Control program signal demodulating device

A control program signal demodulating device suitable for an interactive operation of a player for playing a rotary recording medium and an external control device which is coupled to said player so that said external control device controls an operation of said player depending on an external instruction and depending on a control program which is loaded into said external control device, said control program including input and output commands and internal processing commands of said external control device, said rotary recording medium comprising track turns which are recorded with at least a control program signal, a video signal and an address signal, said player comprising a pickup reproducing element for scanning said track turns so as to reproduce recorded signals from said rotary recording medium and a controller for controlling a reproducing track position of said pickup reproducing element and for producing a status data signal which indicates an operating state of said player, said address signal indicating a track turn which is being scanned by said pickup reproducing element, said control program signal demodulating device comprising:

• a control program demodulator for demodulating said control program signal which is reproduced from said rotary recording medium, the demodulated control program signal indicating said control program;
• memory means for at least temporarily storing the demodulated output signal of said control program demodulator, said status data signal and said address signal and for producing the stored signals;
• selecting means for selecting one of the signals which are produced by said memory means;
• interface means for transmitting the signal which is selected by said selecting means to said external control device, and for receiving at least one control command which is produced by said external control device depending on said external instruction and said control program;
• and
• a command analyser for decoding said at least one control command received by said interface means, and for supplying a signal to said controller so as to control the operation of said player and supplying a transmission request signal to said selecting means so as to determine which one of the signals produced by said memory means is selected by said selecting means,
• said control program demodulator comprising wave-shaping means for wave-shaping the reproduced control program signal, first and second flip-flops coupled in series so that an output signal of said wave-shaping means is applied to an input terminal of said first flip-flop and an output signal of said first flip-flop is applied to an input terminal of said second flip-flop, said first and second flip-flops respectively having a clock terminal applied with the horizontal synchronizing signal of the reproduced video signal, and comparing means for comparing the output signal of said first flip-flop and an output signal of said second flip-flop and for producing an output signal which has a level depending on whether or not the output signals of said first and second flip-flops are equal to each other.