| 摘要 |
The decoder comprises a microprocessor connected to a receiver of data of teletext and to a text generator for displaying informations on the screen of the television receiver. Further, a card said CPTV-card (card pay-television) is associated to the microprocessor, this card managing the credit necessary for the purchase of emissions, for the memorization of the emissions purchased and for permitting the unscrambling of the emissions purchased by delivering to the microprocessor the input pointer in the sequence which is calculated by the microprocessor by means of the information which has been memorized as well as the information delivered by the decoder. The programs of the forecasted emissions are transmitted by the head station and memorized in the microprocessor of the decoder. Another memory of the microprocessor contains the instructions for the manipulations to be effected for selecting an emission and for purchasing it as well as for recharging a credit in the CPTV-card. A keyboard permits to select and to display on the screen of the television receiver the forecasted emissions as well as the instructions of manipulation which enormously facilitates the dialog between the user and the decoder and contributes to avoid errors of manipulation. The decoder according to the invention operates as a guide for the user, for all operations to be effected. |
