A transition of an external enable signal generates a reset pulse to a counter to set the counter into a known state. Further, when an @ mark is input after a character string input, the information displayed on the second display is switched to a domain name read from the domain name registration area. The impact arm may be an impact spoon formed on an impact disc. Accordingly, the system is always maintained at an optimum state. This nickel vanadium barrier protects the gallium arsenide substrate from the diffusion effects of the copper contact layer.