The invention provides a circuit that can observe data within shift registers without altering the data. In some forms, each connector attaches a single supported member. The second female end is provided with of spaced-apart through-slots or opening for receiving therethrough a pair of forks or leg-sections of a yoke. The beam interchanging and image inverting system supplies a first beam bundle directed to the left from the object plane in the direction of the objective system to the right of the objective system. The first listener may also create a playlist of the listening experiences in the library and make the playlist available to others.