(or "broadcast teletext") is a television
information retrieval service developed in the United Kingdom
in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules. Subtitle
(or closed captioning
) information is also transmitted in the teletext signal, typically on page 888 or 777.
Around 1970 the BBC
had a brainstorming session in which Stephen Earley decided to start researching ways to send closed captioning
information to the audience. As the so-called Teledata
research continued they became increasingly interested in using the same system for delivering other kinds of information, and not just closed captioning.
Teletext is a means of sending text and diagrams to aproperly equipped television screen by use of one of the "verticalblanking interval" lines that together form the dark band dividingpictures horizontally on the television screen.
Transmitting and displaying subtitles was relatively easy. It requires limited bandwidth
; at a rate of perhaps a few words per second. However, it was found that by combining even a slow data rate with a suitable memory, whole pages of information could be sent and stored in the TV for later recall.
Meanwhile the General Post......