Cart64out PCB Extender for Commodore C64

Cart64out – Diagnostic Cartridge Slot Extender/Adapter for C64

Cart64out is a simple, passive diagnostic tool for owners and developers of hardware for the Commodore 64. The PCB plugs directly into the C64 cartridge slot and routes all port signals externally, allowing you to connect a logic analyzer, oscilloscope, or other measurement equipment—without disconnecting the running system. This solves the age-old problem of debugging retro hardware "blindly": instead of guessing what's happening on the bus, you can see live signals while the cartridge continues to work normally in the computer.

Applications:

• Reverse engineering old cartridges
• Development of custom cartridge projects
• Diagnostics of the C64 expansion port
• Learning and experimenting with the 6510/6502 bus

Specifications:

• Edge connector (2.54 mm pitch) — input for the C64 slot
• Pass-through connector 2×20 pin (cartridge)
• Breakout connector 2×12 pin (measurement signal output)
• SIL resistor array 8× 10 kΩ
• Tact switch 6×6 mm (e.g., for reset)
• Fully passive design — no active electronics, no external power supply

Project Author: Stefan Eilers (Germany) — open-source project under GNU GPL license, schematics and source files publicly available on GitHub.

Project:
Cart64out - An extender for the C64 cartridge port