WRITING CONTROL APPARATUS

PROBLEM TO BE SOLVED: To surely prevent erroneous writing when prohibiting writing of data to a memory.SOLUTION: In a writing control apparatus, a transmission circuit 4 for transmitting a writing signal is mounted on a writing signal line 3 that extends from a controller 1 to a memory 2. A writing permission/prohibition signal generation section 5 generates an alternating signal as a writing permission signal and generates a non-alternating signal as a writing prohibition signal The signal from the signal generation section 5 is input in a rectification circuit 6, and the rectification circuit 6 generates power source voltage only when the alternating signal is input. In this case, the transmission circuit 4 uses the rectification circuit 6 as an operating power source, transmits the writing signal only when the power source voltage is supplied, and interrupts the transmission of the writing signal when the power source voltage is not supplied.