Geargrafx

Geargrafx is a very accurate, cross-platform TurboGrafx-16 / PC Engine / SuperGrafx / PCE CD-ROM² emulator written in C++ that runs on Windows, macOS, Linux, BSD and RetroArch, with an embedded MCP server for debugging and tooling.

This is an open source project with its ongoing development made possible thanks to the support by these awesome backers. If you find it useful, please consider sponsoring.

Don't hesitate to report bugs or ask for new features by opening an issue.

Downloads

Notes:

• Windows: May need Visual C++ Redistributable and OpenGL Compatibility Pack
• Homebrew: If Homebrew asks you to trust the third-party tap, run brew trust --tap drhelius/geardome
• Linux: May need libsdl3

Features

• Accurate emulation supporting the entire HuCard PCE / SGX catalog.
• Support for CD-ROM², Super CD-ROM² and Arcade CD-ROM² systems.
• Save states with preview and rewind support.
• Backup RAM and Memory Base 128 support.
• Multi Tap (up to 5 players).
• Standard Gamepad (2 buttons), Avenue Pad 3 (3 buttons, auto-configured based on game), Avenue Pad 6 (6 buttons) and Mouse.
• Adjustable scanline count (224p, 240p or manual).
• RGB or Composite color output with optional LPF filter.
• Compressed ROM and CD image support (pce, sgx, cue, zip and chd).
• Support for playing physical CD-ROM discs.
• Music ROM support: HES.
• VGM recorder.
• Internal database for automatic ROM detection and hardware selection if Auto options are selected.
• Supported platforms (standalone): Windows, Linux, BSD and macOS.
• Supported platforms (libretro): Windows, Linux, macOS, Raspberry Pi, Android, iOS, tvOS, webOS, 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 JSR double clicking), debug symbols, automatic labels, memory editor, PSG inspector and video viewer including registers, tiles, sprites, backgrounds, CD-ROM sub-systems and both VDCs in SuperGrafx mode.
• MCP server for AI-assisted debugging with GitHub Copilot, Claude, Codex and similar, exposing tools for execution control, memory inspection, hardware status, rewind and more.
• Windows and Linux Portable Mode.
• Programmable Shader Chain.
• ROM loading from the command line by adding the ROM path as an argument.
• ROM loading using drag & drop.
• Support for modern game controllers through gamecontrollerdb.txt file located in the same directory as the application binary.

Tips

Basic Usage

• BIOS: Geargrafx requires a BIOS to run CD-ROM games. It is possible to load any BIOS but the System Card 3.0 with md5 38179df8f4ac870017db21ebcbf53114 is recommended.
• CD-ROM Images: Geargrafx supports chd, zipped and unzipped cue/bin, cue/img and cue/iso images. cue/iso + wav is also supported when audio track format is 44100Hz, 16 bit, stereo. It does not support MP3 or OGG audio tracks.
• Mouse Cursor: Automatically hides when hovering over the main output window or when Main Menu is disabled.
• Portable Mode: Create an empty file named portable.ini in the same directory as the application binary to enable portable mode.

Debugging Features

• Docking Windows: In debug mode, you can dock windows together by pressing SHIFT and dragging a window onto another.
• Multi-viewport: In Windows or macOS, you can enable "multi-viewport" in the debug menu. You must restart the emulator for the change to take effect. Once enabled, you can drag debugger windows outside the main window.
• Single Instance: You can enable "Single Instance" in the Emulator menu. When enabled, opening a ROM while another instance is running will send the ROM to the running instance instead of starting a new one.
• Debug Symbols: The emulator automatically tries to load a symbol file when loading a ROM (.sym, .lbl, .noi). For example, for path_to_rom_file.rom it tries to load path_to_rom_file.sym. You can also load symbol files using the GUI or the CLI. It supports PCEAS (old and new format), wla-dx and vasm file formats.

Command Line Usage

geargrafx [options] [game_file] [symbol_file]

Arguments:
  [game_file]              Game file: accepts ROMs (.pce, .sgx, .hes), CUE (.cue) or ZIP (.zip)
  [symbol_file]            Optional symbol file for debugging

Options:
  -f, --fullscreen         Start in fullscreen mode
  -w, --windowed           Start in windowed mode with menu visible
      --mcp-stdio          Auto-start MCP server with stdio transport
      --mcp-http           Auto-start MCP server with HTTP transport
      --mcp-http-port N    HTTP port for MCP server (default: 7777)
      --headless           Run without GUI (requires --mcp-stdio or --mcp-http)
  -v, --version            Display version information
  -h, --help               Display this help message

MCP Server

Geargrafx includes a Model Context Protocol (MCP) server that enables AI-assisted debugging through AI agents like GitHub Copilot, Claude, Codex and similar. The server provides tools for execution control, memory inspection, breakpoints, disassembly, hardware status, rewind and more.

For complete setup instructions and tool documentation, see MCP_README.md.

Agent Skills

Geargrafx provides Agent Skills that teach AI assistants how to effectively use the emulator for specific tasks:

• geargrafx-debugging — Game debugging, code tracing, breakpoint management, hardware inspection, and reverse engineering.
• **[geargrafx-ro