View source for Prestel

{{Short description|British videotex service}}
{{for2|the publisher|Prestel Publishing|people with the surname|Prestel (surname)}}
{{Use British English|date=January 2023}}
{{Use dmy dates|date=November 2024}}

{{Infobox online service
|name=Prestel
|title=Prestel
|logo=Prestelc.png
|logo_size=250px
|logo_alt=
|logo caption=Prestel logo designed by<br/>Mervyn Kurlansky of [[Pentagram (design firm)|Pentagram]]<ref name=AlexReid>
{{
cite web
|url=https://static1.squarespace.com/static/5c65dd81af46834afd07e40a/t/614e475f5de10e1b7e24f272/1632520053512/lives+retold+reid+alexander+24.9.21.pdf
|access-date=24 October 2024
|title=Alexander Reid : Autobiographical life story
|at=See section "Prestel", pp. 120{{ndash}}129
|date=24 September 2021
|first=Alexander
|last=Reid
|website=www.livesretold.co.uk
}} Alexander "Alex" Reid was the first Director of Prestel at [[BT_Group#Post Office Telecommunications|Post Office Telecommunications]] / [[BT Group|British Telecom]], holding the post during the service's initial development and for the first few years after its commercial launch.</ref>{{rp|124}}
|developer=[[BT_Group#Post Office Telecommunications|Post Office Telecommunications]]
|key_people=[[Samuel Fedida]]
|generation=
|type=General-purpose<br/>public [[videotex]] service
|launched={{Start date and age|1979}} 
|discontinued={{End date and age|1994}}
|version=
|version release date=
|preview version=
|preview version release date=
|updated=
|platform=[[GEC_4000_series|GEC 4000]] [[minicomputer]]s in a [[star network]] configuration with [[Packet Switch Stream|packet-switched]] connections
|operating system=[[OS4000]] [[operating system]] supporting [[GEC_4000_series#Babbage|BABBAGE]] [[high-level assembler|high-level assembly]] language
|pricing=Subscription (quarterly) and usage (time spent on system, some pages, some messaging service actions)
|status=Discontinued
|members={{circa|lk=no}} 95,500 terminals attached at peak
|availability=
|website=
}}

'''Prestel''' was the [[Brand#Brand names and trademark|brand name]] of a [[videotex]] service launched in the UK in 1979 by [[BT Group#Post Office Telecommunications|Post Office Telecommunications]], a division of the British [[Post Office Limited#History|Post Office]].{{refn|group=lower-alpha|name=Name|According to Alex Reid, the first Director of Prestel: "The question of what our commercial viewdata system should be called was given 
careful thought ... To build a commercial brand we had to choose a new name. I undertook this process personally, compiling a long list of simple words [and] then subjected a short list to professional 
checking for availability and protection worldwide ... [t]he winner in this exercise was Prestel. Pre had connotations of press, presentation, press button, prestige and premium. Tel had the telecomms connotation."<ref name=AlexReid />{{rp|123{{ndash}}124}}}} It had around 95,500 attached terminals at its peak,<ref name=SchofieldJan89>
{{
cite news
|newspaper=[[The Guardian]]
|date=19 January 1989
|title=Path of Gold
|first=Jack
|last=Schofield
|author-link=Jack Schofield (journalist)
|page=27
|url=https://www.proquest.com/docview/186963681 
|id={{ProQuest|186963681}}
|quote=With ... 95,460 terminals (not users) ... .
}}</ref> and was a forerunner of the internet-based online services developed in the late 20th and early 21st centuries.<ref name=Davenport2023>
{{cite journal 
|last=Davenport 
|first=Lucinda D. 
|date=2023 
|title=The Viability of Viewdata as a Mass Medium: A Case Study of Prestel, the Prototype for Computerized Information Systems, the Internet |journal=TMG Journal for Media History 
|volume=26 
|issue=2 
|pages=1{{ndash}}29 
|doi=10.18146/tmg.845 
|issn=1387-649X 
|doi-access=free}}</ref> Prestel was discontinued in 1994 and its [[asset]]s sold by [[BT Group|British Telecom]] to a company [[consortium]].<ref name=PrestelSaleInd>
{{
cite news
|newspaper=[[The Independent]]
|title=Prestel rings the changes as BT hangs up
|first=Andrew
|last=Bibby
|date=2 April 1994
|url=https://www.independent.co.uk/news/business/prestel-rings-the-changes-as-bt-hangs-up-1367604.html
|access-date=16 November 2024
}}</ref><ref name=Rutter />{{rp|146}} 

A subscriber to Prestel used an adapted TV set with a keypad or keyboard, a dedicated terminal, or a microcomputer to interact with a central [[database]] via an ordinary [[Telephone line|phoneline]]. Prestel offered hundreds of thousands of pages of general and specialised information, ranging from consumer advice to financial data, as well as services such as home banking, online shopping, travel booking, [[telesoftware]], and messaging.

In September 1982, to mark Information Technology Year,{{refn|group=lower-alpha|IT82 was a £3.75m UK government initiative to raise awareness about information technology and promote its take-up.<ref name=IT82>
{{
cite web
|url=https://www.computinghistory.org.uk/det/49343/Information-Technology-Year-1982/
|access-date=20 November 2024
|title=Information Technology Year 1982
|website=[[Centre for Computing History]]
}}</ref>}} the [[Royal Mail]] issued two [[commemorative stamp]]s, one of which featured a Prestel TV set and keyboard.<ref name=CommemStamp-1982>
{{
cite web
|url=https://www.collectgbstamps.co.uk/explore/issues/?issue=9
|access-date=20 November 2024
|title=Information Technology
|website=Collect GB Stamps
}}</ref>
In April 1984, [[BT Group|British Telecom]] won a [[The King's Awards for Enterprise|Queen's Award for Technological Achievement]] for the development of Prestel.<ref name=QueenAward>
{{London Gazette
|issue=49713
|date=21 April 1984
|page=2
|supp=y
|title=The Queen's Award for Technological Achievement 1984
|quote = ''Her Majesty the Queen has been graciously pleased to confer Her Award for Technological Achievement in 1984 upon ... :'' The Videotex Section of BT Research Department and the Prestel Executive of British Telecommunications, Martlesham Heath, Ipswich and London, E.C.4. ''Nature of product or development:'' 'Prestel' viewdata system.
}}</ref>

==History==
===Invention and development===
In 1970, [[Samuel Fedida]], a [[Engineering research|research engineer]] who had worked at [[English Electric]] and a US [[consultant|consultancy]] company, joined the [[BT Group#Post Office Telecommunications|Post Office]] as head of the Computer Applications Research Division. Within a year, he had completed the initial design of a [[viewdata]] system (the generic term in use at the time) for the general public: it would comprise information stored on a central computer accessed over the public [[telephone network|phone network]] using modified televisions as terminals. By early 1973, the Post Office had decided to develop an experimental system, and was working with the [[BBC]], the [[Independent Broadcasting Authority]], and [[standards organization|standards organisations]] to develop compatible standards for [[teletext]] and viewdata. During 1974, it decided to commercialise the viewdata concept.<ref name=Rutter />{{rp|107{{ndash}}109}}

===Pilot trial===
The first public demonstration of [[viewdata]] took place in London in 1975 during Eurocomp, the European Computing Conference on Communications Networks,<ref name=EurocompTimes>
{{
cite newspaper The Times
|title=Why the Post Office is so excited by its plans for a TV screen information service
|first=Kenneth
|last=Owen
|department=Business news
|date=26 September 1975
|page=23
|issue=59511
|column=4
|url=https://www.thetimes.com/tto/archive/article/1975-09-26/23/4.html
|quote=Earlier this week the proposed new service was publicly demonstrated for the first time at ... Eurocomp ... at Heathrow. Yesterday the philosophy behind Viewdata was described at the conference by Samuel Fedida [...].
}}</ref> where Fedida presented a paper on the technology and the potential appeal, as the Post Office saw it, of a public interactive information service.<ref name=FedidaEurocomp>
{{
cite book
|url=https://archive.org/details/communicationsne0000euro/
|title=Communications Networks: Papers presented at the European Computing Conference on Communications Networks (Eurocomp){{snd}}London, September 1975
|chapter-url=https://archive.org/details/communicationsne0000euro/page/260/mode/2up
|chapter=Viewdata: an interactive information service for the general public
|pages=261{{ndash}}282
|first=Samuel
|last=Fedida
|publisher=Online Conferences Ltd
|location=[[Uxbridge]]
|date=1975
|isbn=978-0-903-79605-7
|oclc=2006258
|via=Internet Archive
|url-access=registration
|access-date=28 October 2024
|quote=The concept of Viewdata, a computer-based information medium and service, suitable for non-computer users, is explained by reference to the 'total cost-effectiveness' of computer-based information systems. The means of implementing such a system includes the design of a low-cost, yet of pleasing appearance, rugged and reliable terminal connected to the telephone system, together with its associated keypads, a distributed but interconnected computer system giving access to internal and external databases, a 'natural' protocol for information retrieval requiring no training whatsoever for its effective use and a software structure designed to maximise throughput and hence minimise costs.
|quote-page=261
}}
</ref>

Further demonstrations followed, and based on the favourable reactions of TV manufacturers and potential providers of information and services, the Post Office decided to run a pilot trial.<ref name=Rutter />{{rp|110}} It also agreed with potential information providers (IPs) that it would not select IPs or exert editorial control over what they put on the system.<ref name=Reid-1981>
{{
cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|first=Alex
|last=Reid
|chapter=Prestel philosophy and practice
|pages=13{{ndash}}28
|chapter-url=https://archive.org/details/viewdatainaction0000unse/page/12/mode/2up
|quote-page=16
|quote=[W]e plumped firmly for the 'common carrier' approach. We rent space in our Prestel computers to anyone who can pay the storage charges. The information providers may choose whether to charge the users to look at their information, and if so, how much; and information providers may put up on their pages whatever information they wish, subject only to the law.
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
|access-date=5 October 2024
}}</ref>

The two-year pilot service began in January 1976.<ref name=Rutter />{{rp|111}} By mid-1977, IPs included the [[Which?|Consumers' Association]], the British Farm Produce Council, [[British Rail]], [[London Transport Executive (GLC)|London Transport]], the [[Open University]], the [[London Stock Exchange]], the [[Institute for Scientific Information]], and [[Girobank|National Giro]].<ref name=PilotTrialTimes>
{{
cite newspaper The Times
|title=Dial-a-fact television becoming reality
|department=Telecommunications
|date=26 May 1977
|page=17
|issue=60013
|column=1
|url=https://www.thetimes.com/tto/archive/page/1977-05-26/17.html
}}</ref>{{rp|cols 3{{ndash}}4}} Interviewed by ''[[The Times]]'', Fedida was quoted as saying that the [[BT Group#Post Office Telecommunications|Post Office]] saw viewdata playing several roles: as a "centralised information source", an "intelligent interface" to specialised scientific and technical data, a "communication machine" for passing messages, a personal information store, a new information distribution medium, a "channel for education in the home", and as providing an "advanced calculator service".<ref name=PilotTrialTimes />{{rp|cols 2{{ndash}}3}}

===Test service===
After some delay,<ref name=Rutter />{{rp|113}}<ref name=Large-Oct1978>
{{
cite news
|newspaper=[[The Guardian]]
|date=3 October 1978
|title=Prestel's passing problems
|first=Peter
|last=Large
|page=19
|url=https://www.proquest.com/docview/186049881 
|id={{ProQuest|186049881}}
}}</ref> the [[BT Group#Post Office Telecommunications|Post Office]] launched a test service of Prestel, as it was now called,{{refn|group=lower-alpha|name=Name}} in October 1978. At the end of December, there were 95,500 information pages, growing at a rate of 3,500 per week,  and just over 300 users, increasing by 30{{ndash}}50 per week.<ref name=Williams1979 />{{rp|56}}

===Commercial launch===
{{see also|#Information providers}}
In March 1979, the Post Office opened a limited "London Residential Service" for subscribers in the capital.<ref name=StokesViewdataBook />{{rp|22{{ndash}}23}} The full commercial service launched in September 1979;<ref name=Rutter />{{rp|115}} the director of Prestel stated that there were over 130,000 pages in the database and 1363 "sets" connected to the system at the start of that month.<ref name=Reid-Sept79Gdn>
{{
cite news
|newspaper=[[The Guardian|Guardian]]
|title=Prestel develops the world's biggest system
|date=13 September 1984
|pages=22{{ndash}}23
|first=Alex
|last=Reid
|url=https://www.proquest.com/docview/186086404/
|url-access=subscription
}}</ref>{{rp|23 col 4}}

By February 1980, there were 131 IPs and 116 sub-IPs. The Post Office categorised the IPs as follows: national and local newspaper groups; magazine and other publishing groups; central government departments, and other agencies (such as the [[VisitBritain|British Tourist Authority]] and the [[British Library]]); [[Nationalization|nationalised]] industries (including [[British Airways]], [[Sealink]], and [[British Rail]]), and companies in other fields of business, such as banks and travel agencies; new companies set up to exploit the viewdata medium, and those expanding from an existing base of online services, such as [[Reuters]]; associations; software companies; and miscellaneous.<ref name=Williams-IPs />{{rp|100{{ndash}}101}}

Particularly popular were the travel-oriented nationalised industries; new companies, such as Fintel;<ref name=Fintel-formed>
{{
cite newspaper The Times
|title=FT and Extel form joint venture
|department=Financial news and market reports
|date=12 January 1978
|page=21
|issue=60208
|column=2
|url=https://www.thetimes.com/tto/archive/article/1978-01-12/21/5.html
}}</ref> and the [[Which?|Consumers' Association]].<ref name=Williams-IPs>
{{
cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|first=Ederyn 
|last=Williams
|author-link=Ederyn Williams
|chapter=Who's who on the Prestel database
|pages=99{{ndash}}106
|chapter-url=https://archive.org/details/viewdatainaction0000unse/page/99/mode/2up?view=theater
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
|access-date=29 October 2024
}}</ref>{{rp|102}} Overall, popular topics included games, quizzes, jokes, and horoscopes; the [[London Stock Exchange|Stock Market]], company information, and business news; travel and holiday information; national news, sports, and "What's On" locally; cars; and consumer advice.<ref name=Williams-IPs />{{rp|103}} This was reflected in advertisements for Prestel.<ref name=TimesAd1980>
{{
cite newspaper The Times
|title=Learn More From Your Telly. Read It
|date=24 March 1980
|issue=60583
|at=p. 3: full-page advertisement showing 21 Prestel pages.
|url=https://www.thetimes.com/tto/archive/page/1980-03-24/3.html
|quote=
}}</ref>

