dos-mcp

Small MCP tools for a loopback-only DOSBox-X QMP server. Ghidra's maintained GDB TraceRMI agent owns debugger state; this server supplies emulator control, paced keyboard input, bounded memory reads, screenshots, and snapshots.

Tools

• dosbox_status, dosbox_pause, dosbox_resume, and dosbox_reset
• dosbox_swap_floppy
• dosbox_send_keys, dosbox_key_event, and dosbox_type_text
• dosbox_break_on_next_exec
• dosbox_read_memory and dosbox_capture_screen
• dosbox_save_state and dosbox_load_state

Inline memory responses are capped at 4 KiB and returned as hex. Reads up to 64 KiB can instead be written to an absolute output_path. Typed text is paced and capped at 128 US-ASCII characters; it is convenient shell input, not a cycle-deterministic keyboard primitive. Use dosbox_key_event to hold and release keys. The guest must actively consume its BIOS keyboard ring while text is sent; a busy program can silently lose input. State paths must be absolute ASCII paths, and saves do not replace an existing file unless overwrite=true.

Input, reset, state, and capture operations require running execution. QMP memory reads default to requiring a paused emulator because a running read can be torn; allow_running=true opts into that explicitly. QMP pause can be resumed through dosbox_resume; a GDB stop must be continued through GDB. DOSBox-X zero-fills unreadable physical addresses, so an unmapped byte cannot be distinguished from a real zero through this QMP interface. dosbox_swap_floppy advances the pre-mounted image list for A: or B: without injecting a host-side keyboard shortcut.

Each tool call opens one local QMP session, completes the QMP handshake, performs its commands serially, and disconnects. Requests are never retried: a timed-out mutation may already have happened, so inspect emulator state before repeating it.

This server requires the companion DOSBox-X build made with --enable-remotedebug and configured with [dosbox] qmpserver=true. DOSBox-X accepts one QMP client at a time; do not attach another monitor while using this MCP server.

Configuration

The server uses 127.0.0.1 and never accepts a remote QMP host.

• DOSBOX_X_QMP_PORT defaults to 4444.
• DOSBOX_X_QMP_TIMEOUT defaults to 35 seconds.

Run with:

uv run dos-mcp

Apache-2.0.