Control data is stored in a first memory. Control data inputted from an external device is stored a second rewritable memory. A control section selects either one of the first and second memories and controls operation according to a control program using the control data stored in the memory selected. An image corresponding to control data is displayed on a display screen. Through the image, it is possible to select particular control data from a plurality of control data. The control data selected via the screen is sent to the second memory. Processing can be therefore executed to appropriately cope with requirements of the user.