Writing in the winter 1980/81 issue of ''British Telecom Journal'', Prestel's public relations manager stated there were over 7,500 sets attached to the system, 170,000 frames in use, and more than 400 IPs and sub-IPs.<ref name=BTJwinter1980-81>
{{
cite journal
|journal=British Telecom Journal
|issn=0260-1532
|title=Market review for Prestel
|first=Richard
|last=Hope-Smith
|volume=1
|issue=4
|pages=8{{ndash}}9
|date=1980–1981
|oclc=8560549
<!--|url=http://www.samhallas.co.uk/repository/journals/BT_Journal/BTJ%20Vol%201%20No%204%20Winter%201980-1.pdf-->
}}</ref>{{rp|9}} By the end of 1981, according to Butler Cox, a [[management consulting|management consultancy]],<ref name=ButlerCox1982>
{{
cite web
|url=https://archivesit.org.uk/wp-content/uploads/2021/09/BCF-RRBT-03-1982-Iss1.pdf
|access-date=1 November 2024
|title=Developments in Videotex
|date=March 1982
|author=Butler Cox
|publisher=Butler Cox & Partners
|location=London
|series=Butler Cox Report Series #27
|website=Archives of IT
|oclc=
}}</ref>{{rp|9}} Prestel had 2,000 residential and 11,000 business users, with 14,000 "terminals"{{sic|nolink=y}} in use. The service was within local call reach of 62% of phone subscribers in Britain. IPs numbered 153, with 593 sub-IPs. Users accessed 190,000 frames per day, and the average time on the system, for each user per day, was 9 minutes. There were 193,000 frames available, including 2,000 response frames. {{section link|#Response_frames}}

====Prestel Gateway====
March 1982 saw the launch of the Prestel Gateway service. This enabled users to connect, via the Prestel network, to external computers operated by IPs or other companies.<ref name=GatewayAslibProc>
{{
cite journal
|journal=ASLIB Proceedings
|first=Chris
|last=Horne
|title=Gateway{{snd}}an enhancement of Prestel
|volume=34
|issue=5
|date=1982
|pages=266{{ndash}}270
|doi=10.1108/eb050847
|issn=0001-253X
}}</ref> Travel agents, for example, used Gateway to connect to [[Tour operator|tour operators']] systems and make reservations.<ref name=Rutter />{{rp|153}}

====User charges====
At the launch of the commercial service in September 1979, and in addition to phone charges, users were charged 3p per minute online to Prestel from 8&nbsp;am to 6&nbsp;pm Monday to Friday, and 3p for three minutes at other times. Installing a [[British telephone socket#Sockets|phone jack-socket]] cost £13, with a quarterly rental of 50p. Business users paid an additional standing charge (i.e., a flat charge regardless of usage) of £12 per quarter.<ref name=BTstaffGuideCirca1979>
{{
cite document
|title=Prestel: A brief guide [for British Telecom staff] to British Telecom [sic] Viewdata Service
|author=Prestel Marketing Duty
|date=c. 1979
|publisher=British Telecom
|location=Bedford
|pages=6{{ndash}}7
|type=pamphlet
}}</ref>

By October 1982, the online usage charge had risen to 5p per minute (8&nbsp;am to 6&nbsp;pm Monday to Friday and also 8&nbsp;am to 1&nbsp;pm on Saturdays, free at other times), the business standing charge to £15 per quarter, residential users now paid £5 per quarter, and jack installation cost "from £15", with a 15p quarterly rental fee.<ref name=IPcharges />{{rp|2}}

===Growth===
From September 1986,<ref name=TelematicsTransition>
{{
cite book
|title=Telematics in Transition: The Development of New Interactive Services in the United Kingdom
|first1=Graham
|last1=Thomas
|first2=Ian
|last2=Miles
|date=1989
|publisher=[[Longman]]
|location=[[Harlow]]
|isbn=978-0-5820-5595-7
|oclc=22706270
}}</ref>{{rp|27}} under page *656#, Prestel's publicity department  published a "Factframe" showing, at the end of each month, the average number of terminals attached and the respective percentages in businesses and in homes; the number of frames available and the number of frame accesses per week; and the number of messages sent per week.<ref name=Factframe>An example from 1987: 
{{
cite document
|type=videotex frame 65659a
|title=Factframe to end of Oct 1987
|date=October 1987
|publisher=Prestel Publicity Department
<!--|url=https://archive.org/details/prestel-factframe-example-->
}}
</ref> Actual subscriber figures were not published; Thomas et al. (1992) suggest these were "significantly less" than the number of terminals, as "businesses were assumed to 'attach' more than one terminal", and note that British Telecom stopped publishing figures at the end of 1988.<ref name=SettingStage>
{{
cite book
|first1=Graham
|last1=Thomas
|first2=Thierry
|last2=Vedel
|first3=Volker
|last3=Schneider
|author-link3=:de:Volker Schneider (Politikwissenschaftler)
|date=1992
|editor-first1=Harry
|editor-last1=Bouwman
|editor-link1=Harry Bouwman
|editor-first2=Mads
|editor-last2=Christoffersen
|editor-link2=dk:Mads Christoffersen
|title=Relaunching Videotex
|publisher=Springer-Science+Business Media
|location=[[Dordrecht]]
|pages=15{{ndash}}30
|chapter=Chapter 2: The United Kingdom, France and Germany: Setting the Stage
|url=https://books.google.com/books?id=H5iqCAAAQBAJ&pg=PA18
|doi=10.1007/978-94-011-2520-8_3
|isbn=978-94-011-2520-8
|oclc=7330970413
}}</ref>{{rp|18}}

In September 1982, ''[[The Times]]'' reported there were 18,000 users, of whom 3,000 were residential.<ref name=Times-stats-Sept82>
{{
cite newspaper The Times
|title=Prestel plans another offensive
|first=Bill
|last=Johnstone
|department=Computers and Technology
|date=6 September 1982
|page=13
|issue=61330
|column=2
|url=https://www.thetimes.com/tto/archive/article/1982-09-06/13/7.html
}}</ref> Noting that British Telecom had originally forecast 50,000 users at this point, the report went on to outline a new approach to attracting them, quoting senior managers from British Telecom and the head of a [[joint venture]]. The plans involved the introduction of a home banking service; the marketing of a Prestel adaptor for computer terminals to the business and higher education sectors; and the launch of [[Micronet 800]], a service for microcomputer users. 

Six months later, in February 1983, the same newspaper recorded 22,400 users, of whom 15% were residential, writing that the future of Prestel "could be in doubt by 1985 if it is not approaching profitability."<ref name=Times-stats-Feb83>
{{
cite newspaper The Times
|title=Prestel races to attract business
|first=Bill
|last=Johnstone
|department=Business News
|date=3 February 1983
|page=16
|issue=61447
|column=2
|url=https://www.thetimes.com/tto/archive/article/1983-02-03/16/4.html
}}</ref>

In mid-1984, the UK [[Department of Trade and Industry (United_Kingdom)|Department of Trade and Industry]] issued a booklet stating that the availability of travel information, the launch of [[Micronet 800]], and the provision nationwide of the messaging service, Mailbox, had contributed to a rise to 45,000 attached terminals by June of that year. 61% were in businesses, and 39% in homes. In that month, on average, the Prestel database contained 320,000 frames that were accessed 14.6 million times. 17 Prestel Gateways to external computers were in operation.<ref name=DTI-1984>
{{
cite book
|title=Viewdata in Retail and Distribution
|author=Department of Trade & Industry
|author-link=Department of Trade and Industry (United Kingdom)
|date=1984
|at="Key facts and statistics", p. 8 (unnumbered)
|publisher=IT Division, Department of Trade & Industry
|location=London
|oclc=17676964
|id=[[British Library]] shelfmark GPB-4720
}}</ref> For July, the Butler Cox [[management consulting|consultancy]] recorded 47,000 users (60% business, 40% residential), and a total of 1,200 IPs and sub-IPs.<ref name=ButlerCox1985 />{{rp|26, Fig. 1.15}}

After another year, in mid-1985, ''[[The Times]]'' stated there were 53,000 "terminals, adapted televisions, microcomputers or specially designed units" attached to Prestel, with residential users now accounting for 45% of the total. In the reporter's view, this represented "a change of fortune for [a service] deemed commercially dubious by many commentators."<ref name=Times-stats-03June85>
{{
cite newspaper The Times
|title=Households attracted to Prestel
|first=Bill
|last=Johnstone
|department=Home News
|date=3 June 1985
|page=3
|issue=62154
|column=2
|url=https://www.thetimes.com/tto/archive/article/1983-02-03/16/4.html
}}</ref> The figure of 65,000 was reached at the beginning of 1986{{snd}}about a third were [[Micronet 800]] subscribers. Prestel had reportedly traded at a profit from the previous October onwards.<ref name=Times-stats-14Jan86>
{{
cite newspaper The Times
|title=Prestel moves into the black
|first=Matthew
|last=May
|department=Computer Horizons
|date=14 January 1986
|page=28
|issue=62344
|column=4
|quote=Last October Prestel ... announced it had begun to make a profit in its day-to-day operations for the first time in its six-year existence. Only two years ago it was being suggested ... it should be shut down as an expensive mistake.
}}</ref> Commenting in September 1986 on what it referred to as "only 70,000 users ... growing at a rate of ... a few hundred customers a week", ''[[The Times]]'' declared that Prestel "had failed to live up to expectations", comparing it unfavourably to the French [[Minitel]] videotex service and to British Telecom's own [[Telecom Gold]] electronic mail service.<ref name=Times-stats13Sept86>
{{
cite newspaper The Times
|title=BT aims to link Prestel with Telecom Gold
|first=Jonathan
|last=Miller
|department=Business and Finance
|date=13 September 1986
|page=22
|issue=62562
|column=3
}}</ref>

Writing in ''[[The Guardian]]'' just before Christmas 1988, [[Jack Schofield (journalist)|Jack Schofield]] reported that Prestel "had become reclusive" about user numbers, with the Factframe, "[a]fter prompting, ... finally updated this summer ... claim[ing] 90,000 users", while the figure of "only 75,000" was being quoted by the British Telecom manager responsible for the service.<ref name=SchofieldDec88>
{{
cite news
|newspaper=[[The Guardian]]
|date=22 December 1988
|title=Numbers down
|first=Jack
|last=Schofield
|author-link=Jack Schofield (journalist)
|at=p. 27, col 8
|url=https://www.proquest.com/docview/186886612 
|id={{ProQuest|186886612}}
}}</ref> In January 1989, drawing on what turned out to be the final Factframe, published at the end of 1988, Schofield wrote that "After ten years, [Prestel] has yet to achieve the number of users it expected to get in its first year", quoting a figure of 95,460 terminals attached.<ref name=SchofieldJan89 /> This was the highest figure claimed during the lifetime of Prestel.<ref name=SettingStage />{{rp|18}}

===Decline===
In October 1991, British Telecom closed [[Micronet 800]], stating, in a letter to customers, that "With over 10,000 members, Micronet is easily the largest online service in the UK specialising in microcomputing. However, it is still not large enough to enable us to maintain a cost-effective service and provide the extra facilities requested by our customers."<ref name=MicronetClosure1991>
{{
cite web
|url=https://www.viewdata.org.uk/download.php?cat=15_Prestel&file=micronetrip.pdf
|title=Micronet to close from 31st October 1991
|date=27 September 1991
|first1=Sue
|last1=Gilbody
|type=letter
|publisher=[[Tymnet#BT Tymnet, BT_North America, BTNA|BT Tymnet]]
|archive-url=https://web.archive.org/web/20120506132636/http://www.viewdata.org.uk/download.php?cat=15_Prestel&file=micronetrip.pdf
|archive-date=6 May 2012
}}</ref> Membership had decreased from a peak of around 20,000.<ref name=Rutter />{{rp|145}} ''[[The Guardian]]'' attributed this to the introduction by British Telecom of an off-peak Prestel time-charge in mid-1988, discouraging the use of Micronet's popular "[[Micronet 800#Services provided|Chatline]]" service.<ref name=BrownMicronet1991>
{{
cite news
|newspaper=[[The Guardian]]
|date=31 October 1991
|title=Reaching the end of the line
|first=Mike
|last=Brown
|at=p. 33, col 8
|url=https://www.proquest.com/docview/187285975 
|id={{ProQuest|187285975}}
}}</ref> ''[[The Times]]'' agreed, and also pointed to a steep rise in subscription charges, opining that "BT's failure to provide even this committed group with an economic ... service means that Prestel is destined ... for businesses."<ref name=MayMicronet1991>
{{
cite newspaper The Times
|title=Hey Prestel! A disappearing act
|first=Matthew
|last=May
|department=Science and Technology
|date=3 October 1991
|page=30
|issue=64141
|column=1
}}</ref> The closure in April 1991 of Homelink, the [[online banking|home banking]] service launched in 1983 by the [[Nottingham Building Society]],<ref name=HomelinkClosureArticle>
{{
cite journal
|journal=Journal of Retail Banking
|title=Why home banking bombed in Britain
|first=Philip A.
|last=Dover
|volume=15
|issue=4
|date=Winter 1993
|pages=30{{ndash}}38
|id={{Gale|A15141702}}
|issn=0195-2064
}}</ref>{{rp|1}} also contributed to shrinking the number of Prestel subscribers.<ref name=Rutter />{{rp|146}}

During 1991, Prestel was closed to residential users.<ref name=Rutter />{{rp|146}} Towards the end of 1993, it was reported that British Telecom was planning to close Prestel altogether: according to the company, of the around 35,000 subscribers at that point, only some 2,500 used the service regularly.<ref name=ClosureLaurance>
{{
cite news
|newspaper=[[The Guardian]]
|date=13 November 1993
|title=British Telecom poised to close its loss-making Prestel service
|first=Ben
|last=Laurance
|at=p. 38, col 5
|url=https://www.proquest.com/docview/187571026 
|id={{ProQuest|187571026}}
}}</ref>

