PURPOSE: To improve system efficiency by storing character data in a character area when taking a copy of only necessary data among display data.

CONSTITUTION: For copying, a readout command A for indicating a read of character data CH is sent from the control part 2 of a processor 1. Consequently, the character data CH in the character area 10 of a display memory 8 are fetched by a controller 7 and sent to the processor 1 to be stored in the buffer area B of a memory 4. A discrimination part 3 discriminates the character data CH in the buffer area B to actuate the control part 2 for the generation of a copy command Cg when deciding that the copying is unnecessary, or to generate a copy command Cf when recognizing the necessity of copying. On receiving the copy command Cg, the controller 7 fetches screen data G in the screen area 9 of the display memory 8 and deletes and sends the character data in a screen area 10 to a printer 6, which prints the data.