A troubleshooting tool to determine the cause of your old treasure not starting properly. Be it a black startup screen, no sound, random characters on the screen, garbled output or broken components.

When repairing or restoring old 64s, these two cartridges are invaluable. Not a single repair job goes ahead without using either or both cartridges.

Using a double-sided cartridge is handy as both tests are directly at hand, with no ruffling and scrounging around the desk to find the other cartridges. The cartridge also includes a reset button if needed.

Note: The diagnostic cartridge requires a testing harness to complete all tests. It works without it but cannot test user, tape, serial or joystick ports.

The cartridge does not come with a case. You can find a 3D printable case like the MagicDesk Dual Case on Thingiverse.

All units have been tested in short- and longboard versions of the C64.