===Closure===
British Telecom closed Prestel in early 1994, selling it to a [[consortium]]. It was rebranded as "New Prestel", focusing on the provision of financial data to businesses.<ref name=PrestelSaleInd /> In mid-1996, New Prestel transferred to the [[World Wide Web|Web]], becoming the [[Internet service provider]] (ISP)  "Prestel On-line"<ref name=PrestelOn-line>
{{
cite news
|newspaper=[[The Independent]]
|title=Steps one, two and three{{snd}}hey Prestel!
|first=Alan
|last=Stewart
|date=28 July 1996
|url=https://www.independent.co.uk/life-style/steps-one-two-and-three-hey-prestel-1331077.html
|access-date=14 December 2024
}}</ref><ref name="PrestelOn-lineArchive">
{{
cite web
|url=http://www.prestel.co.uk/online.htm
|archive-url=https://web.archive.org/web/19970208234324/http://www.prestel.co.uk/online.htm
|archive-date=8 February 1997
|title=Prestel HotZone : Follow the Markets with Prestel On-Line!
|website=Prestel On-line Services
|access-date=14 December 2024
}}</ref>

In 1999, the financial data component of Prestel On-line was bought by the company Financial Express to become "Financial Express Prestel".<ref name=FinExpressPrestel>
{{
cite web
|url=https://www.campaignlive.co.uk/article/financial-express-buys-prestel-online/120097
|title=Financial Express buys Prestel Online
|date=20 October 1999
|website=[[Campaign (magazine)|Campaign UK]]
|access-date=14 December 2024
|quote=Online content supplier Financial Express has bought real-time pricing provider Prestel Online from its management team. Following the purchase, FE will change its name to Financial Express Prestel and specialise in supplying data on equities, unit trusts, investment funds and life and pensions funds.
}}</ref> The service component merged with the ISP [[Demon Internet]],<ref name=DemonPrestel>
{{
cite news
|newspaper=M2 PressWire
|title=Prestel: Demon and Prestel alliance creates new Internet force
|date=13 January 1999
|publisher=Normans Media
|id={{Gale|A53563938}}
|quote=Demon Internet and Prestel On-line today announced the alliance of the two Scottish Telecom companies which will create one of the most competitive offerings in the UK Internet Service Provider (ISP) market.
}}</ref> which ran a "Prestel Internet Service". This closed in 2002.<ref name=Rutter />{{rp|146 ft 158}}

===Analyses===
Writing in early 1979 about the [[#Test service|test service]] that had launched in October 1978, a [[BT_Group#Post_Office_Telecommunications|Post Office]] executive concluded that:{{blockquote|text= "The strengths of viewdata include its visual attractiveness, its ease of use, low cost and its wide range of applications. Its weaknesses include its small information window, unsophisticated search methods, its limited storage capacity and its lack of computer power for users. How rapidly viewdata will become established, and the exact role it will fulfil, is as yet a matter of speculation."<ref name=Williams1979>
{{
cite journal 
|first=Ederyn
|last=Williams
|author-link=Ederyn Williams 
|title=Strengths and Weaknesses of Prestel 
|journal=Computer Communications
|date=April 1979 
|volume=2 
|issue=2 
|pages=56{{ndash}}59
|doi=10.1016/0140-3664(79)90121-X
}}</ref>}}

In the aftermath of Prestel's [[#Information and services|pivot away, in the early 1980s, from a focus on the general public]] to targeting the business community, the [[profession|professions]], and microcomputing enthusiasts,<ref name=ButlerCox1985 />{{rp|25}} [[A. Michael Noll|Noll]] (1985) studied the possible reasons for Prestel's lack of take-up by households. He concluded that the following factors might have been significant: a shortage, at the beginning of the commercial service, of affordable Prestel-adapted TV sets and, later, adaptors; relatively high frame-access and time-based online charges; the large size of the [[#Database|database]], and the difficulty of searching it; and the variation in how information providers (IPs) arranged and presented their Prestel pages.<ref name=Noll-1985>
{{
cite journal
|journal=Information & Management
|title=Videotex: anatomy of a failure
|volume=9
|issue=2
|pages=99{{ndash}}109
|date=September 1985
|first=A. Michael
|last=Noll
|author-link=A. Michael Noll
|url=https://www.polyarchives.hosting.nyu.edu/files/original/2c4421f4c8f7ba4b61518599f648ebdc.pdf
|access-date=17 February 2025
|archive-url=https://web.archive.org/web/20250216211636/https://www.polyarchives.hosting.nyu.edu/files/original/2c4421f4c8f7ba4b61518599f648ebdc.pdf
|archive-date=16 February 2025
|doi=10.1016/0378-7206(85)90031-X
|issn=0378-7206
|oclc=38995112
}}</ref>{{rp|99{{ndash}}100}}

[[A. Michael Noll|Noll]]  contrasted the "relative failure" of Prestel with the "success" of [[teletext]], noting that receiving the latter was free and its database much smaller.<ref name=Noll-1985 />{{rp|101{{ndash}}102}} Overall, he questioned "the [...] hypothesis that the information needs of consumers can be satisfied by a large, centralized, computerized database of general-interest information."<ref name=Noll-1985 />{{rp|105}}

After consulting a group of experts in the [[videotex]] domain, the [[information scientist]]s [[Varun Grover (information scientist)|Grover]] & Sabherwal drew conclusions (1989) that largely concurred with Noll's. In addition, they judged that government [[subsidy|subsidies]] were required to boost public interest and mass take-up.<ref name=Grover-1989>
{{
cite journal
|journal=Journal of Systems Management
|title=Poor Performance of Videotex Systems
|volume=40
|issue=6
|pages=31{{ndash}}37
|date=June 1989
|first1=Varun
|last1=Grover
|author1-link=Varun Grover (information scientist)
|first2=Rajiv
|last2=Sabherwal
|url=https://www.proquest.com/docview/199811361
|id={{ProQuest|199811361}}
|issn=0022-4839
|oclc=928083662
}}</ref> This latter view was also held by [[Digital sublime#Origins of the digital sublime|Mosco]], a [[political economy|political economist]], who wrote in 1982: "[T]he British government appears to be prepared to let Prestel sink or swim on its own commercial ability {{sic|nolink=y}} ... It is too early to offer a complete assessment of Prestel. However, the direction of development is clear: the need for immediate commercial success means cutting back on earlier mass marketing efforts and an emphasis on specific business uses."<ref name=Mosco-1982>
{{
cite book
|title=Pushbutton Fantasies : critical perspectives on videotex and information technology
|first=Vincent
|last=Mosco
|date=1982
|publisher=[[Ablex Publishing|Ablex]]
|location=[[Norwood, New Jersey|Norwood]]
|isbn=978-0-893-91125-6
|oclc=8626459
}}</ref>{{rp|77}}

In a paper published shortly after Prestel had been discontinued in 1994, Case, an information scientist, examined the motivations behind the development of this and other videotex services from a [[sociology|sociological ]] perspective. In his view, "[E]xplanations of videotex  require consideration of higher-level phenomena [such] as policy, [[ideology]], belief, and vision".<ref name=Case-1994>
{{
cite journal
|journal=Journal of the American Society for Information Science
|title=The Social Shaping of Videotex: How Information Services for the Public Have Evolved.
|volume=45
|issue=7
|pages=483{{ndash}}497
|date=August 1994
|first=Donald O.
|last=Case
|issn=0002-8231
|oclc=802881625
|url=https://www.proquest.com/docview/216901916
|id={{ProQuest|216901916}}
}}</ref>{{rp|495}} He identified the envisioning of videotex as a facilitator of mass participation in an emerging [[Information society#Sociological uses|information society]]<ref name=Crawford-1983>
{{
cite journal
|journal=Bulletin of the Medical Library Association
|title=The Origin and Development of a Concept: The Information Society
|first=Susan  
|last=Crawford
|date=1983
|volume=71
|issue=4
|pages=380{{ndash}}385
|pmid=6652297
|pmc=227258
}}</ref>{{snd}}a belief held and promoted by many politicians, [[futurist|futurists]], sociologists, and business leaders in the 1960s and 1970s{{snd}}as a crucial spur to the development of the technology, sustained investment, and the roll-out of services.<ref name=Case-1994 />{{rp|485{{ndash}}487}} This vision was animated, according to [[Information and communications technology|communications technology]] researchers Harmeet & Sandvig's summary (2006) of scholarly views, by the "converging agendas of myriad players ... all seeking to increase revenues in otherwise saturated markets": phone companies (increased network traffic), set and terminal manufacturers (more sales), newspapers and news agencies (additional outlets for content), and business sectors such as banks and the travel trade (looking to reduce [[transaction cost]]s).<ref name=HarmeetSandvig-2006>
{{
cite conference 
|first1=Harmeet
|last1=Sawhney 
|first2=Christian
|last2=Sandvig
|title=Approaching Yet Another New Communication Technology 
|conference=[[International Communication Association]] (ICA): 56th Annual Conference
|pages=1{{ndash}}28 
|date=20 June 2006 
|location=[[Dresden]]
|id={{EBSCOhost|dbcode=ufh|27203868}}
}} {{subscription required}}</ref>{{rp|13{{ndash}}14}}
 
Regarding Prestel, Case summarised the problems it faced (as described by a former chief executive)<ref name=Hooper-1984>
{{
cite web
|title=Prestel, Escher, Bach: changes within changes
|publisher=[[Program on Information Resources Policy]], [[Harvard University]]
|type=incidental paper
|first=Richard
|last=Hooper
|author-link=Richard Hooper (civil servant)
|date=January 1984
|id=I-84-1
|url=http://www.pirp.harvard.edu/pubs_pdf/hooper/hooper-i84-1.pdf
|archive-url=https://web.archive.org/web/20080607040301/http://www.pirp.harvard.edu/pubs_pdf/hooper/hooper-i84-1.pdf
|archive-date=7 June 2008
|access-date=20 February 2025
}} Reprinted in
{{
cite book
|title=Issues in New Information Technology
|editor-first=Benjamin M.
|editor-last=Compaine
|pages=15{{ndash}}24
|date=1988
|publisher=[[Ablex Publishing|Ablex]]
|location=[[Norwood, New Jersey|Norwood]]
|isbn=978-0-893-91468-4
|oclc=243361472
}}</ref> as the lack of a trigger service,{{refn|group=lower-alpha|A key service or feature that would have attracted subscribers and kept them engaged.}} low-quality information, complicated charges, competing services, and uncoordinated marketing by IPs, [[BT Group|British Telecom]], and terminal and adaptor providers.<ref name=Case-1994 />{{rp|492}} Insufficient market research into "what sorts of information people actually use, and what delivery modes are appropriate for them" was identified by [[Public policy#Academic discipline|public policy]] researchers Thomas & Miles (1989) as a further reason why Prestel failed to live up to expectations.<ref name=TelematicsTransition />{{rp|26}}

Poor, a communications researcher, suggested (2006) that the failure of Prestel to achieve significant [[Mass market#Definition|mass-market]] take-up was linked to its "highly centralized and closed" nature.<ref name=Poor-2006>
{{
cite conference 
|first=Nathaniel
|last=Poor 
|title=When They Built the Internet and No One Came: The Failure of Videotex and the Triumph of Open Systems  
|conference=[[International Communication Association]] (ICA): 54th Annual Conference
|pages=1{{ndash}}30
|date=May 2006
|location=[[New Orleans]]
|id={{EBSCOhost|dbcode=ufh|45284295}}
}} {{subscription required}}</ref>{{rp|1}} He cited the control over content exercised by IPs and the system operator, [[BT Group|British Telecom]],<ref name=Poor-2006 />{{rp|9}} coupled with a lack of [[wikt:connectivity#noun|connectivity]] to both non-videotex online services and other videotex services based on different [[Technical standard|technical standards]].<ref name=Poor-2006 />{{rp|23{{ndash}}24}} On standards, Poor (2004) believed that "A universal videotex standard would have been like the common gauge for railroad, or common standards for the telegraph or the telephone. Disparate systems could connect, and enjoy [[Network effect|network externalities]] due to scale."<ref name=Poor-2004>
{{cite thesis 
|first=Nathaniel 
|last=Poor 
|date=2004
|title=Democratic technologies: Openness, decentralization, and the success of information systems
|chapter=Chapter 5: Videotex: control and communication in the decade before the Internet
|pages=150{{ndash}}184
|degree=PhD
|publisher=[[University of Michigan]]
|id={{ProQuest|305181173}}
|url=https://www.proquest.com/docview/305181173
|isbn=978-0-496-85092-1
|oclc=148537515
}}</ref>{{rp|181 ft 24}}

==Database==
===Pages and frames===
====Numbering====
Information on Prestel was held in a database of "pages". Each page corresponded to a screenful of information, and had a unique number up to nine digits long.{{refn|group=lower-alpha|I.e, page numbers could run from 0 to 999999999.}}

A page could have up to 26 sub-pages, with each sub-page labelled with a letter from "a" to "z". A sub-page was called a "frame": the page itself was frame "a". Neither pages nor frames could scroll.<ref name=E-Bookstall>
{{cite book
|first=Rex
|last=Winsbury
|author-link=Rex Winsbury
|title=The Electronic Bookstall : Push-button publishing on videotex: a critical study of Prestel in Britain
|date=1979
|publisher=International Institute of Communications
|location=London
|isbn=978-0-904-77610-2
|oclc=5507588
|url=https://archive.org/details/electronicbookst0000wins
|url-access=registration
}}</ref>{{rp|20{{ndash}}21}}<ref name=CustomerBrochure1982>
{{
cite document
|author=British Telecom
|author-link=BT Group
|date=September 1982
|type=Customer brochure
|title= Prestel
|location= London
|publisher=Prestel Public Relations
|id=Prestel P526 9/82
}}</ref>{{rp|2}}<ref name=BBCmicroPrestel1984>
{{
cite web
|url=https://archive.org/details/acorn-prestel-system-user-guide-bbc-micro/
|access-date=7 October 2024
|title=Prestel System User Guide{{snd}}BBC Micro
|date=March 1984
|author=Acorn Computers
|author-link=Acorn Computers
|via=Internet Archive
}}</ref>{{rp|2}}

Each IP rented a three-digit number as its master page. For example, the [[Met Office|Meteorological Office]]'s was 209,<ref name=Handbook1987 />{{rp|6}} and the numbers identifying all its pages began with these digits{{snd}} such as for 20971, the page for "Aviation forecasts".<ref name=StartUpDir1987 />{{rp|1}} 

Single- and double-digit pages were reserved by Prestel for system information purposes, such as page 1, which showed the main index. Pages starting with 9 were for account and other system management functions: page 92, for example, showed details of a Prestel user's bill.<ref name=CustomerBrochure1982 />{{rp|10}}

====Types====
Most frames were set up to provide information. Other types were for [[#Messaging|messaging]], or provided a [[#Prestel Gateway|gateway]] to services on other computers. A "follow-on" type caused the next frame in sequence to be automatically displayed as soon as the current frame had filled the screen.

