Abstract: There is disclosed a printer, comprising a print unit for printing on a print medium; a print media reversal unit for reversing the print medium to allow double-sided printing onto the print medium; a memory unit for storing printer configuration data, the printer configuration data including data specifying whether or not the printer is permitted to operate in a double-sided printing mode; an input device for receiving an instruction to permit the operation of the printer in a double-sided printing mode; and a print controller for controlling the print unit and the print media rotation unit, the controller being programmed to operate the printer in either a single-sided or double-sided mode in dependence on the printer configuration data, and to update the printer configuration data appropriately in response to receiving the instruction to permit the operation of the printer in a double-sided printing mode.