PURPOSE: To remove distortion from the reproduced waveform of a recorder by connecting a rounding capacitor to a resistance voltage-dividing circuit for recording digital data of a computer.

CONSTITUTION: Digital data 1 and 0 from a computer are supplied to an audio cassette tape recorder by dividing a pulse wave, frequency-modulated into f/2f, by resistance voltage-dividing circuits R1 and R2. In this case, rounding capacitor C is connected in parallel to voltage-dividing circuit R2 so as to round the rises and falls of pulses, thereby obtaining the simple increase and simple decrease waveform of pulses. Consequently, the reproduced waveform of the recorder can be made excellent without distortion.