By embedding [[control character|cursor-control characters]] in the page, simple animations could be produced by rewriting parts of the screen already displayed. These were known as "dynamic frames".<ref name=Dynamic-1>
{{
cite magazine
|magazine=[[Amstrad Computer User]]
|title=Prestel{{snd}}living by numbers
|page=36
|issue=6
|date=May 1985
|url=https://archive.org/details/AmstradComputerUser06-0585/page/n35/mode/1up
|quote=One of the latest features of Prestel is the dynamic page. Usually a page only shows a static image, either text or a diagram[.] By using a dynamic frame it is possible to animate the graphics. This works by sending commands to the user’s system to move the cursor and then print another bit.
|access-date=19 March 2025
|via=[[Internet Archive]]
}}</ref>{{refn|group=lower-alpha|Dynamic frames could not be created online: their preparation required specialist software and then uploading via the "bulk update" facility. No timing options were available beyond those imposed by the transmission speed, which was usually 1200 [[baud]].}} Combined with the follow-on attribute, this provided a way to continue animations that could not fit within the number of characters available in one frame alone.{{citation needed|date=March 2025}}

This follow-on frame attribute was also used for [[telesoftware]], enabling computer programs, such as those for the [[BBC Micro]], to be downloaded from Prestel.{{refn|group=lower-alpha|The first few frames acted as headers. For example, a program would be described on frames 70067a and b, while frame c gave the number of subsequent frames containing the program, and a [[checksum]].The telesoftware program itself started in frame d. To verify a successful download, software compared the checksum with a value calculated from the result of downloading all the frames required. If the check failed, the program had to be downloaded again.<ref name=BBCmicroPrestel1984 />{{rp|30}}}}<ref name=BBCmicroPrestel1984 />{{rp|30{{ndash}}31}}

====Layout, design, and writing for Prestel====
Each frame had 24 lines of 40 characters each, and as in the format used by the [[Ceefax]] and [[ORACLE (teletext)|ORACLE]] [[teletext]] services, could contain a maximum of 960 characters. The bottom line was reserved for system messages, leaving 920 characters for the Information Provider (IP). The top line, showing the name or logo of the IP, the page number, and the price,<ref name=CustomerBrochure1982 />{{rp|7}} occupied at least 43 characters, depending on the design of the logo. This left 22 lines and a maximum 877 characters available for the IP to present information to the user.<ref name=BUS1981>
{{
cite web
|url=https://archive.org/details/prestel-bulk-update-technical-specification-november-1981-page_numbers_added/
|access-date=7 October 2024
|title=Prestel Bulk Update Technical Specification
|date=November 1981
|id=Ref.&nbsp;14&nbsp;9&nbsp;81p
|author=British Telecom
|author-link=BT Group
|via=Internet Archive
}}</ref>{{rp|12}} 

When preparing and editing a page, an IP could use upper- and lower-case letters, digits, punctuation marks, a few arithmetic symbols, and a set of "[[Digital image#Mosaic|mosaic characters]]" for composing rudimentary graphics.<ref name=Handbook1987 />{{rp|19}}{{refn|group=lower-alpha|The character set conformed with a variant of the [[ISO/IEC 646]] and [[CCITT]] standards; it was formalised in the 1981 CEPT videotex standard as the [[CEPT Recommendation T/CD_06-01|CEPT3]] profile.<ref>
{{
cite web 
|title=Terminal Equipment (TE): videotex presentation layer protocol, videotex presentation layer data syntax
|id=ETS 300 072
|date=November 1990 |url=http://www.etsi.org/deliver/etsi_i_ets/300001_300099/300072/01_60/ets_300072e01p.pdf
|publisher=[[ETSI]]
|location=[[Sophia Antipolis]]
|access-date=9 October 2024
}}</ref>}} The appearance of a character could be changed using a [[control character|display-attribute code]].<ref name=PrestelTermSpec1982 />{{rp|37}} These modified the appearance of subsequent characters on the same row of the screen, and themselves occupied one character position, which was displayed as a space.<ref name=PrestelTheTechnology>
{{
cite document
|author=British Telecom
|author-link=BT Group
|date=August 1980
|type=Technical brief
|title= Prestel. The Technology.
|location=London
|publisher=Prestel Public Relations
|id=P507/8/80
}}</ref>{{rp|15}}

In early 1978, at the end of the [[#Pilot trial|pilot trial]], [[BT_Group#Post Office Telecommunications|Post Office Telecommunications]] commissioned a study of the content and function of Prestel and how these aspects related to the [[graphic design]] of Prestel pages.<ref name=M&A-stage1>
{{
cite web
|url=https://ia801907.us.archive.org/21/items/prestel-mills-allen-1979/Prestel_MillsAllen_1979_text.pdf
|access-date=15 April 2025
|via=[[Internet Archive]]
|title=Prestel, the editorial opportunity: A report of the first year of editorial research
|date=March 1979
|publisher=Mills & Allen Communications
|location=London
|type=research report
}}</ref>{{rp|1{{ndash}}2}} Several graphics designers were consulted (including the designer of Prestel's logo and its index and system pages),<ref name=Kurlansky-1982>
{{
cite journal
|journal=American Fabrics and Fashions
|title=Pentagram: Prestel
|first=Mervyn
|last=Kurlansky
|issue=127
|pages=66{{ndash}}67
|date=1982
|via=[[Herberger Institute for Design and the Arts#Units|ASU FIDM]]
|id=Accession no. SC2011.1168.60
|issn=0748-3228
|quote=In terms of typography, we were faced with limitations that put us back 2,000 years.
|quote-page=66
}}</ref> along with professional writers, journalists, media specialists, and database managers.

On graphic design, the main conclusions reached were to encourage IPs to use only a few colours on each page; to take into account the variety of TV sets and other terminals in use (colour or monochrome, different screen sizes, a range of [[serif]] or [[sans-serif]] [[typeface]]s); and to accommodate users with poor sight or [[Color blindness|colour blindness]].<ref name=M&A-stage1 />{{rp|18{{ndash}}19}} Building on the study's results and the outcomes of other research, Reynolds (1979) made recommendations for presenting text, tables, indexes and graphics in Prestel-type videotex systems and in [[teletext]].<ref name=Reynolds-1979>
{{
cite journal
|journal=Information Design Journal
|title=Teletext and viewdata{{snd}}a new challenge for the designer
|first=Linda
|last=Reynolds
|volume=1
|issue=1
|date=1979
|pages=2{{ndash}}14
|doi=10.1075/idj.1.1.02rey
|issn= 0142-5471
|quote=[B]ecause the medium is less than perfect for reading, it is all the more important that the presentation in terms of layout and the use of colour should be optimal.
|quote-page=13
}}</ref>

On writing for Prestel, the main finding of the study was to never undertake the composition and editing of content without considering the physical and technical limitations of the Prestel page and the overall [[#Structures|structure]] of the information of which it formed a part.<ref name=M&A-stage1 />{{rp|12}} On style, the study's report highlighted the views of the writer and academic [[Raymond Williams]]:{{refn|group=lower-alpha|Concluding remarks at the study's ''Writing for Prestel'' seminar, London, 15 November 1978.}} "The English sentence is a very flexible animal, and we all know what happened to it with the invention of printing. We shouldn't feel confined by it in Prestel."<ref name=M&A-stage1 />{{rp|2.8}}

Surveying how Prestel's content had developed a year or so after its [[#Commercial launch|commercial launch]], [[Rex Winsbury]], a media journalist and editorial director of Fintel,{{refn|group=lower-alpha|Fintel was a [[joint venture]] between the ''[[Financial Times]]'' and [[Extel]].<ref name=Fintel-formed />}} a major IP, wrote:<ref name=WinsburyInAction>
{{
cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|first=Rex
|last=Winsbury
|author-link=Rex Winsbury
|chapter=Electronic editing: database and page design
|pages=145{{ndash}}154
|chapter-url=https://archive.org/details/viewdatainaction0000unse/page/145/mode/1up
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
|access-date=26 February 2025
}}</ref>{{rp|151}}{{blockquote|text=[E]diting demands that something useful be said on each page without fuss or flannel in a very short space. Viewdata does not like long sentences or qualifications. Nor must you cram too many words on to the screen; otherwise it looks a mess. Each page has to have a single message, and a clear one at that. Two short paragraphs ... or a few columns of figures to a page, are the most you will find ... It comes down to what newspapermen {{sic|nolink=y}} call "tight subbing".}}

===Links===
A page could be directly linked to up to ten other pages by specifying, during editing, the number of the page whose content would be displayed when a user pressed a digit from 0 to 9 on their keypad or keyboard.<ref name=E-Bookstall />{{rp|20}} Double-digit links{{snd}}such as "56"{{snd}}were achieved by linking the first digit to an intermediate, stepping-stone frame on the IP's database: this, in turn, connected the second digit to the target page.<ref name=White-1978>
{{
cite journal
|journal=[[Journal of Information Science#Publication history|Information Scientist]]
|title=Viewdata{{snd}}a Review
|first=Martin S.
|last=White
|volume=12
|issue=4
|pages=144{{ndash}}153
|date=December 1978
|issn=0020-0263
|url=https://archive.org/details/viewdata-a-review-white-m-s-1978
|access-date=27 January 2025
|via=Internet Archive
}}</ref>{{rp|149}}

The content of pages ranged between two poles: at one, a menu listing the topics available and the number to key to reach them, with no, or minimal, further information{{snd}}referred to as an "index page"; and at the other, a screenful of information with few, if any, links to other pages{{snd}}an "information page". According to [[Rex Winsbury]], as experience with the [[viewdata]] medium grew, IPs "gave information on all or most pages, simply varying the amount according to the number of routings [links] that have to be given as well."<ref name=E-Bookstall />{{rp|22}}

===Structures===
[[File:Prestel videotex service database - "inverted tree" structure.png|thumb|alt=A diagram in the form of an upside-down stylised tree|upright=1.5|Original Prestel "inverted tree" database structure: each page could be linked to up to ten other pages]]When the public Prestel service began in 1979, a user connecting to the system was presented with the main index page. As they made and keyed successive menu choices, they moved down a subject hierarchy, from the general to the specific, to finish with the information page they sought.<ref name=Orna-1986>
{{
cite journal
|journal=Information Design Journal
|first=Elizabeth
|last=Orna
|title=Information management by design: improving information retrieval on Prestel
|date=1986
|volume=5
|issue=1
|pages=61{{ndash}}68
|doi=10.1075/idj.5.1.04orn
|issn=1569-979X
}}</ref>{{rp|61}} The Post Office, academics, and the media referred to this [[hierarchical database model|hierarchical database]] arrangement as a [[tree structure]] or "inverted tree".<ref name=Williams-1978>
{{
cite web
|title=Database Organisation and Information Retrieval{{snd}} a discussion paper
|first=Ederyn
|last=Williams
|author-link=Ederyn Williams
|date=18 July 1978
|website=www.whatdotheyknow.com
|id=BL: SGV 78/10. PO: PO-IP CP-26
|url=https://www.whatdotheyknow.com/request/prestel_site_1980s_4/response/73455/attach/4/Structuring%20BL%20Information.pdf
|access-date=14 October 2024
|quote=The database was initially organised on the 'tree principle', in which pages were organised into a single massive tree, and page access was presumed to be primarily through a series of single digit choices.
|quote-page=1
}} Note: this Post Office document was published by [[WhatDoTheyKnow]] as part of the outcome of a [[Freedom of information in the United Kingdom|Freedom of Information]] request [https://www.whatdotheyknow.com/request/prestel_site_1980s_4/ made to The British Library in February 2010.]</ref>{{rp|1}}<ref name=Storey-1982>
{{
cite journal
|journal=Journal of Information Science
|title=The future of videotex systems{{snd}}a personal view
|first=I. N. J.
|last=Storey
|date=1982
|volume=4
|issue=2{{ndash}}3
|pages=111{{ndash}}115
|doi=10.1177/016555158200400207
|issn=0165-5515
}}</ref>{{rp|112}}<ref name=SchofieldGdn-1>
{{
cite news
|newspaper=[[The Guardian|Guardian]]
|title=How the Post Office failed to deliver
|date=13 September 1984
|page=17
|first=Jack
|last=Schofield
|author-link=Jack Schofield (journalist)
|url=https://www.proquest.com/docview/186463562
|id={{ProQuest|186463562}}
|url-access=subscription
|quote=The tree structure means a large proportion of the frames are simply 'routeing' frames. They contain no useful information, but simply direct you on the long route to where that information is held.
}} [column 2]</ref>{{rp|col. 2}}

[[File:Prestel videotex service database - backlinks.png|thumb|alt=A diagram in the form of an upside-down stylised tree showing links back to the top|upright=1.5|Links back to the main index were the first refinement made]]
Though simple in theory, in practice this structure could lead a user to a dead end: they might find that how a subject was described in a menu did not match what they saw on the final destination page, or formed only part of what they were looking for, or provided information without the means to look up related material. Going back through the sequence of menu choices (using the *# command) to try another series of links was limited to three steps in all.<ref name=Orna-1986 />{{rp|62{{ndash}}63}} 

