British Post Office VIEWDATA interfacing to a data communication network

The transmission of textual and simple graphical information in serial form via modems connected to the P.O. Public Switched Telephone Network (VIEWDATA) is described. The system is interactive, making use of a keyboard for input, and usually a color television receiver modified to accept and display teletext type information for display. It provides for on line access to a data base of useful information for the general public and business community. The interfacing of VIEWDATA to the N.P.L. data communication network is described together with some consequences of the differences between terminal types and communication conventions.