Mouse

This a standard 2-button ball mouse. A few 64DD games support it:

Mario Artist: Paint Studio Mario Artist: Talent Studio Mario Artist: Polygon Studio Mario Artist: Communication Kit Most other N64 games see the mouse as a controller, and a few of them are playable like this. Mouse movements register as analog stick movements. The left button maps to the A button, and the right mouse button maps to B.

There is a single microcontroller that handles everything.

This mouse appears to be based on contemporary Mitsumi ECM-S3902 PS/2 mice, which have nearly identical guts.