Device for coupling cassette tape recorder and microcomputer

A device for coupling a cassette tape recorder and a microcomputer, comprises a pulse shaper (2), a delay element (10), a flip-flop (12), a commutator (9), a reversible counter (19) and shift register (21). The coupling device also comprises a counter (14) inserted between the output of the delay element (10) and an input (15) of the flip-flop (12), and a timer (23) which controls the operation of all elements of the coupling device. The Timer (23) is built around digital elements. The device functions as an FSK demodulator. The flip-flop is set by pulses from the shaper and reset if timing counter (14) times out before the next pulse. The reversible counter is stepped up or down by each pulse in accordance with the state of the flip-flop. The shift register accommodates the demodulated signal. Timer (23) prevents spurious signals being taken as a synchronizing bit.