JPS6231426B

An improved modulator is capable of facilitating recording and reproducing on and from an audio cassette tape digital signals such as programs and numerical data coming from digital signal processing apparatus including an electronic cash register as well as providing safety for the audio cassette tape when in operation. The modulator includes a control circuit for detecting and counting carrier signals and outputting desired information in response to a data transfer instruction and a state detector governed by the control circuit wherein the carrier signals are sent out via data transfer lines when the detector is in a specific state. The control circuit may be implemented with a microprocessor.