Source Code: https://github.com/zorchenhimer/keytest
This is a utility ROM that I wrote to figure out how to read the Famicom Keyboard. I also learned the specifics of the Family Trainer mat and provided some new details for the community. I’ve got more details on the Family Trainer in its own post.
So far, I only have a few peripherals implemented, but I do plan on getting a few more in there.
The standard controller test looks for the Famicom’s built-in controllers, famicom expansion controllers, as well as the NES standard controlers and controllers plugged into a Four Score.
The Hori Track is a trackball for the Famicom. The trackball is incredibly low-resolution, but it works fairly well. Only a handful of games actually use the device.