Processor for use between keyboard telephone set and television set

Claim 1

In a processor for use between an earpiece of a keyboard telephone set serving to interrogate a computer by means of multifrequency code interrogation signals and to receive from said computer digital serial answer words beginning with a start signal and frequency modulating an answer word carrier, and a television set for displaying alpha-numeric characters corresponding to the digital answer words, said telephone set including means for inhibiting the answer frequency modulated carrier from being applied to said earpiece when a key of said keyboard is depressed for multifrequency code interrogation signal transmission, the improvement consisting of: a frequency demodulator for receiving the frequency modulated signals corresponding to values zero and one of the bits of the answer words; a receive register controlled by said start signals for storing the digital answer words; a read only memory of alpha-numeric characters addressed by said digital words; a spatial addressing device addressing by lines and columns the alpha-numeric characters on the screen of the television set; and adjustment means controlled by said frequency demodulator to generate a zero output signal when the input frequency of the frequency modulated carrier has a value corresponding to one of the binary values of the bits of the answer words, so that, when a key of the keyboard of the telephone set is depressed and the answer frequency modulated carrier is then inhibited, the output signal from the demodulator is the same as when a modulation frequency corresponding to said one of the binary values is received; said adjustment means including frequency control means to limit the frequencies of the multi-frequency code range between approximately 697 and 1477Hz and the carriers corresponding to the values 0 and 1 of the bits of the answer words ranging approximately between 1650 and 1850 Hz, said frequency modulator being thereby adjusted at 1650 Hz by said adjustment means, so that, when the demodulator receives a signal at 1650 Hz and when it does not receive any such signal, it produces in both cases a zero output signal.