A reader controller is connected to a printer controller which controls a engine controller provided in a printer. The printer includes a controlling unit for controlling a document reader which reads documents, a receiving unit for receiving a command for the engine controller from the printer controller, and a counting unit for counting a number of documents processed by the reader controller in accordance with a control of the controlling unit, and counting a number of sheets processed by the printer controller in accordance with the command received by the receiving unit. The printer further includes a causing unit for causing a display of the reader to display the number counted by the counting unit.