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Prestel (abbrev. from press telephone), the brand name for the UK
Post Office Telecommunications Post Office Telecommunications was set up as a separate department of the UK Post Office, in October 1969. The Post Office Act 1969 was passed to provide for greater efficiency in post and telephone services; rather than run a range of services, ...
's Viewdata technology, was an interactive
videotex Videotex (or interactive videotex) was one of the earliest implementations of an end-user information system. From the late 1970s to early 2010s, it was used to deliver information (usually pages of text) to a user in computer-like format, typi ...
system developed during the late 1970s and commercially launched in 1979. It achieved a maximum of 90,000 subscribers in the UK and was eventually sold by BT in 1994. The technology was a forerunner of on-line services today. Instead of a computer, a television set connected to a dedicated terminal was used to receive information from a remote database via a telephone line, although a computer with a
modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more c ...
and running
Terminal emulator A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term ''terminal'' covers all remote term ...
software can be used if the user so inclined. The service offered thousands of pages ranging from consumer information to financial data but with limited graphics.


Initial development

Prestel was created based on the work of Samuel Fedida at what was then known as the Post Office Research Station in Martlesham,
Suffolk Suffolk () is a ceremonial county of England in East Anglia. It borders Norfolk to the north, Cambridgeshire to the west and Essex to the south; the North Sea lies to the east. The county town is Ipswich; other important towns include ...
. In 1978, under the management of David Wood the software was developed by a team of programmers recruited from within the Post Office Data Processing Executive. As part of the privatisation of
British Telecom BT Group plc (trading as BT and formerly British Telecom) is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, b ...
, the team were moved into a "Prestel Division" of BT.


Database

A Prestel ''database'' is commonly referred to as the ''tree structure''. The structure is shown pictorially as an inverted tree with the data considered as ''leaves'' of the tree, accessed via ''branches'' which serve as a means of classifying the information. There exists quite a lot of jargon regarding such structures but in order to appreciate the concept it is necessary to mention just the ''node'', ''page'' and ''frame''. Nodes are the junction pages in the tree at which a number of choices can be made leading to other nodes or to the information itself. Pages are the final levels in the tree and contain the actual data—these may be divided into frames which are really screenfuls of information. The public Prestel database consisted of a set of individual frames, which were arranged in 24 lines of 40 characters each, similar to the display used by the
Ceefax Ceefax (, punning on "seeing facts") was the world's first teletext information service and a forerunner to the current BBC Red Button service. Ceefax was started by the BBC in 1974 and ended, after 38 years of broadcasting, at 23:32:19 BST ...
and
ORACLE An oracle is a person or agency considered to provide wise and insightful counsel or prophetic predictions, most notably including precognition of the future, inspired by deities. As such, it is a form of divination. Description The word ...
teletext services provided by the BBC and ITV television companies. Of these, the top line was reserved for the name of the Information Provider (IP), the price and the page number, and the bottom line was reserved for system messages. Thus there remained 22 lines (of 40 characters each) in which the IP could present information to the end user. A page should be considered as a logical unit of data within the database and the frame a physical unit. Unfortunately the terms node, page and frame are often used synonymously which may lead to some confusion. To the user of course a node is the same as a page and they are both identified by a page number. To access a particular item of information, a simple progression down through the nodes to the page is all that is required, and then the frames of that page can be stepped through. This is facilitated by each node displaying up to ten choices, one of which may be taken by the user responding with the appropriate digit from 0 to 9. This simple method of access may be thought of as a question and answer session: the computer displays a question 'Which of the ten choices do you want to make?’ and the user replies with the appropriate digit. A choice of 9 at node 17 moves the user to page 179. The flexibility of this logical access method is increased firstly by allowing cross-referencing from one branch of the tree to another and secondly by providing a few simple commands available to the user for accessing certain pages directly. While this principle had considerable advantages in user simplicity and computer efficiency over the "keyword/thesaurus principle" used in many other systems, it has two very real disadvantages which have now been recognized: lack of flexibility and slowness. Page numbers were from one to nine digits in length (i.e., in the range 0 to 999999999) Acorn User Guide 1984 created in a tree like structure, whereby lower level pages could only exist if the higher numbered parent pages had already been created. Hacker's Handbook 1994. Thus creating page 7471 required pages 747, 74 and 7 to exist, but generally the three digit node 747 would have been created in order to register the relevant main IP account. Single and double digit pages were special pages reserved by Prestel for general system information purposes, as were the 1nn-199nn sets of three digit nodes; e.g., page 1a was the standard Prestel Main Index. Pages starting with a 9 were for system management functions, and were limited to three digits in length; e.g., page 92 showed details of the user's Prestel bill, and page 910 gave IPs access to online editing facilities. Available characters consisted of upper and lower case alphanumeric characters as well as punctuation and simple arithmetic symbols, using a variant of
ISO 646 ISO/IEC 646 is a set of ISO/IEC standards, described as ''Information technology — ISO 7-bit coded character set for information interchange'' and developed in cooperation with ASCII at least since 1964. Since its first edition in ...
and
CCITT The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...
standard. Prestel. The Technology 1980 This layout was later formalised in the 1981 CEPT videotex standard as the CEPT3 profile. By embedding cursor-control characters within the page data, it was also possible to encode simple animations by re-writing parts of the screen already displayed. These were termed "dynamic frames" and could not be created online using conventional editing terminals, but required specialist software and uploading via the "bulk update" facility. No timing options were available beyond that imposed by the available transmission speed, usually 1,200 bps. The IP logo on line 1 occupied at least 43 bytes, depending on the number of
control characters In computing and telecommunication, a control character or non-printing character (NPC) is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than th ...
, so the space available for the IP's data is 877 characters at most. Prestel Bulk Update Technical Specification 1984. Lines could either occupy the full forty character positions, or be terminated early with a CR/LF sequence. Each control character took up two bytes, despite displaying as a single space, so the more complex a page, the less actual information could be presented. It was almost impossible, therefore, to display a right hand border to a page. Routing from page to page through the database was arranged by the use of numbered items on index pages, which used the space in the frame routing table to map the index links directly to other page numbers. Thus an index on page 747 might have links requiring the user to key 1 for "UK Flights", key 2 for "Flights to Europe", or key 3 for "Hotels" which represented links to page 74781, 74782, and 74791 respectively. The routing table for a particular frame only allowed specification of routes for digits 0–9, so double digit routes would typically be sent via an "intermediate" frame, usually a spare frame elsewhere in the IP's database, to which the first digit of all similarly numbered items would link. Since pressing a number would interrupt a page that was currently being displayed, the keying of a double digit route would not generally inconvenience the viewer with the display of the intermediate frame. Pages did not scroll, but could effectively be extended by the use of frames, which required alphanumeric suffixes to be appended to the numeric page numbers. Thus keying page *7471# actually resulted in the display of frame 7471a which could be extended by use of follow-on frames 7471b, 7471c, etc., each of which was accessed by repeated use of the "#" key. Because the Prestel system was originally designed to be operated solely by means of a simple numeric keypad it was not possible to access frames other than the top level frame directly (i.e., in this case pages other than "7471a"). This follow-on frame facility was exploited extensively by the implementation of '' telesoftware'' on Prestel whereby computer programmes, notably for the
BBC Micro The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphas ...
, were available for download from Prestel. Generally speaking, the first two or three frames acted as header pages. For example, one such programme was described on frame 70067a and 70067b, while frame 70067c gave the number of subsequent frames containing the programme, and a crosscheck sum. Special software enabled this crosscheck sum to be compared with a value calculated from the result of downloading all the required frames in order to verify a successful download. The actual telesoftware programme started on frame 70067d. In the event that the check failed it was necessary to download the entire programme again starting from the beginning. Each frame had a single-character type code associated with it. Most frames would be "i" (for "Information" types) but other types included response frames, mailbox pages, or gateway pages. Special frame types could also be specified which caused the follow-on frame to be automatically displayed, with or without the usual clear-screen code, as soon as the current frame had finished being transmitted. These were mainly used by "dynamic frames", as it provided a mechanism to continue animations which would not otherwise fit within the number of characters available in a standard frame.


