A method for forming through hole vias in a substrate uses a partially exposed seed layer to plate the bottom of a blind trench formed in the front side of a substrate. A controller is characterized by supplying power from an auxiliary power supply to a sound signal processing unit in the standby through mode. The replacement processing is accomplished by writing stored data in a first memory area in which rewriting is relatively infrequent into an unused second memory area, and making the second memory area into which the writing has been done a used area in place of the first memory area.