[[File:Prestel videotex service database - cartwheel structure.png|thumb|alt=A diagram in the form of a stylised cartwheel showing links from the hub to pages on the rim that are themselves sequentially connected|With the "cartwheel", a user could browse pages in sequence, such as monthly statistics, or access each page directly]]As Prestel developed, IPs accommodated the particularities of  the different types of information and services they provided, and the expectations of their users, through the extensive use of backlinks and crosslinks between their pages.<ref name=Yeates1988 />{{rp|9}}
This resulted in a variety of database structures<ref name=Williams-IPs />{{rp|104{{ndash}}105}} that acquired labels such as cartwheels, ring-of-rings, Chinese lanterns and lobster-pots to help visualise how pages were connected.<ref name=E-Bookstall />{{rp|24}} IPs were exhorted to keep things simple from the user's point of view:<ref name=Williams-IPs />{{rp|105}}{{blockquote|text=The more varied the requirements of users, the more complex the routeing structures become{{snd}}not that the user will perceive them as complex. Indeed, he should see such a structure as very simple to use, as helpful routeing choices are offered to him at each stage, whatever his needs or interests.}}

===Navigation and search===
{{multiple image
 | total_width = 250
 | footer = Pocket guide to Prestel for medical practitioners, {{circa|lk=no}} 1984. Their welcome page was 1629.<ref name=MedProgRep>
{{
cite journal
|journal=Medical Informatics
|date=1982
|volume=7
|issue=2
|pages=141–142
|author=<!--no author stated-->
|title=Short progress report: Present and potential uses of Prestel by the medical profession
|doi=10.3109/14639238209010707
}}
</ref> ''Laminated card, 6.9 x 11 cm''
 | image1 = Prestel-for-Medics pocket-guide front.png
 | alt1 = Front of guide
 | caption1 = ''front''
 | image2 = Prestel-for-Medics pocket-guide back.png
 | alt2 = Back of guide
 | caption2 = ''back''
}}There were three basic navigation commands:<ref name=Handbook1987 />{{rp|20}}
* *number# took the user directly to the first frame of the page number specified: for example, *5052# displayed the contents of 5052a onscreen; 
* <nowiki>#</nowiki> moved the user successively forward through the frames: 5052b, 5052c, and so on; 
* *# returned the user to the previous page in strict sequence, and could be repeated three times.

Keyword access was introduced in 1987, with *keyword# taking the user directly to the subject (or subject index) specified.<ref name=Yeates1988>
{{
cite journal
|journal=The Indexer
|title=Prestel indexing from the user's point of view
|first=Robin
|last=Yeates
|date=April 1988
|volume=16
|issue=1
|pages=7{{ndash}}10
|doi=10.3828/indexer.1988.16.1.3
|issn=1756-0632
}}</ref>{{rp|8}}<ref name=Handbook1987 />{{rp|20}}

A topic index, updated daily, was published on page 199, and an IP index on page 198. A printed A{{nbnd}}Z ''Start-Up Directory'' of the topics available on Prestel, with the appropriate page number to key, was sent to new users. From 1987, the topic names could also be used as keywords.<ref name=StartUpDir1987>
{{
cite document
|author=[[BT Group|British Telecom]] 
|date= 1 September 1987
|title=Prestel Start-Up Directory 
|location=London 
|publisher=Prestel
|type=handbook 
}}</ref> [[Micronet 800]], an IP, visualised the relationships between its pages in a [[Tube map|London Tube-style ]] schematic map as part of a guide for users.<ref name=MicronetTubeMap>
{{
cite web
|url=https://archive.org/details/your-guide-to-micronet-1986/mode/2up
|title=Your Guide to Micronet
|page=4
|date=1986
|publisher=Telemap
|location=London
|via=Internet Archive
}}</ref>
 
From 1983 to mid-1987, ''The Prestel Directory'', a [[Calendar year#Quarters|quarterly]] magazine, was distributed free to all Prestel users and also available on subscription: it contained a user guide and subject index, a list of  IPs and sub-IPs, feature articles, and videotex product news.{{refn|group=lower-alpha|{{ISSN|0266-0288}}. {{OCLC|1230877457}}.}} This was superseded by ''Connexions'', sent to users every two months till May 1988.<ref name=ConnexionsMay88>
{{
cite web
|url=https://www.computinghistory.org.uk/det/24135/Connexions-April-May-1988/
|access-date=16 October 2024
|title=Connexions [cover]
|date=April–May 1988
|publisher=[[BT Group|British Telecom]]
|website=[[Centre for Computing History]]
|id=CH24135
|issn=0951-3140
|oclc=220057513
}}</ref> A directory was also incorporated into the quarterly ''Prestel Business Directory'' published by the ''[[Financial Times]]'' from 1979.<ref name=BizDir1981>
{{
cite web
|url=https://www.computinghistory.org.uk/det/56750/Prestel-Business-Directory-(Oct-1981)/
|access-date=16 October 2024
|title=Prestel Business Directory [cover]
|date=October 1981
|publisher=Financial Times Business Publishing
|issn=0142-5102
|oclc=225634964
|website=[[Centre for Computing History]]
|id=CH56750
}}</ref>

From January 1986, Prestel published ''Focus'' magazine on page 123 "to show you the most useful, entertaining and topical pages from the thousands available."<ref name=PrestelOfflineJan86>
{{
cite document
|first=Yvonne
|last=Hicks
|date=January 1986
|type=customer newsletter
|title=Prestel Offline
|location=London
|publisher=Prestel Public Relations
|at=p. 1, col 1, "Focus on Prestel "
}}</ref> It spotlighted news, sport, weather, and entertainment information on a daily basis, and included weekly features.<ref name=PrestelDir1986edn2>
{{
cite magazine
|magazine=The Prestel Directory
|title=A day in the life of Focus
|first=Sanchie
|last=Heesom
|page=66
|date=1986
|issue=2
|publisher=Directel
|location=Birmingham
|issn=0266-0288
}}</ref>

==Information providers==
There were two types of information provider (IP): main IPs, and sub-IPs.
===Charges===
====Page rental====
A main IP rented pages from the [[Post Office Limited|Post Office]] (initially) or [[BT Group|British Telecom]] (later), and controlled a three-digit master-page in the database. In 1982, this cost an annual £5,500 for a basic package,<ref name=IPcharges>
{{
cite web
|url=https://archive.org/details/prestel-ip-and-user-prices-oct-1982
|title=Information Provider (IP) Charges and User Charges
|author=[[BT Group|British Telecom]]
|date=October 1982
|access-date=8 October 2024
|via=Internet Archive
}}</ref>{{rp|1}} equivalent to around £29,000 in 2021.<ref name=MeasuringWorth>
{{
cite web
|url=https://www.measuringworth.com/calculators/ukcompare/
|title=Five Ways to Compute the Relative Value of a UK Pound Amount, 1270 to Present
|publisher=[[MeasuringWorth|The MeasuringWorth Foundation]]
|access-date=9 October 2024
}}</ref>

The basic package included 100 frames; the ability to enter and amend information, retrieve response frames, and store 10 completed response frames; staff training in editing (a two-day seminar), and a copy of the IP editing manual; and, if required, bulk update facilities and an annual print-out of frames in use. Additional frames were available, in batches of 500, for £500 a year (over £2,600 in 2021),<ref name=MeasuringWorth /> while using "Closed User Groups" (CUGs){{refn|group=lower-alpha|name=CUG|A Closed User Group, or CUG, was a group of Prestel users, set up by an Information Provider, with access to confidential information.<ref name=Handbook1987 />{{rp|18}}}} and the sub-IP facility each cost £250 annually<ref name=IPcharges />{{rp|1}} (over £1,300 in 2021).<ref name=MeasuringWorth /> 

Sub-IPs{{snd}}those with smaller requirements or budget{{snd}}rented pages from a main IP.<ref name=Broadhead>
{{
cite journal
|journal=[[The Post Office Electrical Engineers' Journal|Post Office Electrical Engineers' Journal]]
|title=Prestel: The First Year of Public Service
|first=W. R.
|last=Broadhead
|volume=74
|issue=2
|pages=129{{ndash}}133
|date=July 1981
|url=https://archive.org/details/poeej198107/page/n63/mode/1up
|access-date=7 October 2024
|via=Internet Archive
}}</ref>{{rp|130}} A main IP could rent out pages at the [[market rate]]. Such IPs were known as "umbrella" IPs. Sub-IPs paid a per-minute charge for editing online: in 1982, this was 8p per minute from Monday to Friday between 8 am and 6 pm, and 8p per four-minute block at all other times<ref name=IPcharges />{{rp|1}} Sub-IPs had a four-digit (or more) master-page within a main IP's area. Generally speaking, they could only edit existing pages, and were not able to create or delete them.

====Gateway====
The cost to an IP of connecting an external computer to the Prestel system varied according to the number of simultaneous users required, the distance between Prestel and the IP's computer, and whether the connection was made using a private line or via the [[Packet Switch Stream|PSS]] [[packet switching|packet-switched]] network. There were also time and data-volume charges.<ref name=GatewayCharges>
{{
cite document
|title=Prestel Travel Tariff Guide
|date=November 1985
|type=brochure
|publisher=Prestel Travel
|location=London
}}</ref>{{rp|3}} Other factors to be taken into account included the traffic pattern (i.e., the expected volume and frequency of [[wikt:data flow|data flows]]), the [[Response time (technology)#Computing|response time]] required (as perceived by a user), the size of the database to be accessed, and the changeability of the information stored.<ref name=GatewayWelcome>
{{
cite web
|url=https://archive.org/details/Welcome-to-Prestel-Gateway
|title=Welcome to Gateway
|date=1982
|type=brochure 
|publisher=Prestel Public Relations
|location=London
|via=Internet Archive
|access-date=13 January 2025
}}</ref>{{rp|12{{ndash}}13}}

In 1985, British Telecom estimated that for an IP using a typical [[minicomputer]] (such as the [[PDP-11]]) located 100 km from London and handling up to 10 users simultaneously at peak times, the one-off software set-up cost would be at least £16,000, communication costs would range from £4,280 to £5,550 a year (depending on the type of connection), and Prestel usage would cost £8,600 a year.<ref name=GatewayCharges />{{rp|4}}

===Relationships===
Several typical relationships developed between umbrella IPs and their sub-IP clients. A sub-IP could be:<ref name=Williams-IPs />{{rp|99}}
* An independent supplier of information, with exclusive or partial editorial control and full or partial editing rights.
* An organisation making information available to an IP, sometimes on a [[Royalty payment|royalty]] basis.
* An organisation advertising on an IP's pages.
* An individual authoring articles or [[Column (periodical)|columns]] for an IP, usually on a royalty basis.

In addition, the IP [[Micronet 800]] used the sub-IP facility to offer the "Gallery" service, where a group, club, or individual could rent one or a number of frames cheaply, and for short periods if required.<ref name=LogOn7>{{
cite magazine
|magazine=Log On{{snd}}The magazine for Micronet members
|title=Gallery
|first=Julian
|last=Hayward
|issue=7
|pages=13{{ndash}}14
|date=Spring 1989
|publisher=Telemap
|location=London
|url=https://www.viewdata.org.uk/download.php?cat=15_Prestel&file=logon07.pdf#page=13
|archive-url=https://web.archive.org/web/20181115002855/https://www.viewdata.org.uk/download.php?cat=15_Prestel&file=logon07.pdf#page=13
|archive-date=15 November 2018
}}</ref>

An analysis in 1981 of the pros and cons of using an umbrella IP to publish information on Prestel concluded that if the owner of the information needed less than 500 frames, it would be cheaper to use an umbrella IP, but if over 5000, this would be more expensive than doing it themselves. In between these two figures, speed, convenience, and the need for design skills favoured using an IP, while going it alone assured confidentiality and provided more control.<ref name=Chapman-1981>
{{
cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|first=Tim
|last=Chapman
|chapter=Using an 'umbrella'
|pages=155{{ndash}}163
|chapter-url=https://archive.org/details/viewdatainaction0000unse/page/155/mode/2up?view=theater
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
|access-date=21 November 2024
}}</ref>{{rp|156{{ndash}}159}}

===Editing pages===
{{see also|#Network}}
[[File:Prestel Deccafax-viewdata-terminal +-Cherry-Editing-Keyboard.jpg|thumb|Cherry Editing Keyboard manufactured by [[Cherry_AG|Cherry GmbH]], connected to a Deccafax Viewdata Terminal Model VP1 manufactured (1979{{ndash}}1994) by Decca Radio & Television. ''Keyboard 11 x 50 x 31 cm, terminal 42 x 45 x 45 cm, 28 kg''<ref>
{{
cite web
|url=https://collection.sciencemuseumgroup.org.uk/objects/co34240/deccafax-viewdata-terminal-model-vp1-1979-1994
|title=Deccafax Viewdata Terminal Model VP1, 1979-1994, and Cherry Editing Keyboard
|website= Science Museum Group Collection Online
|publisher=[[Science Museum Group]]
|date=23 June 2014
|access-date=5 October 2024
|id=Object number 1994-1169: donated by [[House of Commons]]}}</ref>]]There were two ways to edit pages: directly, by creating or amending them using special editing keyboards while connected online to the main Update Computer; or offline, creating pages locally and uploading them in bulk. Bulk update required that pages be created offline using editing terminals that could store pages, or by using microcomputers. The pages were then either transmitted to the Update Computer online as a batch via a special dialup port and protocol, or sent on magnetic tape to the Update Centre (UDC), where they were uploaded.<ref name=BUS1981 />{{rp|2, 6{{ndash}}7}}

Using the online editor, IPs were also able to view information about a page hidden from ordinary users, such as the time and date of its last update, whether the frame was in a Closed User Group (CUG),{{refn||group=lower-alpha|name=CUG}} the price-to-view (if any), and the "frame count"{{snd}}the number of times the frame had been accessed.{{refn|group=lower-alpha|The frame count was not cumulated over all IRCs, but related only to the computer being viewed at the time: calculating national access counts was a manual exercise.}}

IPs and sub-IPs accessed the Edit computer using their normal ID and password, but had a separate password to access the editing facility. Bulk uploads only required the edit password and the IP's account number.

