Geargrafx MCP — Use Cases, Install & Live Demo

Why use it

Key features

Embedded MCP server for AI-assisted debugging via stdio or HTTP transport
Full debugger: JIT disassembler, CPU/memory breakpoints, code navigation
Supports HuCard, SuperGrafx, and CD-ROM² formats (pce, sgx, cue, zip, chd)
Multi Tap support for up to 5 players with various controller types
VGM recording and save states with preview images

Live Demo

What it looks like in practice

geargrafx-2.replay ▶ ready

0/0

Install

Pick your client

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "geargrafx-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Geargrafx"
      ]
    }
  }
}

Open Claude Desktop → Settings → Developer → Edit Config. Restart after saving.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "geargrafx-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Geargrafx"
      ]
    }
  }
}

Cursor uses the same mcpServers schema as Claude Desktop. Project config wins over global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "geargrafx-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Geargrafx"
      ]
    }
  }
}

Click the MCP Servers icon in the Cline sidebar, then "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "geargrafx-2": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Geargrafx"
      ]
    }
  }
}

Same shape as Claude Desktop. Restart Windsurf to pick up changes.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "geargrafx-2",
      "command": "TODO",
      "args": [
        "See README: https://github.com/drhelius/Geargrafx"
      ]
    }
  ]
}

Continue uses an array of server objects rather than a map.

~/.config/zed/settings.json

{
  "context_servers": {
    "geargrafx-2": {
      "command": {
        "path": "TODO",
        "args": [
          "See README: https://github.com/drhelius/Geargrafx"
        ]
      }
    }
  }
}

Add to context_servers. Zed hot-reloads on save.

claude mcp add geargrafx-2 -- TODO 'See README: https://github.com/drhelius/Geargrafx'

One-liner. Verify with claude mcp list. Remove with claude mcp remove.

Use Cases

Real-world ways to use Geargrafx

How to debug a PC Engine ROM with AI assistance using Geargrafx

👤 PC Engine homebrew developers and retro game researchers ⏱ ~30 min intermediate

When to use: You're developing or analyzing a PC Engine ROM and need to debug runtime behavior.

Prerequisites

Geargrafx built with MCP support — Build from source following the GitHub README
A PC Engine ROM file (.pce or .sgx) — Your own homebrew ROM or a ROM you legally own

Flow

Connect and inspect

Connect to the Geargrafx MCP server. Show me the current HuC6280 CPU state and disassembly at the program counter.✓ Copied

→ CPU registers and disassembled instructions
Analyze sprite system

Inspect the VDC sprite table. How many sprites are active and what tiles do they reference?✓ Copied

→ Sprite attribute table with positions, tile indices, and flags

Outcome: Understanding of ROM execution and VDC hardware state for debugging.

Pitfalls

CD-ROM games require proper CUE/BIN setup — Ensure your CUE file paths are correct and all BIN tracks are present

Combine with: filesystem

Learn PC Engine hardware architecture interactively

👤 Students and enthusiasts learning retro console hardware ⏱ ~45 min advanced

When to use: You want to understand the HuC6280 CPU, VDC graphics, and PSG audio systems.

Prerequisites

Geargrafx with MCP server — Build from source

Flow

Explore the VDC

Step through the VBlank interrupt and explain how the PC Engine's VDC handles background scrolling and sprite rendering.✓ Copied

→ Annotated explanation of VDC register writes and their effects

Outcome: Hands-on understanding of PC Engine hardware internals.

Pitfalls

SuperGrafx has two VDCs which complicates analysis — Start with regular PC Engine games before tackling SuperGrafx titles

Combinations

Pair with other MCPs for X10 leverage

geargrafx-2 + filesystem

Export debug data and memory dumps for documentation

Dump the VDC sprite table and tile data to files for analysis.✓ Copied

Tools

What this MCP exposes

Tool	Inputs	When to call
pause/resume/step	none / step_count?	Control emulator execution
read_memory	address: int, size: int	Read emulator memory at any address
set_breakpoint	address: int	Set a CPU breakpoint
disassemble	address: int, count: int	Disassemble HuC6280 instructions
get_hardware_status	none	Get VDC, VCE, and PSG register states

Cost & Limits

What this costs to run

API quota: N/A — fully local
Tokens per call: 100–500 tokens per debug command
Monetary: Free and open source (MIT license)
Tip: Use targeted reads instead of full memory dumps.

Security

Permissions, secrets, blast radius

Credential storage: N/A

Data egress: Fully local — no network calls

Troubleshooting

Common errors and fixes

MCP server not responding

Ensure Geargrafx was built with MCP support. Check the default port is available.

Verify: Test the HTTP endpoint

CD-ROM game won't load

Verify CUE file references correct BIN paths. Try converting to CHD format.

Verify: Check CUE file contents match actual BIN filenames

SuperGrafx ROM crashes

Only a handful of SuperGrafx games exist. Verify the ROM is actually an SGX title, not a regular PCE ROM.

Verify: Check ROM header

Alternatives

Geargrafx vs others

Alternative	When to use it instead	Tradeoff
Gearboy	You want to debug Game Boy ROMs instead of PC Engine	Different console, same MCP-enabled emulator approach

More

Resources

📖 Read the official README on GitHub

🐙 Browse open issues

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