 |
The Teletext Museum. |
        |
|
    |
|
|
|
|
|||||||||
|
|||||||||||
EXTRA! EXTRA! READ ALL ABOUT IT!
This article was first published in the Radio
Times, October 1977.
Utopia is on its way. Touch a few buttons ... and your television screen will
throw up, in written form, the latest news, the current sports score, the most recent
weather forecast, exactly when you want it and for as long as it takes you to read it.
Ceefax is the name of the system. So far only a limited number of sets can receive it. But
soon it will be as common as colour.
Bob Smyth explains how it works, and what it can do.
If, like mine, your television set is badly adjusted, you can see a row of flickering dots at the top of the screen. This, I find, is Ceefax. Some years ago BBC engineers found that a normal television picture of 625 lines had 'spare' lines on the edge of the screen which could transmit simple information in letter and number form. Exploring the possibility of transmitting subtitles for the sake of the deaf, they took their discoveries a stage further and came up with a 'television newspaper' suitable for all television users. Commercial television took up the concept; and a standardised system for 'teletext' was agreed with set manufacturers and the Post Office. The result is that each day during normal broadcasting hours 'newspapers' are available on all television channels.
Getting
acquainted with Ceefax ('see facts'), as the BBC system is called, is rather like
childhood visits to the Science Museum - a sense of delight that machines can be so
clever. But playing the buttons in the Ceefax editorial office on the top of Television
Centre seemed a bit frivolous. All around, the Ceefax sub-editors were typing pages onto
monitor screens - VDUs (visual display units) in computer-speak - taking their raw
material from usual newsroom sources: agency teleprinters, the BBC's own General News
Service, television, radio and telephone. Digested into material suitable for Ceefax's
format, It was being fed into a computer which stores the pages and transmits each one
every 25 seconds.
The 25-second cycle is central to an understanding of Ceefax: the system uses two of the spare lines mentioned above, each line capable of transmitting one line of text every 50th of a second. Each page of teletext consists of 24 lines, so a whole page is sent every quarter-second. For the sake of convenience, the size of the Ceefax magazine was fixed at 100 pages, meaning that an entire magazine could be transmitted every 25 seconds. The user dials - or, rather, taps in on his push-button control - the number of the page he wants, and when it appears on screen it is held there until another page is ordered. Whichever page the user wants to see will come up on his screen in anything from 0 to 25 seconds.
BBC1 and BBC2 offer separate magazines. The first, in the words of Colin McIntyre, Editor of Ceefax, Is a 'daily' magazine, while BBC2's is 'more of a weekly'. As with a conventional newspaper, Ceefax's main interest Is news, but it has sections on weather, entertainment and consumer matters, finance and sports.
The advantage of Ceefax over news services provided by other media is it is instantaneous. For budgets and Major events, like general elections, Ceefax's news editor can shuffle all his pages to offer coverage which will give the viewer all the bad news instantly.
Additional capabilities make Ceefax even more useful and attractive. The system can transmit maps and diagrams and uses up to six colours, as well as white. Text can also be superimposed on normal pictures (which was what the engineers were interested in in the first place). This means you can watch, say, Match of the Day without missing newsflashes about the latest hi-jack or the health of some giraffe. You can also order particular pages in advance, so that as soon as the result of the third race at Llngfield is announced it appears automatically.
Finally there is a device whereby the 100-page capacity of the magazine could in theory be expanded fourfold. On, say the Police News page, a note promises 'More in a moment' and another complete page appears shortly after with up to two more following it. These extra pages are the result of an instruction to the computer to transmit a different version of say, page 142, after two cycles of the magazine - namely, every 50 seconds. In practice Ceefax uses this potential to give its BBC1 magazine some 140 pages instead of its apparent 100.
The difficulty Ceefax faces at the moment is that to receive teletext you need to add a decoder to your existing set, at a cost of over £300, or to buy a new set, at around £700. But costs will fall as the market expands; and some 50,000 sets will be receiving Ceefax by 1978. In future years Ceefax will offer regionalised news and an added reason for investing in a teletext-compatible set will be the advent of a Post Office system providing thousands of pages of on-screen information, sent via an ordinary telephone line.
Ceefax, as Colin McIntyre describes it, is the beginning of a video revolution which will have a major effect on our lives. The user will not only be able to summon thousands of pages of text through a phone-TV set link but will be able to talk back to the computers sending the information, whether for the purpose of booking summer holidays or ordering the weekly groceries. The Post Office is to launch its initial Viewdata public trials next year; but one advantage that Ceefax will keep over the Post Office system is that Ceefax is free whereas Viewdata will cost the price of a call. Timechecks, for instance appear on every Ceefax page. Greatest of all, Ceefax's attraction is that it is here already, two years ahead of other countries who have begun to experiment with teletext based on the BBC system.
Teletext Timeline | An Evening with Ceefax
|
|||
|
The Teletext Museum
is a collaboration with |
|
|
|
|
|
|||
|
