This adapter allows the connection of a SNES Controller to the user port of many Commodore 8-bit machines. It connects to the user port of any Commodore Pet, 64, Vic-20 or Plus 4. The adapter was designed for use with Attack of the PETSCII Robots, but other games are under development which may use this adapter in the future or you could design your own.
Games that use this adapter (more to come):
Attack of the PETSCII Robots by The 8-Bit Guy
More about the adapter:
The audio jack is for use with the Commodore Pet and amplified speakers. This jack is connected to the internal piezo speaker (if present) and will work with other games which support sound.
A single jumper is installed on the bottom of the adapter to allow connection to an external power source. Some Pets do not provide power on the user port and will need it provided from either the cassette port or externally. Instructions are printed on the bottom of the board on how to connect power if needed. All other Commodore machines work with the jumper as provided.
Please note that the user port is rated to provide 100ma of power at 5 volts. For most SNES controllers, this will be fine. If you have a third-party controller with a high current draw, it would be a good idea to provide external power.
More information is available in this video describing the pinout: https://www.youtube.com/watch?v=6xIy0Ns0jSY