To directly and smoothly execute data update on a duplication volume while suppressing a load on a master volume, when performing backup by employing the snapshot system. The display device includes first, second, and third touch-control structures, a first plate, and a second plate opposing the first plate. The optical disc apparatus acquires spindle output for the spindle motor during the CLV control, and calculates an average value of the acquired spindle output, and further stores the calculated average value. The prosthetic is attachable and removable without the discomfort, cost, risks, or permanence of a surgical procedure. The radio module is adapted to 1) pass messages received via the interface to the GPS receiver via an internal interface, and 2) to receive messages from the GPS receiver via an internal interface and pass them further to the external interface.