Editing Videotex (section)

== Initial development and technologies ==

=== United Kingdom ===
The first attempts at a general-purpose videotex service were created in the [[United Kingdom]] in the late 1960s. In about 1970 the [[BBC]] had a brainstorming session in which it was decided to start researching ways to send [[closed captioning]] information to the audience. As the Teledata research continued the BBC became interested in using the system for delivering any sort of information, not just closed captioning.
In 1972, the concept was first made public under the new name [[Ceefax]]. Meanwhile, the [[General Post Office]] (soon to become [[British Telecom]]) had been researching a similar concept since the late 1960s, known as [[Viewdata]].<ref>{{cite web| url=http://aei.pitt.edu/94572/1/videotex.pdf | title=Videotex in Europe | access-date=2023-12-27}}</ref> Unlike Ceefax which was a one-way service carried in the existing TV signal, Viewdata was a two-way system using telephones. Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones. Not to be outdone by the BBC, they also announced their service, under the name [[Prestel]]. ITV soon joined the fray with a Ceefax-clone known as [[ORACLE (teletext)|ORACLE]].

In 1974, all the services agreed on a standard for displaying the information. The display would be a simple 40×24 grid of text, with some "graphics characters" for constructing simple graphics, revised and finalized in 1976.<ref>{{Cite web|url=http://www.doc.ic.ac.uk/%7Eih/teaching/teletext/tt-spec/|title=Broadcast Teletext Specification, September 1976}}</ref> The standard did not define the delivery system, so both Viewdata-like and Teledata-like services could at least share the TV-side hardware, which was expensive at the time. The standard also introduced a new term that covered all such services, [[teletext]]. Ceefax first started operation in 1974 with a limited 30 pages, followed quickly by ORACLE and then Prestel in 1979.

By 1981, Prestel International was available in nine countries, and a number of countries, including Sweden, The Netherlands, Finland and West Germany were developing their own national systems closely based on Prestel. [[General Telephone and Electronics]] (GTE) acquired an exclusive agency for the system for North America.

In the early 1980s, videotex became the base technology for the London Stock Exchange's pricing service called TOPIC. Later versions of TOPIC, notably TOPIC2 and TOPIC3, were developed by Thanos Vassilakis and introduced trading and historic price feeds.<ref>Business Information at Work
By Michael Lowe, 1999, Routledge.</ref><ref>The videotex marketplace: A theory of evolution
Author links open overlay panel. James A.Campbell, Hilary B.Thomas</ref>

=== France ===

Development of a French teletext-like system began in 1973. A very simple 2-way videotex system called Tictac was also demonstrated in the mid-1970s.  As in the UK, this led on to work to develop a common display standard for videotex and teletext, called [[Antiope (teletext)|Antiope]], which was finalised in 1977.  Antiope had similar capabilities to the UK system for displaying alphanumeric text and chunky "mosaic" character-based block graphics.  A difference however was that while in the UK standard [[control codes]] automatically also occupied one character position on screen, Antiope allowed for "non spacing" control codes.  This gave Antiope slightly more flexibility in the use of colours in mosaic block graphics, and in presenting the accents and diacritics of the French language.

Meanwhile, spurred on by the 1978 [[Simon Nora|Nora]]/[[Alain Minc|Minc]] report, the French government was determined to catch up on a perceived falling behind in its computer and communications facilities. In 1980 it began field trials issuing Antiope-based terminals for free to over 250,000 telephone subscribers in [[Ille-et-Vilaine]] region, where the French [[Centre commun d'études de télévision et télécommunications|CCETT]] research centre was based, for use as telephone directories. The trial was a success, and in 1982 [[Minitel]] was rolled out nationwide.

===Canada===

Since 1970, researchers at the [[Communications Research Centre]] (CRC) in [[Ottawa]] had been working on a set of "picture description instructions", which encoded graphics commands as a text stream. Graphics were encoded as a series of instructions (graphics primitives) each represented by a single ASCII character. Graphic coordinates were encoded in multiple 6 bit strings of XY coordinate data, flagged to place them in the printable ASCII range so that they could be transmitted with conventional text transmission techniques. ASCII SI/SO characters were used to differentiate the text from graphic portions of a transmitted "page". In 1975, the CRC gave a contract to [[Norpak]] to develop an interactive graphics terminal that could decode the instructions and display them on a colour display, which was successfully up and running by 1977.

Against the background of the developments in Europe, CRC was able to persuade the Canadian government to develop the system into a fully-fledged service. In August 1978, the Canadian [[Department of Communications (Canada)|Department of Communications]] publicly launched it as [[Telidon]], a "second generation" videotex/teletext service, and committed to a four-year development plan to encourage rollout.  Compared to the European systems, Telidon offered real graphics, as opposed to block-mosaic character graphics.  The downside was that it required much more advanced decoders, typically featuring [[Zilog Z80]] or [[Motorola 6809]] processors.

===Japan===

Research in Japan was shaped by the demands of the large number of [[Kanji]] characters used in Japanese script.  With 1970s technology, the ability to generate so many characters on demand in the end-user's terminal was seen as prohibitive.  Instead, development focussed on methods to send pages to user terminals pre-rendered, using coding strategies similar to [[facsimile machine]]s.  This led to a videotex system called [[Captain (videotex)|Captain]]  ("Character and Pattern Telephone Access Information Network"), created by [[Nippon Telegraph and Telephone|NTT]] in 1978, which went into full trials from 1979 to 1981.  The system also lent itself naturally to photographic images, albeit at only moderate resolution. However, the pages typically took two or three times longer to load, compared to the European systems. [[NHK]] developed an experimental teletext system along similar lines, called CIBS ("Character Information Broadcasting Station"). Based on a 388×200 pixel resolution, it was first announced in 1976, and began trials in late 1978.  (NHK's ultimate production teletext system launched in 1983).