==Information and services==
Prestel's pre-launch promotional material focused on the general public:{{blockquote|Prestel is for everyone. Busy mothers can check out prices before they go shopping or their children can use Prestel to help them with their homework. Gardeners will have a constant source of information on what they should be doing at any particular time of the year. Whole families can choose and even book their holidays through Prestel. [..] Prestel will provide you with listings for theatres, cinemas, sporting events, exhibitions and just about anything else 
that may be going on.<ref name=PrestelBrochure1979>
{{
cite document
|title=Prestel
|date=January 1979
|type=brochure
|publisher=[[BT Group#Post Office Telecommunications|Post Office Telecommunications]]
|location=London
}}</ref>{{rp|3}}}} When the service launched in late 1979, [[BT Group#Post Office Telecommunications|Post Office Telecommunications]] had a [[Management style#Laissez-faire|hands-off approach]] towards managing whatever IPs placed on the system.<ref name=ButlerCox1985>
{{
cite web
|url=https://archivesit.org.uk/wp-content/uploads/2021/09/BCF-MISC-01-1985-Iss1.pdf
|access-date=17 October 2024
|title=Videotex in Europe
|date=January 1985
|author=Butler Cox
|publisher=Butler Cox & Partners
|location=London
|series=Butler Cox Report Series #19
|website=Archives of IT
|oclc=12808197
}}</ref>{{rp|25}} <!--Prestel did not attract many users.<ref name=Davenport2023>
{{
cite journal
|first=Lucinda D.
|last=Davenport
|date=2023 
|title=The Viability of Viewdata as a Mass Medium: A Case Study of Prestel, the Prototype for Computerized Information Systems, the Internet 
|url=https://tmgonline.nl/articles/845/files/65eb1b51170ea.pdf
|journal=TMG Journal for Media History
|issn=1387-649X
|volume=26 
|issue=2 
|pages=1{{ndash}}29 
|doi=10.18146/tmg.845 
|access-date=17 October 2024 }}</ref>{{rp|2}}-->This changed in early 1980, when [[BT Group|British Telecom]] (its successor) started targeting the business, professional and [[Hobby#Hobbyists|hobbyist]] markets via [[joint venture]]s with companies and organisations with specialised expertise.<ref name=ButlerCox1985 />{{rp|25}} 

===Specialised services===
By the mid-1980s, the specialised services on Prestel included:<ref name=Handbook1987 />{{rp|15{{ndash}}18}}
*''Prestel CitiService'', involving the [[London Stock Exchange]] and ICV Information Systems, targeted three groups: the business community as a whole, with mainly company information; private investors in a closed user group{{refn|group=lower-alpha|name=CUG}}, offering regularly updated share prices; and for brokers and other investment professionals, continuously updated share prices, also in a closed user group.<ref name=CitiService-News>
{{
cite news
|newspaper=CITINEWS : The newsletter of Prestel CitiService
|title=CitiService doubles its speed to meet demand 
|date=Winter 1985{{ndash}}1986
|page=1
|volume=1
|issue=3
|publisher=ICV Information Systems
}}</ref>

*''British Telecom Travel Service'' provided travel agents with information from tour operators, airlines, and other transport operators, and enabled online reservations. Services for other users included flight arrivals and departures, car rental, and exchange rates.

*''Prestel Farmlink'' packaged information for farmers from the [[Ministry of Agriculture, Fisheries and Food (United Kingdom)|Ministry of Agriculture, Fisheries and Food]], the [[Meat and Livestock Commission]], the [[Met Office|Meteorological Office]], and others. A link to Prestel CitiService provided farm commodity prices, and farmers could calculate, online, weekly wages and the formulation of feedstuffs.<ref name=FarmlinkCMA1985>
{{
cite book
|title=Centre of Management in Agriculture Yearbook 1984/1985
|date=June 1985
|url=https://www.iagrm.com/content/large/journals/cma/1984-85/centre-of-management-in-agriculture-yearbook-1984-85-lowres.pdf#page=67
|chapter=Prestel Farmlink
|first=Thea
|last=James
|pages=65,&nbsp;67
|via=Institute of Agricultural Management
|access-date=30 November 2024
}}</ref>

*Banking: the [[Nottingham Building Society]] offered Homelink, and the [[Bank of Scotland]] HOBS, the Home & Office Banking Service.<ref name=BoSHomeBankAd>
{{
cite newspaper The Times
|title=New from Bank of Scotland. Home Banking throughout the UK.
|date=23 February 1985
|at=p. 29: full-page advertisement showing six types of banking transactions on Prestel pages
|department=Family Money
|issue=62070
|url=https://www.thetimes.com/tto/archive/page/1983-04-26/22.html
}}</ref> Subscribers were provided with free or subsidised Prestel terminals.
 
*''Prestel Microcomputing'' offered downloadable software ([[telesoftware]]), noticeboards, newsletters, and reviews. It incorporated [[Micronet 800]] from [[Ascential|EMAP]], Viewfax 258, and Clubspot 810.<ref name=MicroLaunchLetter>
{{
cite document
|title=Prestel Microcomputing will add a new dimension to your home computing
|date=May 1984
|type=letter
|author=Prestel Microcomputing
|publisher=[[BT Group|British Telecom]]
}}</ref>

*''Prestel Education'' targeted schools and colleges, and provided course and careers advice, educational software, and help with using computers.<ref name=EducationTimes>
{{
cite newspaper The Times
|title=Schools given chance to plug into micro pages
|first=Bill
|last=Johnstone
|date=29 January 1985
|page=3
|issue=62048
|url=https://www.thetimes.com/tto/archive/page/1985-01-29/3.html
}}</ref>

*''British Telecom Insurance Services'' provided financial information to [[Insurance broker#In the United Kingdom|insurance intermediaries]] and enabled them to get online quotes from major insurance companies.<ref name=BTInsuranceGdn>
{{
cite news
|newspaper=[[The Guardian]]
|date=14 December 1987
|title=Ask me another: a new information service for the insurance industry
|first=Bob
|last=Rodwell
|page=22
|url=https://www.proquest.com/docview/186749481/
}}</ref>

*''Prestel Teleshopping'' was a specialised [[e-commerce]] service for the residential market, and involved [[Littlewoods]], [[Grattan plc|Grattan]], and [[Kays Catalogues]], among others.<ref name=TeleshoppingBTJ>
{{
cite journal
|journal=British Telecom Journal
|title=Armchair shopping delivers the goods
|first=Jane
|last=Young
|volume=8
|issue=2
|date=Summer 1987
|pages=76{{ndash}}77
|url=https://archive.org/details/btj-198707/page/n91/mode/2up
|access-date=30 November 2024
|issn=0260-1532
|oclc=8560549
|via=Internet Archive
}} Shows two "Kays Catalogues Teleshop" frames.</ref>

*''Prestel for Medical Practitioners'' packaged material from bodies such as the [[Royal College of General Practitioners]], the [[British Medical Association]], and the [[Department of Health and Social Security]] with drug data from pharmaceutical companies, information on [[Locum#United Kingdom healthcare|locum]] vacancies, conference and training diaries, and research news.<ref name=MedProgRep />

==Messaging==

===Response frames===
A "response frame" enabled a user to send a message to an IP using a preformatted page to order goods or services<ref name=Broadhead />{{rp|133}} or to transmit data.<ref name=MedDataCollect>
{{
cite journal
|journal=[[The BMJ#Editions|British Medical Journal (Clinical Research Edition)]]
|title=Use of a viewdata system to collect data from a multicentre clinical trial in anaesthesia
|first1=H. A.
|last1=Waldron
|first2=R. F.
|last2=Cookson
|volume=289
|issue=6451
|pages=1059{{ndash}}1061
|date=20 October 1984
|issn=0267-0623
|url=https://www.bmj.com/content/bmj/289/6451/1059.full.pdf
|access-date=9 December 2024
|doi=10.1136/bmj.289.6451.1059
|doi-access=free
}}
</ref> The user's name and other information needed (such as their address) were automatically added to the frame from their Prestel account details. 

Initially, response frames had to be collected by an IP from each IRC in turn; later, they were ingathered at the UDC, where the IP concerned could retrieve them. Eventually, with the introduction of Mailbox, response frames could be retrieved from any IRC. {{section link|#Network}}

===Mailbox===
[[Image:page-7.png|thumb|Launch version of Prestel Mailbox entry page, *7# (1983).]]
Prestel Mailbox was launched in 1983. Initially hosted on a computer in London, it was later made available UK-wide. {{section link|#Network}}

The entry page was *7#. This linked to pages where messages could be composed, stored messages retrieved, and standard, pre-formatted messages completed{{snd}}many designs were available, including greetings cards, invitations, and seasonal messages such as [[Valentine's Day#Celebration and status worldwide|valentines]].<ref name=Mbox1983UserGuide>
{{
cite web
|title=Mailbox, a Prestel Message Service : User Guide and Personal Directory
|type=booklet
|publisher=Prestel Message Services
|location=London
|date=1983
|at=See foot of pages A, B, C, E, F, I, M, T, and V.
|url=https://archive.org/details/prestel-mailbox-user-guide-1983/
|access-date=31 January 2025
|via=Internet Archive
}}</ref>

To prepare a basic message, a blank message page (*77#) was displayed, with the sender's Mailbox number pre-filled and blank fields for entering the recipient's number and the message text. There was space for about 100 words, and fewer if graphics were used. After addressing (with a Mailbox number) and writing the message, the user was offered the choice of keying 1 to send, or 2 to not send. Successful dispatch led to a confirmation page; if there were problems, such as a mistake in entering the recipient's number, an error message  was displayed.<ref name=Handbook1987>
{{
cite web
|url=https://archive.org/details/prestel-customer-handbook-1987/
|access-date=7 October 2024
|title=Prestel Customer Handbook
|date=1987
|author=British Telecom
|author-link=BT Group
|via=Internet Archive
}}</ref>{{rp|8}} Sending a message to more than one recipient meant re-keying the text into a new message page, although some microcomputers allowed the original message to be stored and then [[Cut, copy, and paste#Copy and paste|copy-pasted]].<ref name=BBCmicroPrestel1984 />{{rp|29}}
[[Image:Prestel-Mailbox message-received screenshot-1984.png |thumb|Screenshot of a received message. The name of the host computer is at top-right. The Mailbox numbers start with 01999, so are [[ex-directory]]. At bottom are instructions for storing or deleting the message.<ref>
{{
cite episode
|title=Using Prestel<!--title=describes general content. Actual title tbc: opening seconds missing. Or there may not be a specific title.-->
|series=Database
|date=7 June 1984
| minutes=3:08 |url=https://www.youtube.com/watch?v=szdbKz5CyhA |network=[[Thames Television|Thames TV]]
|season=<!--tbc-->
|number=<!--tbc-->
|last=Ashton
|first=Jane (host)
|via=YouTube
}}</ref>]]
Mailbox numbers were derived from the last nine digits of a user's phone number. For example, the Mailbox number for Prestel HQ, with the phone number 01-822-2211, was 018222211. Numbers were listed on page *486#. [[Telephone directory#Content|Ex-directory]] numbers were available on request.{{refn|group=lower-alpha|[[Telephone directory#Content|Ex-directory]] Prestel Mailbox numbers used a dummy phone number format starting with 01999 or 01111.{{citation needed|date=February 2017}}}}

[[Image:Prestel-Mailbox lapel-badge.png|thumb|Prestel Mailbox promotional badge, {{circa|lk=no}}1983. ''Metal, 5.6 cm diameter'']]When a user connected to Prestel, a banner on their Welcome page alerted them to any new messages, and when signing off via *90#, a warning would appear if any new messages had arrived in the meantime, with the option to read them before disconnecting. Messages were retrieved from page *930#, where they were presented in chronological order. After reading a new message, a user had to choose between deleting or saving it before the next message was presented. Three messages could be stored at a time, and were accessible via page *931#.

Using this first version of Prestel Mailbox was free of additional charges. {{See section|#Mailbox upgrade}}

====Simpatico====
[[Image:Prestel Simpatico index page on 4 September 1985.tif|thumb|''Simpatico'' entry page (1985).]]
''Simpatico'' was a free [[classified advertising|small ads]] service run by Prestel on page *787#. Users sent in their ads on a preformatted Mailbox page, with responses made via Mailbox. Ads were vetted and grouped under the headings of Heartsearch, Penpals, Interests & Hobbies, Meetings, Groups & Events, Friendsy (for younger users), and Life Begins At{{nbsp}}...<ref name=Simpatico-1984>
{{
cite magazine
|magazine=The Prestel Directory
|title=Simpatico
|date=1985
|issue=4
|at=p. 56 col 2
|publisher=Directel
|location=Birmingham
|issn=0266-0288
}}</ref>

===Telex Link===
Prestel Mailbox was extended in 1984 to give access to the [[Telex]] service via "Telex Link". On *8#, the Telex Link entry page, a message could be composed, the destination country chosen, and the telex number entered before sending the telex like a standard message. Telex Link added the necessary telex codes and tried to send the message several times before confirming receipt (or failure) via Mailbox. 

A telex could be sent to a Mailbox user from any telex terminal by using 295141 TXLINK G, the Telex Link number, as the telex address, and entering "MBX", followed by the Prestel user's Mailbox number, as the first line of the telex. An incoming telex appeared to the Prestel recipient as an ordinary Mailbox message, with the telex number of the sender added at the top of the screen. 

