PURPOSE: To obviate the bit position adjustment when data is generated in a buffer memory and to simplify a processing by a microcomputer used for a printer by a method wherein distance between dot lines is determined to be an integral multiple of a dot number per access unit of the buffer memory used for the printer.

CONSTITUTION: To set a basic resolving power (n) to 300 dpi, a dot shift amount between an odd-number dot line and an even-number dot line in a line direction is determined to 1/300 inch (1/n) corresponding to the basic resolving power. As a line gap between an odd-number dot line and an even-number dot line, 64/300 inch is found by substituting N = 8 and B = 8 to the following formula : N × (B × 1/n) where N and B respectively represent an arbitrary constant and a memory access unit. In this manner, since a distance between dot lines is determined to an integral multiple of a dot number per access unit of a buffer memory used in a printer, there is no need for adjusting a bit position when data is generated in the buffer memory on a printer side.