To design an integrated circuit device, i.e., a main ASIC, that can easily be used for both communications and image data processing. To use the ASIC for the purpose of image data processing, the ASIC is set to a first operation mode, wherein a printer engine and a laser scanner are controlled via a printer engine controller and laser scanner controller. To use the ASIC for the purpose of communications, it is set to a second operation mode, wherein communications data is received from a remote device connected to a network chip via a network. In this manner, the ASICs with the same hardware configuration can be used in different purposes while switching operation modes.