Whereas, looking at the documentation (pdf file) for the original AMX mouse, left and right buttons seem to have been arranged/used confusingly. There's a strange drawing that looks as if the Right Button is used as Execute Button... ie. much like PC mouse in left-handed mode?
Although, the drawing is top-down, so the right button is actually on the left side in the drawing... though I guess that wasn't the way how one should use the mouse, with the buttons & cable pointing towards the user? :-)
Regarding: * Note: The above "1/300s" timing would be the ideal value (the existing [[AMX Mouse]] software reads the joystick port inputs at 300HZ rate). The real [[AMX Mouse]] interface, and this DIY project may not exactly match that timings.
I've removed this sentence because, if you'd gone to the bother of building the circuit, you'd know that the statement is completely untrue, or what are the facts that you base this claim on?