PURPOSE: To make it almost unnecessary that a microprocessor participates in printing, by constituting so that a data edited by hardware after a data has been written in a line buffer.

CONSTITUTION: Data of line buffers 103, 104 are latched once by pin data registers 105, 106, respectively, and after that, are transferred to a pin driver. This data transfer is executed by a clock of a timer 107. In this case, one flow of address counters 101, 102 of the buffers 103, 104, the buffers 103, 104, and the registers 105, 106 is entirely separated by odd pin use and even pin use of print pins which have been arrayed in zigzag. Therefore, a microprocessor writes a data in the buffers 103, 104, and after that, for instance, if it has set an initial value of (i) of the counter 101, it sets a value of (i)+24 which has added 24 to said value, to the counter 102. Subsequently, when an operation start instruction is given to a timer 107, the microprocessor does not participate in the operation thereafter.