Abstract: These is disclosed a printer which continues, after resumptio of power, printing which was in progress before a power failure. In this printer, the disconnection and resumption of power is detected by a detection circuit. When power is once disconnected and then restored, the presence of any character other than blanks which may have been printed by a printing head is detected in a line where the printing head is positioned. If any character other than blanks had been printed on the line where printing operation was interrupted due to disconnection of power, the printing head is controlled to print for crossing out the line after resumption of power. On the other hand, if nothing other than blanks had been printed in the line where the printing operation was interrupted, the printing head is controlled to print the same contents on the line as should have been printed on it without starting another line after resumption of power.

Abstract: A data error-checking system including a transmitting cash register and a receiving cash register, connected to each other in series in a loop formation. Its operation includes the serial transfer of data from the transmitting cash register to the receiving cash register simultaneous with data transfer from the receiving cash register to the transmitting cash register, and comparison of the data transferred from the transmitting cash register with the corresponding data transferred back from the receiving cash register to the transmitting cash register.

Abstract: A printer mounted on an electronic cash register (ECR) performs printing on printing paper by moving a print head left to right and right to left, i.e. bidirectionally. The printer uses right and left reset signals to determine the print start position and printing direction of the print head, the right and left reset signals being fed alternately and regularly to the driving circuit for the print head for performing bidirectional printing, thereby assuring correct bidirectional printing. The right and left reset signals are constantly monitored. If the reset signals of the same kinds are successively detected, it is judged that trouble has occurred, hampering correct bidirectional printing, and notice is issued accordingly.

Abstract: An electronic apparatus including a circuit generating a control signal activating at least one heavy load includes a voltage comparision circuit for comparing a power source proportional voltage with a reference voltage and outputting a power-off signal when the level of the power source proportional voltage is smaller than that of the reference voltage, and a power-off detection circuit responsive to the power-off signal of the comparision circuit for detecting the level of the control signal associated with the at least one heavy load and detecting a power-off condition of the electronic apparatus.