An mounting structure includes an enclosure, a bracket, a latching member, and an elastic member. In one aspect there is a unit having an interface for coupling to at least one peripheral unit, where each of the unit and the peripheral unit include a system on a chip. A control circuit is configured to receive a first input voltage signal and a second input voltage signal, and controlled by a sleep signal, a selection signal, and a data input signal, so that the output of the control circuit is data sensitive to the data input signal.