Sending a telex cost 50p for UK destinations, £1.00 for Europe, £2.00 for North America, £3.00 for elsewhere in the world, and £5.00 for sending to ships (via [[International Mobile Satellite Organization#INMARSAT|INMARSAT]]). There was no charge for receiving one.<ref name=TelexLink>
{{
cite web
|url=https://archive.org/details/Prestel-telex-link-info-sheet/
|access-date=7 October 2024
|title=Telex Link: Low Cost Access to Telex
|date=August 1986
|author=British Telecom
|author-link=BT Group
|via=Internet Archive
}}</ref> 

Telex Link was upgraded in 1987, with connections to more telex lines and faster delivery times, and its address changed to 934999 TXLINK G.<ref name=PrestelOfflineJan87>
{{
cite web
|archive-url=https://web.archive.org/web/20181115002850/https://www.viewdata.org.uk/download.php?cat=15_Prestel&file=PrestelOfflineJanuary1987.pdf
|archive-date=15 November 2018
|access-date=6 July 2025
|url=https://www.viewdata.org.uk/download.php?cat=15_Prestel&file=PrestelOfflineJanuary1987.pdf
|first=Dave
|last=King
|date=January 1987
|type=''Prestel Off Line'' newsletter
|title=Out with the old&nbsp;...
|location=London
|publisher=[[BT Group|British Telecom]]
|page=1
|via=[[Internet Archive]]
}}</ref>

===Mailbox upgrade===
A new messaging system was introduced in July 1989. This enabled messages up to five frames long, storing messages before sending, sending to multiple recipients (either individually or via a mailing list), message forwarding, and acknowledgment of receipt.<ref name=MboxUpgradeMicronetArticle>
{{
cite magazine
|magazine=Log On{{snd}}The magazine for Micronet members
|title=Mailbox Mark Two: so what's in it for you?
|issue=9
|pages=10{{ndash}}11
|date=Autumn 1989
|url=http://www.viewdata.org.uk/download.php?cat=15_Prestel&file=LogOn9Autumn1989.pdf#page=10
|archive-url=https://web.archive.org/web/20120227144353/http://www.viewdata.org.uk/download.php?cat=15_Prestel&file=LogOn9Autumn1989.pdf#page=10
|archive-date=27 February 2012
|access-date=5 July 2025
|via=[[Internet Archive]]
}} An interview with Prestel's Mailbox manager.</ref> Basic word-processing was also possible.<ref name=Mbox1989UserGuide>
{{
cite web
|title=Prestel Mailbox User Guide
|type=booklet
|publisher=Prestel
|location=[[Hemel Hempstead]]
|date=July 1989
|url=https://archive.org/details/prestel-mailbox-user-guide-1989
|access-date=30 January 2025
|via=Internet Archive
}}</ref>{{rp|16{{ndash}}17}} 

Sending a message without using any of these new facilities remained free: all the new options were charged at 1p per use per recipient. For the first time, sending [[E-mail spam|spam]] was permitted at a cost of 20p per message per recipient. In addition, the stored message facility was replaced by a summary page listing all the messages, both new and old, that were waiting: the user could then pick which message to view, rather than needing to read through them in chronological order.<ref name=MboxUpgradeCharges>
{{
cite web
|url=https://archive.org/details/prestel-upgraded-mailbox-charges-from-July1989/
|access-date=9 October 2024
|title=Mailbox Charges
|date=June 1990
|publisher=[[BT Group|British Telecom]]
|via=Internet Archive
}}</ref>

===Message statistics===
By 1984, Prestel users were sending messages at the rate of around 71,000 per month via a computer in London.<ref name=Rutter />{{rp|142}} The average number per month in early 1984 was 186,000, of which 125,000 were response frames and 61,000 Mailbox messages.<ref name=PrestelBriefingIssue-1>
{{
cite document
|title=Prestel Briefing
|date=April 1984
|at=Issue 1
|type=brochure
|publisher=Public Relations Department, Prestel
|location=London
}}</ref>{{refn|group=lower-alpha|The "Prestel Briefing" sources cited state that these figures "do not include activity conducted with external computers through Prestel Gateways".}}

In September 1985, after Mailbox became a national service, the chief executive of the part of British Telecom responsible for Prestel stated that 100,000 "electronic mail messages"{{snd}}Mailbox messages and response frames{{snd}}were being sent each week, with 60,000 terminals attached to the system.<ref name=Hooper1985>
{{
cite news
|newspaper=[[The Guardian]]
|date=26 September 1985
|title=Prestel's pride
|first=Richard
|last=Hooper
|page=17
|url=https://www.proquest.com/docview/186640055 
|id={{ProQuest|186640055}}
}}</ref> The average weekly figure rose to 130,000 in December 1985.<ref name=PrestelBriefingIssue-4>
{{
cite document
|title=Prestel Briefing
|date=February 1986
|at=Issue 4
|type=brochure
|publisher=Public Relations Department, Prestel
|location=London
}}</ref>
{{expand section|further statistics accompanied by citations|date=November 2024}}

===Hack===
A security breach of the Prestel mailbox of [[Prince Philip, Duke of Edinburgh]] occurred in November 1984<ref name=HackTimes>
{{
cite newspaper The Times
|title=Duke's mail code is cracked
|department=News
|date=6 November 1984
|page=2
|issue=61977
|column=3
|url=https://www.thetimes.com/tto/archive/article/1984-11-03/2/7.html
}}</ref> as part of a wider hack of Prestel.<ref name=HackBBC>
{{
cite web
|url=https://www.bbc.com/news/technology-36306419
|title=Archive of historic BT 'email' hack preserved
|website=BBC
|date=19 May 2016
|access-date=26 October 2024
}}</ref>

==Infrastructure==
===Terminals===
During the development phase of Prestel, British Telecom's research department produced a Prestel terminal specification. This formed the basis of design and [[type approval|type-approval]] discussions with, initially, manufacturers of TVs, and later with suppliers of other forms of terminal.<ref name=PrestelTermSpec1982>
{{
cite journal
|journal=British Telecommunications Engineering Journal
|title=Prestel terminals
|first=G. D.
|last=Hudson
|volume=1
|issue=1
|pages=35{{ndash}}41
|date=April 1982
|access-date=3 December 2024
|url=https://archive.org/details/bte-198204/page/n38/mode/1up
|issn=0262-401X
|via=Internet Archive
}} Pictured in the article are a [[Philips]] residential terminal equipped for Prestel, [[teletext]] and normal television reception, a [[Sony]] business terminal with message keyboard, a Zycor Prestel adaptor with a normal domestic television, and a Metrotech information provider editing terminal.</ref>

Several types of Prestel terminal were produced:<ref name=ButlerCox1985 />{{rp|75{{ndash}}77}}
* integrated residential terminals, typically based on television sets;
* integrated business terminals;
* adaptors for television sets;
* adaptors for microcomputers, with associated or standalone editing software;
* editing terminals.
===Network===
====Configuration and growth====
In March 1979, the [[BT Group#Post Office Telecommunications|Post Office]] launched a limited "London Residential Service" for subscribers in the capital. This was based on the computer used in an earlier test phase to both store the Prestel database and enable IPs to make updates to their pages.<ref name=StokesViewdataBook>
{{
cite book
|title=Viewdata: A Public Information Utility
|first=Adrian V.
|last=Stokes
|author-link=Adrian V. Stokes
|date=1980
|publisher=Input Two-Nine
|edition=2nd
|location=[[Purley, London|Purley]]
|isbn=978-0-905-89753-0
|oclc=6972310
}}</ref>{{rp|22{{ndash}}23}}

When the full commercial service launched in September 1979, three new computer centres were opened in London.<ref name=Broadhead />{{rp|130}} Two, known as Byron and Juniper, were "Information Retrieval Centres" (IRCs): their computers each contained a copy of the Prestel database, and were accessible by users. The third, Duke, was Prestel's "Update Centre" (UDC): IPs used this to create, modify or delete their pages, with their updates sent to the IRCs.{{refn|group=lower-alpha|The computer centres in London were first located in [[St Alphage House]], together with Prestel's National Operations Centre (NOC). The computers and the NOC were later moved to [[Baynard House, London|Baynard House]], which acted as a combined UDC and IRC. Both types of machine remained in service there till Prestel was discontinued in 1994.}} A fourth IRC, Dickens, opened in Birmingham in December.<ref name=Rutter />{{rp|115{{ndash}}116}}

IRCs were connected to the UDC in a [[star network]] configuration using leased-line connections (based on the [[X.25]] protocol) operating at 2400 [[baud]].<ref name=Scott>
{{
cite report
|first=Barry
|last=Scott
|date=September 1980
|title=Viewdata and Training: What, Where and How Much 
|page=7
|url=http://jesseheines.com:8080/~heines/academic/papers/1978dectechrpts/techrpt09.pdf
|publisher=[[Digital Equipment Corporation]] Educational Services
|publication-place=[[Burlington, Massachusetts|Burlington]]
|series=Technical Report No. 9
|access-date=8 October 2024
}}</ref> This network handled about 2,000 Prestel terminals and provided users with over 160,000 pages supplied by around 130 IPs.<ref name=Rutter>
{{cite thesis 
|first=Dorian James 
|last=Rutter 
|date=2005
|title=From Diversity to Convergence: British Computer Networks and the Internet, 1970{{ndash}}1995
|chapter=Chapter 4: Before the Internet: the Rise and Fall of Prestel
|pages=105{{ndash}}158
|chapter-url=https://wrap.warwick.ac.uk/id/eprint/1197/1/WRAP_THESIS_Rutter_2005.pdf#page=131
|degree=PhD
|publisher=[[University of Warwick]]
|url=https://wrap.warwick.ac.uk/id/eprint/1197/1/WRAP_THESIS_Rutter_2005.pdf
|oclc=93065596
}}</ref>{{rp|116}} By mid-1981, this arrangement had been replaced by dedicated X.25 circuits using the then-new [[Packet Switch Stream|PSS]] [[packet switching|packet-switched]] network and operating at 4.8&nbsp;kbit/s. Each IRC typically housed two information retrieval computers, though some in London had a single machine. IRCs were usually located in [[telephone exchange]]s.<ref name=Broadhead />{{rp|130}}

By June 1980, the network had grown to four individual information-retrieval computers in London, and six others installed in pairs in each of Birmingham, Edinburgh and Manchester, making ten in all.<ref name=NTIA>
{{
cite report
|date=October 1980
|title=Videotex Systems and Services
|first1= L. R.
|last1=Bloom
|first2=A. G.
|last2=Hanson
|first3=R. F.
|last3=Linfield
|first4= D. R.
|last4=Wortendyke
|chapter=Section 2.2: The United Kingdom
|page=18
|publisher=[[United States Department of Commerce|U.S. Department of Commerce]]
|location=[[Boulder, Colorado|Boulder]]
|id=NTIA Report 80-50
|url=http://www.its.bldrdoc.gov/pub/ntia-rpt/80-50/80-50.pdf
|archive-url=https://web.archive.org/web/20110606112803/http://www.its.bldrdoc.gov/pub/ntia-rpt/80-50/80-50.pdf
|archive-date=6 June 2011
|access-date=8 October 2024}}</ref> 
These ten computers could initially connect to around 1000 user ports, expandable to 2000.<ref name=Broadhead />{{rp|130}} At this point, the Prestel database contained about 164,000 pages with expandability to up to 260,000 built in: allowing for system management pages, this arrangement capped the size of the public database at around 250,000 frames.<ref name=Broadhead />{{rp|133}}

By September 1980, there were five IRC machines in London and pairs of machines in Birmingham, Nottingham, Edinburgh, Glasgow, Manchester, Liverpool and Belfast, offering a total of 914 user ports. Further IRCs were planned in Luton, Reading, Sevenoaks, Brighton, Leeds, Newcastle, Cardiff, Bristol, Bournemouth, Chelmsford and Norwich by the end of 1980.<ref name=Scott /> By the end of 1980, 1500 user ports were available.

As of July 1981, the number of IRC computers had grown to 18: this increased the percentage of phone subscribers who could access Prestel at [[local call]] rates from 30% to 62%.<ref name=Broadhead />{{rp|129}} In April 1984, Prestel announced that this had risen to 94%,<ref name=PrestelBriefingIssue-1 />{{rp|3}} and in February 1986, to 98%.<ref name=PrestelBriefingIssue-4 />{{rp|4}}

====International access====
In late 1981, an IRC called Jefferson opened in [[Boston|Boston, Massachusetts]], giving US subscribers access to Prestel via the American [[Telenet]] packet-switched network.<ref name=USaccess>
{{
cite journal
|journal=[[InfoWorld]]
|issn=0199-6649
|title=Prestel starts operation in the United States
|volume=4
|issue=5
|pages=1,&nbsp;6
|date=8 February 1982
|first=David
|last=Needle
|url=https://books.google.com/books?id=eD4EAAAAMBAJ&pg=PA1
}}</ref><ref name=BTJwinter81-82>
{{
cite journal
|journal=British Telecom Journal
|issn=0260-1532
|title=Prestel news
|volume=2
|issue=4
|page=35
|date=1981–1982
|oclc=8560549
<!--|url=http://www.samhallas.co.uk/repository/journals/BT_Journal/BTJ%20Vol%202%20No%204%20Winter%201981-2.pdf-->
}}</ref>

====Mailbox computer====
{{see also|#Mailbox}}
Mailbox, the Prestel messaging service, was launched on Enterprise computer, and allowed messaging only between users accessing that machine. By 1984, Mailbox had been rolled out nationwide using a dedicated computer in London known as Pandora.<ref name=MboxUpgradeMicronetArticle />{{rp|11 col 1}}

===Hardware===
Prestel's computers were based on the [[GEC 4000 series]] [[minicomputer]]. The main IRC machines were originally model [[GEC 4000 series#Models|GEC 4082s]] equipped with 384&nbsp;Kbyte [[magnetic-core memory|memory-core store]]s, six 70&nbsp;Mbyte [[hard disk drive]]s, and 100 [[Computer port (hardware)|ports]].{{refn|group=lower-alpha|By 1981, this configuration had changed: memory was doubled to 768&nbsp;kbytes<!-- [unknown previous editor] I welcome corrections to this, but the previous paragraph was in Kilobytes, and this is in Megabytes, and given the era I think it was probably kilobytes...--> and data discs reduced to six (corresponding to the number at the IRC machines), with a single transaction disc.<ref name=Broadhead />{{rp|131}}}} This set-up accommodated an initial 1500 Prestel users. 

