A step motor driving apparatus includes a micro control unit, a pulse generator, a first step motor driver, a second step motor driver, and a communication port. More specifically a network is disclosed for processing data. The peripheral device control module causes the peripheral device connected to an inputoutput interface to operate in response to the operation request received from the external apparatus. A second facet mirror of the illumination optical unit is disposed downstream of the first facet mirror and has a plurality of facets. In step S6, an IP address for a new terminal apparatus is allocated and the new terminal apparatus can participate in a homenetwork.