A selection menu screen for specifying if a popup function should be enabled or disabled is displayed in a setup process. The selected information in the setup process is stored in an RTC memory backed up by a battery. A CPU initiates a timer interrupt process in response to an interrupt signal from a programmable interrupt timer. At this time, the CPU refers to the RTC memory, and skips a routine for a popup process when the popup function is disabled and executes a routine for another timer interrupt process. The CPU performs the popup process only when the popup function is enabled.