Viewdata

Viewdata Graphics used in the experimental phone directory of the General Post Office in 1977

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. The access, request and reception are usually via common carrier broadcast channels. This is in contrast with teletext.

Technology

Originally Viewdata was accessed with a special purpose terminal (or emulation software) and a modem running at CCITT V.23 speed (1200 bit/s down, 75 bit/s up). Today it is normally accessed over TCP/IP using Viewdata client software on a personal computer running Microsoft Windows.

Travel industry

Viewdata is still in use today in the United Kingdom, mainly by the travel industry. Travel agents use it to look up the price and availability of package holidays and flights. Once they find what the customer is looking for they can place a booking.

The travel industry is trying to move away from Viewdata to a Web based standard. There are a number of factors holding up a move to the Web. Travel consultants have been trained to use Viewdata, they would need training to book holidays on the Internet and the tour operators can't agree on a Web based standard.

Bulletin board systems

A number of Viewdata Bulletin Board Systems existed in the 1980s, predominantly in the UK due to the proliferation of the BBC Microcomputer, and a short-lived Viewdata Revival appeared in the late 1990s fuelled by the retro-computing vogue. Some Viewdata boards still exist, with accessibility in the form of Java Telnet clients. Examples:

• CCl4,
• Haven.

See also

• Federal Standard 1037C
• Prestel

External links

• Definition at The Institute for Telecommunication Sciences