Videotex Services: Network and Terminal Alternatives

Videotex has provisionally become the generic name for interactive systems offering visual information services using a suitably modified or augmented home TV set, telephone and/or data networks, and videotex service centres. This paper starts by briefly introducing the videotex system concept and service possibilities. Examples of existing systems are also given. The main body of the paper considers two areas where new technology has a key role in videotex: in the network of service centres and communications facilities, and in the terminals, both at the information provider´s end and at the consumer´s end.. The trade-offs between multiple-format databases, source coding, terminal complexity and compatibility are examined. The possible solutions to terminal design range from a single, rigid design to an arbitrary combination method. The paper proposes a Layered Capability Structure (LCS) which promotes an evolutionary approach to terminal design.