a plurality of letter output devices are connected to a letter data control device by a transmission path . the control device stores letter data for transmission to the letter output devices , and is able to convert that letter data to a desired layout and then transmits the converted letter data to one or more of the letter output devices . the control device is able to select part of its stored letter data for transmission so that only commonly used letter data need be transmitted during start up of the system . since a large amount of letter data may be stored in the control device , and only part may be transmitted to the letter output devices , those output devices can have a relatively small memory .