PURPOSE: To monitor desired output data by providing an address designating device, which has switches whose number corresponds to the number of address bits of an RAM in a microcomputer, and LEDs whose number corresponds to the number of data bits.

CONSTITUTION: A microcomputer 1 reads data from a digital input circuit 2 and an analog input circuit 3 and encodes data and stores it in an RAM whose addresses are determined preliminarily. The microcomputer 1 executes the operation control of an air conditioner in accordance with a prescribed program and stores operation control data in the RAM. An address designating device 6 and a display device 7 are connected to the microcomputer 1, and data contents stored in addresses of the RAM corresponding to opening and closing of individual switches of the address designating device 6 are transferred to a register and are outputted to the display device 7 and are displayed with binaries by flickering of individual indicators.