A graphics processing unit is designed to have validation logic utilizing a reduced memory space shadow memory as a source of state information for performing validation of commands. Implies the determination of the quality of communication between all transceivers and storage of communication quality data by each of the transceivers. Therefore, it becomes possible to prevent moisture and oxygen outside of the display device from entering inside of the display device through an insulating film and the like including a hygroscopic organic material. A single-process poly-silicon bipolar transistor having a base produced by epitaxis in accordance with the invention permits a reduction in external base resistance without causing a deterioration in emitter properties. The parallel-arm-side IDT electrode is a normal IDT electrode in which the overlap width is constant.