A system that controls and operates a plurality of media processing devices can also operate devices having different specifications. A multifunction device has a roll paper print unit; a first interface that receives data from a POS terminal; a conversion unit that converts a command contained in the received data to a first executable command that is executed by the roll paper print unit, or a second executable command that is executed by a printer; a second interface that sends the converted data to the printer; and a control unit that changes between a first operating mode in which the roll paper print unit executes the first executable command, or a second operating mode in which data including the second executable command is sent by the second interface to the printer.