PURPOSE: To enable warming up time of a controller to be shortened by a method wherein developing operation of a font and a task in relation to receiving a data are controlled.

CONSTITUTION: A controller comes to be of a printable state by completion of self test processing after closing a power source, and sets a font rotation flag. When any printing data is not received from a host computer thereafter, a rotary font is generated by rotating a font in a ROM 13. When a printing data using the rotary font is received from the host computer before generation of the rotary font is completed, a wait flag is set. Thereafter, until generation of the rotary font is completed and the font rotation flag and the wait flag are cleared, printing process of the printing data (a command analytical processing) is restrained.