High security videotext and videogame system

A receiving station decoder for a system for the secure transmission and pay per view viewing of scrambled broadcast signals of television, videotext and videogame programming, the decoder adapted for use with a home game computer, the decoder comprising

• an internal fixed memory containing a fixed station-unique internal code;
• a removable electrically alterable memory module containing at least one station-unique external code and a portion onto which billing information may be entered;
• means for generating a descrambling signal complementary to the scrambling signal upon the input of a proper numerical sequence;
• a remote memory unit connected to the decoder and accessible therefrom and adapted for connection to and to be also accessed by the home game computer;
• and
• a microprocessor programmed (1) to read the internal code from the internal memory, and the external code from the memory module, (2) to derive a broadcast code from the broadcast signal, (3) to combine the internal and external codes to generate a numerical code for descrambling the broadcast signal, (4) if the broadcast code indicates that the broadcast signal is videotext or videogame programming, to logically combine the numerical code to the videotext and videogame programming received and to load the result directly into the remote memory unit, (5) if the broadcast code indicates that the broadcast signal is television programming, to direct the numerical code to the means for generating the descrambling signal, and (6) to write information about television, videotext or videogame broadcast signals received, as derived from the broadcast code, into the memory module so that use of the decoder can be billed on a usage basis both for television programming and for videotext and videogame programming.