Each IRC computer had 208 [[Computer port (hardware)|ports]]. With eight reserved for testing and control, a computer could support up to 200 simultaneous Prestel users. For the ordinary user, access was via an [[Asynchronous serial communication|asynchronous]], [[Duplex (telecommunications)|duplex]] interface provided by banks of  [[multiplexer]]s. These, in turn, were accessed via standard [[modem]]s, operating at 1200/75 bit/s, directly connected to the [[public switched telephone network|public phone network]].<ref name=Broadhead />{{rp|130}}

Besides the [[multiplexer]]s required to support 1200/75 dial-up access, the Update Centre machines were also connected to special [[modem]]s that handled online bulk updating by IPs. Banks of 300/300 bit/s full-duplex asynchronous [[ITU-T V.21|V.21]] [[modem]]s supported direct IP-computer-to-Prestel-computer links, while 1200 bit/s half-duplex [[ITU-T V.23|V.23]] [[modem]]s supported access by IPs using editing terminals that stored frames offline before uploading them. In addition, twin 9-track NRZI [[tape drive|tape decks]] of 800 bytes/inch capacity were provided for bulk offline updates.<ref name=Broadhead />{{rp|131}}
[[File:GEC4000computerRoom.png|thumb|GEC 4000 series computers at GEC Computers' Dunstable Development Centre, 1991]]
Though categorised as a [[minicomputer]], [[GEC 4000 series]] machines were large: one occupied several standard [[computer cabinet]]s each standing {{convert|6|ft|m}} high by {{convert|2|ft|m}} wide. The [[Storage Module Device|CDC 9762]] [[hard disc drive]]s were housed separately in large, stand-alone units about the size of a domestic washing machine.{{refn|group=lower-alpha|The 70&nbsp;Mbyte capacity [[hard disk drive|hard discs]] were removable. Each consisted of a stack of five, {{convert|14|in|adj=on|cm}} diameter [[Hard disk drive platter|platters]], standing {{convert|4|in|cm}} high, that could be lifted in and out of the drive unit.}} A GEC machine cost over £200,000 at standard prices, in addition to which were the costs of the associated communications equipment. Combining the two to assemble a single IRC was a major undertaking, and took some 15 months from order placement to commissioning.<ref name=Broadhead />{{rp|132}}

===Software===
[[GEC 4000 series]] computers could run on several [[operating system]]s. The Prestel machines used [[OS4000]], which was developed by GEC and supported [[GEC 4000 series#Babbage|BABBAGE]], the [[high-level assembler]] in which all Prestel software was written.

The pilot-trial system had five core software components: {{sc|input}} process, {{sc|output}} process, {{sc|gate-keeper}} process, {{sc|disc}}-handler process, and several {{sc|task}} processes. {{sc|input}} received data from a Prestel user; {{sc|gate}} accepted characters, one at a time, from {{sc|input}} and fed them to a {{sc|task}}; the key frame-getter {{sc|task}} fetched a fresh page or the next frame of an already-displayed page from {{sc|disc}}. {{sc|output}} then displayed a whole frame, preceded by a clear-screen command, to the user.<ref name=ClarkeViewdataDesign>
{{
cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|first=Keith
|last=Clarke
|chapter=The design of a viewdata system
|pages=33{{ndash}}55
|chapter-url=https://archive.org/details/viewdatainaction0000unse/page/33/mode/2up?view=theater
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
|access-date=18 November 2024
}}</ref>{{rp|43{{ndash}}52}}

The commercial service had several important additional functions, including an editing program and bulk update facilities, closed user groups,{{refn|group=lower-alpha|name=CUG}} messages, user billing and IP revenue allocation, optional additional user passwords, error-reporting routines, system manager facilities, and statistics-collecting routines.<ref name=ClarkeViewdataDesign />{{rp|52{{ndash}}53}}  

In 1987, a Prestel Admin computer was introduced to support the user registration process. It captured a new user's details from the paper Prestel application form, transferred the data to the relevant Prestel computer, and then printed the welcome letter to be sent to the user concerned.{{refn|group=lower-alpha|The Prestel Admin computer, which was also based on [[GEC 4000 series#Models|GEC 4082]] equipment, was the first to be equipped with the 1&nbsp;Mbyte of memory needed to support the use of the [[Logica#Software Products Group, Rapport, and_Xenix|Rapport]] [[relational database]] product supplied by [[Logica]].}}

===Monitoring===
Users' connections to Prestel were monitored by a device known as VAMPIRE{{snd}}Viewdata Access Monitor and Priority Incident Reporting Equipment. Via private circuits connected to an IRC computer's [[computer port (hardware)|ports]], this produced a continuously updated display on a monitoring screen at the Prestel Regional Centre responsible for an IRC.<ref name=Broadhead />{{rp|131}} The screen showed a matrix of small squares, each corresponding to a port on an IRC computer. Free ports were green, occupied ones yellow, incoming calls-to-connect by Prestel users were pale blue, and faulty ports red. In this way, the overall status of an IRC machine could be summarised and seen at a glance.

The response time of the Prestel system was measured by a microcomputer-based device known as PET. This monitored frame retrieval times for users and how quickly frame-editing commands issued by IP editors were implemented. PET operated in conjunction with a hardware performance monitor that recorded [[central processing unit]] and [[hard disk drive|disk-drive]] usage.<ref name=BTJ-Cantwell1982>
{{
cite journal
|journal=British Telecommunications Engineering
|issn=0262-401X
|title=Monitoring the Technical Performance of a National Videotex Network
|last1=Cantwell
|first1=B. D.
|last2=Clarke
|first2=K. E.
|last3=Steel
|first3=G. J.
|volume=1
|issue=3
|date=October 1982
|pages=150{{ndash}}154
|oclc=8735559
}}</ref>{{rp|152{{ndash}}154}}

==International sales==
Prestel software and [[Procedural knowledge|knowhow]] was sold to the state [[Postal, telegraph and telephone service|PTT]]s of several countries, including Austria,<ref name=SaleAustria>
{{
cite news
|newspaper=[[The Guardian]]
|date=4 July 1980
|title=Austria joins Prestel buyers
|page=14
|url=https://www.proquest.com/docview/186273649
|id={{ProQuest|186273649}}
}}</ref> Australia,<ref name=SaleAustralia>
{{
cite news
|newspaper=[[The Guardian]]
|date=15 June 1984
|title=Australia goes for Prestel
|first=Peter
|last=Large
|page=18
|url=https://www.proquest.com/docview/186451213/
|id={{ProQuest|186451213}}
}}</ref> former [[West Germany]],<ref name=SaleWestGermany>
{{
cite newspaper The Times
|title=Post Office sells Viewdata system to West Germans
|first=Michael
|last=Brown
|department=Business news
|date=24 August 1977
|page=19
|issue=60090
|column=4
|url=https://www.thetimes.com/tto/archive/article/1977-08-24/19/11.html
|quote=The West German Post Office will be supplied with a duplicate of the Viewdata computer programmes {{sic}} and expertise, and a trial system will be set up with the guidance of the British Post Office.
}}
</ref> the then-British colony of [[British Hong Kong|Hong Kong]],<ref name=ButlerCox1982 />{{rp|7, 8}} Italy,<ref name=SaleItaly>
{{
cite magazine
|magazine=The Prestel Directory
|title=Italy chooses GEC and Prestel
|page=74
|date=1986
|issue=1
|publisher=Directel
|location=Birmingham
|issn=0266-0288
}}</ref> Malaysia,<ref name=SaleMalaysia>
{{
cite newspaper The Times
|title=Malaysia orders GEC videotext system
|first=Clive
|last=Cookson
|department=Business news
|date=26 April 1982
|page=22
|issue=61516
|column=1
|url=https://www.thetimes.com/tto/archive/page/1983-04-26/22.html
}}</ref> the Netherlands,<ref name=StokesViewdataBook />{{rp|24}}
Singapore,<ref name=SaleSingapore>
{{
cite journal
|journal=British Telecom Engineering
|issn=0262-401X
|title=Prestel for Singapore [press release]
|volume=4
|issue=2
|page=98
|date=July 1985
|oclc=8735559
}}</ref> and Switzerland.<ref name=StokesViewdataBook />{{rp|25}} A private telecommunications company, [[GTE]], bought the system in the USA.<ref name=StokesViewdataBook />{{rp|25}}

==See also==

<!--Use {{Annotated link}} template-->
<!--List in alphabetical order of first word of each item-->

*{{annotated link|Bildschirmtext}}
*{{annotated link|Micronet 800}}
*{{annotated link|Minitel}}
*{{annotated link|Singapore Teleview}}
*{{annotated link|Telidon}}
*{{annotated link|videotex}}
*{{annotated link|Viewtron}}

==Notes==
{{reflist|group=lower-alpha}}

==References==
{{reflist}}

==Further reading==

<!--Sort by date: most recent first -->
<!--Use citation templates -->
<!--Add one-sentence description -->

* {{cite journal
|first=Lucinda D.
|last=Davenport
|date=2023 
|title=The Viability of Viewdata as a Mass Medium: A Case Study of Prestel, the Prototype for Computerized Information Systems, the Internet 
|journal=TMG Journal for Media History
|issn=1387-649X
|volume=26 
|issue=2 
|pages=1{{ndash}}29 
|doi=10.18146/tmg.845 
|doi-access=free 
}} Examines the development, marketing, and public reception of Prestel within the [[platform economy|digital platform economy]] emerging at the time.

* {{cite book
|first=Tom
|last=Lean
|title=Electronic dreams: how 1980s Britain learned to love the computer
|date=2016
|publisher=[[Bloomsbury Publishing|Bloomsbury Sigma]]
|location=London
|chapter=Chapter 6: Two Information Revolutions That Weren't
|chapter-url=https://books.google.com/books?id=RNaHCgAAQBAJ&pg=PA143
|pages=143{{ndash}}174
|isbn=978-1-47291-833-8
|oclc=944121056
|url=https://books.google.com/books?id=RNaHCgAAQBAJ
}} The chapter covering Prestel describes its history in the context of the 1980s boom in Britain of home computing, and has a particular focus on marketing strategies.

* {{cite book
|first=Raymond
|last=Williams
|author-link=Raymond Williams
|editor-first=Ederyn
|editor-last=Williams
|editor-link=Ederyn Williams
|title=Television: Technology and Cultural Form
|edition=2nd (reprinted)
|date=2010
|orig-date=1st ed. 1974, 2nd ed. 1990
|publisher=[[Routledge]]
|location=London
|isbn=978-0-415-31456-5
|oclc=846446460
}} Surveys the [[social history]] of television as a developing technology and the [[social history]] of how what was developed was used; anticipates{{snd}}from a mid-1970s perspective{{snd}}potential innovations (including "interactive devices"); and provides an overview of the situation in 1990.

* {{cite thesis 
|first=Dorian James 
|last=Rutter 
|date=2005
|title=From Diversity to Convergence: British Computer Networks and the Internet, 1970{{ndash}}1995
|chapter=Chapter 4: Before the Internet: the Rise and Fall of Prestel
|pages=105{{ndash}}158
|chapter-url=https://wrap.warwick.ac.uk/id/eprint/1197/1/WRAP_THESIS_Rutter_2005.pdf#page=131
|degree=PhD
|publisher=[[University of Warwick]]
|url=https://wrap.warwick.ac.uk/id/eprint/1197/1/WRAP_THESIS_Rutter_2005.pdf
|oclc=93065596
}}  Analyses the evolution of British computer networks and the Internet between 1970 and 1995, with the Prestel chapter focusing on Prestel's communications infrastructure, how this enabled the services offered, and marketing decisions and campaigns.

* {{cite book
|editor-first=Rex
|editor-last=Winsbury
|editor-link=Rex Winsbury
|first1=Alex
|last1=Reid
|first2=Keith
|last2=Clarke
|first3=Robbie
|last3=Robbie
|display-authors=2
|title=Viewdata in Action : a Comparative Study of Prestel
|date=1981
|publisher=[[McGraw-Hill]]
|location=London
|isbn=978-0-070-84548-0
|oclc=715473323
|url=https://archive.org/details/viewdatainaction0000unse
|url-access=registration
}} This multi-authored work covers relations between the interest groups involved in providing a videotex service on Prestel, videotex's impact on the press, editorial issues, economic aspects, and likely technological developments.

*{{cite book
|first=Rex
|last=Winsbury
|author-link=Rex Winsbury
|title=The Electronic Bookstall : Push-button publishing on videotex: a critical study of Prestel in Britain
|date=1979
|publisher=International Institute of Communications
|location=London
|isbn=978-0-904-77610-2
|oclc=5507588
|url=https://archive.org/details/electronicbookst0000wins
|url-access=registration
}} Focuses on the practicalities and economics of creating information on Prestel, and on Prestel's relationships with the British [[History of British newspapers#Developments|newspaper]] and broader print publishing industry of the late 1970s.

*{{cite book
|first1=Samuel
|last1=Fedida
|author1-link=Samuel Fedida
|first2=Rex
|last2=Malik
|title=The Viewdata Revolution
|date=1979
|publisher=Associated Business Press
|location=London
|isbn=978-0-852-27214-5
|oclc=6387998
|url=https://archive.org/details/viewdatarevoluti0000fedi/
|url-access=registration
}} Co-authored by one of Prestel's inventors, [[Samuel Fedida]], this describes the genesis and context of [[viewdata]], the components of the initial Prestel service, and potential developments from the perspective of 1979.

==External links==
*[https://archive.org/details/creativecomputing-1983-05./page/n127/mode/2up?view=theater A User's View of Prestel] in an archived copy of ''[[Creative Computing (magazine)|Creative Computing]]'' magazine

*[https://www.viewdata.org.uk/index.php?cat=15_Prestel Prestel] at ''Celebrating the Viewdata Revolution''

*Objects catalogued under [https://collection.sciencemuseumgroup.org.uk/search/categories/telecommunications?q=prestel "telecommunications /Prestel"] and [https://collection.sciencemuseumgroup.org.uk/search/categories/computing-&-data-processing?q=prestel "computing & data-processing /Prestel] in the [[Science Museum Group]]'s collections

*[https://www.digitalarchives.bt.com/CalmView/Overview.aspx?src=CalmView.Catalog&r=(((Title=%27Prestel%27))) Catalogue records with "Prestel" in the title] in [[BT Group]]'s digital archives

{{Videotex}}
{{BT Group}}
{{Telecommunications industry in the United Kingdom}}
{{Telecommunications}}

[[Category:BT Group]]
[[Category:History of telecommunications in the United Kingdom]]
[[Category:Legacy systems]]
[[Category:Pre–World Wide Web online services]]
[[Category:Videotex]]