Ceefax, the original "information superhighway", will cease to exist on Wednesday when the last analogue television signal in the UK is switched off.
Arising out of a brainstorming session at the BBC in the early 1970s, the pioneering teletext service was soft-launched 38 years ago on 23 September 1974, publishing just 30 pages.
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It worked by transmitting the data in the 'vertical blanking interval' between image frames in the broadcast television signal. Viewers entered the three-digit page number they wanted and, when the page was broadcast, it was displayed on the screen.
It was formally launched in 1976 after the BBC and the Independent Broadcasting Authority (IBA), which regulated the regional commercial broadcasters, agreed to a national standard. The Broadcast Teletext Specification was published in September 1976 jointly by the IBA, the BBC and the British Radio Equipment Manufacturers' Association.
The standard offered a 40-column by 24-row grid of text, with some characters reserved for displaying simple block graphics. It was subsequently globalised as the World System Teletext (WST), becoming an international standard under the International Radio Consultative Committee (CCIR) in 1986 as CCIR Teletext System B.
Independent Television's (ITV's) rival, launched just after Ceefax, was called Oracle. No relation to the database company, it stood for "Optional Reception of Announcements of Coded Line Electronics".
At around the same time, the General Post Office (GPO), which ran both the Royal Mail and British Telecom, had been experimenting since the 1960s with a similar Viewdata service using the telephone network. It rushed out Prestel, a dial-up information service offering similar text and graphics display, in response.
Teletext-enabled television sets proliferated in the 1980s as infra-red remote-control fell in price and became a standard feature on television sets. However, it rapidly fell out of favour, first as a result of the internet in the mid-1990s and, subsequently, due to the switch to digital television across the UK.
Prestel, though, failed to take off as it remained too expensive in terms of equipment and telephone charges for the mass market, even after the home computer boom of the early 1980s.
The last "pages from Ceefax", which were displayed overnight on BBC 2, were broadcast on Monday 22 October 2012, while Olympic champion Dame Mary Peters will turn off the last analogue television signal in Northern Ireland at 23.30 BST.
A form of Ceefax, though, has continued to be broadcast under the BBC's "red button" service on digital television, which provides a similar menu of news, sport and other information.
