PURPOSE: To enable manual insertion somewhere while a printing is performed with a paper being fed from a cassette by providing a means of directing manual insertion of a printing paper at the control section of a print out unit.

CONSTITUTION: As a printing data is being transferred to a control section 20 of a print out unit from an electronic computer body, a microcomputer checks the code of the data. The microcomputer recognizes the ESC code of the data 304, then recognizes that the subsequent data is (a), which means the specification of manual insertion. When recognizing that the insertion command is given by data 304 and 305, the microcomputer controls a mechanism section and flashes a lamp for insertion of a paper for manual insertion at an operation panel of the print out unit body 1. The flashing of the lamp goes OFF when an insertion detecting switch 17 for manual insertion papers turns ON.