-1000, SEGA Master System, Game Gear
- Runs on: Windows, Linux, macOS

Gearsystem is a highly accurate, cross-platform Sega Master System emulator that also covers the Game Gear and SG-1000. It is written in C++ and is highly portable, running on Windows, Linux, macOS, Raspberry Pi and iOS.

It has a very accurate Z80 core that even implements the processor's undocumented behaviour, so games run correctly, down to their small quirks. Gearsystem supports several cartridge mappers, including standard Sega cartridges, Codemasters cartridges and simple ROM-only cartridges.

Gearsystem also has highly accurate VDP emulation, including accurate timing.

It is one of the strongest and most portable emulators available for the Sega Master System.

## Latest builds

Download these from the web page: https://emulationking.com/sega/mastersystem/emulator/gearsystem/#download

- for Windows (ARM64): 3.9.21 (2026-10-04)
- for Windows (x64): 3.9.21 (2026-10-04)
- for Linux (Ubuntu 24.04, x64): 3.9.21 (2026-10-04)
- for macOS (Intel): 3.9.21 (2026-10-04)
- for macOS (Apple Silicon): 3.9.21 (2026-10-04)