READER OF PUNCHED TAPE

摘要

PURPOSE:To prevent a malfunction due to the double reading, by setting an FF at the rear edge of a rise differential pulse of a sprocket signal, resetting the FF when all signals of a data do not exist any more and making the differential pulse pass in the reset mode of the FF. CONSTITUTION:The data signals of 8 data lines supplied from a punched tape reader 2 are supplied to an OR gate 4 and a data reading circuit 7. At the same time, a sprocket signal 10 given from the reader 2 is applied to a sprocket rise differential pulse generating circuit 3 to produce a rise differential pulse 100 at the rise time of the sprocket. This pulse 100 is supplied to an FF5 and an AND gate 6. The FF5 is set at the rear edge of the pulse 100, and the passing of the pulse 100 is prevented by the gate 6 while the FF5 is set. Then the FF5 is reset with the output of the gate 4 when all signals given from the reader 2 do not exist any more, and a reading pulse 101 is applied to the circuit 7 from the gate 6. Thus the malfunction due to the double reading is avoided.