Viewdata is a Videotex implementation. It is a type of information retrieval service in which a subscriber can access a remote database via a common carrier channel, request data and receive requested data on a video display over a separate channel. Samuel Fedida, who had the idea for Viewdata in 1968, was credited as inventor of the system which was developed while working for the British Post Office which was the operator of the national telephone system. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels. This is in contrast with teletext.
Viewdata Graphics used in the experimental phone directory of Post Office Telecommunications in 1977. The image is a graphical representation of the Post Office/British Telecom Research laboratories (Adastral Park) in Suffolk, England. Note the "_ to continue" rather than the correct "# to continue", showing a common rendering error.
Detail of a telephone keypad displaying the sextile and Viewdata square
Detail of a telephone keypad substituting an enlarged * and #
Videotex was one of the earliest implementations of an end-user information system. From the late 1970s to early 2010s, it was used to deliver information to a user in computer-like format, typically to be displayed on a television or a dumb terminal.
Videotex example screen showing its graphics capabilities, 1978. As in teletext, predefined, fixed-width graphics characters in multiple colors could be used to create an image.
Minitel was perhaps the most successful videotex service worldwide, using this terminal, c. 1982.
Loewe Multicom E, a late 1980s videotex terminal
An Alex terminal, photographed in 2006