Views


Information providers

There were two levels of information provider (IP) – firstly a "Main IP" who rented pages from Post Office Telecommunications (PO)/British Telecom (BT) directly, and thus owned a three-digit node or "master page" in the database. This required an ongoing investment, consisting of a minimal annual payment to become an information provider. The price of this basic package was £5,500 per annum in 1983, Prestel IP Price List 1982, equivalent to around £29,000 in 2021. Measuring Worth 2021. The charge included: * the facility to enter and amend information and to retrieve response frames * 100 frames * capacity to store 10 completed response frames * editing training for staff (two-day seminar) * copy of IP editing manual; * annual print-out of frames in use (if required) * bulk update facilities (if required). Additional frames were available in batches of 500 for £500 per annum (over £2,600 in 2021) while Closed User Groups and Sub-IP Facility cost respectively £250 (over £1,300 in 2021). Those with smaller requirements or budget could rent pages from a main information provider rather than from the
Post Office A post office is a public facility and a retailer that provides mail services, such as accepting letters and parcels, providing post office boxes, and selling postage stamps, packaging, and stationery. Post offices may offer additional se ...
/
British Telecom BT Group plc (trading as BT and formerly British Telecom) is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, b ...
. The main IP had to pay an additional £250 to obtain the privilege but could then rent out individual pages at a market rate. Unlike the main IP, sub-IPs had to pay a per-minute charge for editing online, 8p per minute at Monday-Friday 8 am-6 pm or 8p per 4-minute in all other times for sub-IPs in 1983 (over 35p as at end 2014). Sub-IPs were restricted to pages under a 4 or more digit node within a Main IP's area, and could only edit existing pages. Sub-IP accounts were unable to create or delete pages or frames themselves. Editing of pages was possible in one of two ways, either directly by creating or amending pages using special editing keyboards whilst connected online to the main Update Computer, or by creating pages offline and updating them in bulk to the main Update Computer. Bulk update required that pages be created offline by the use of editing terminals which could store pages, or by micro-computers such as that provided by
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...
or
Acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera '' Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and b ...
. The pages were then transmitted to the UDC online in bulk via a special dialup port and protocol, or sent via magnetic tape to the Update Centre (UDC) where they were uploaded by Network Operations (NOC) staff. Using the online editor facility, IPs were also able to view information about their pages which was hidden from the ordinary end user, such as the time and date of the last update, whether the frame was in a Closed User Group (CUG), the price to view the frame (if any) and the "frame count" or number of times the frame had been accessed. The frame count was not accumulated over all IRC's but related only to the computer which was being viewed at the time so gaining 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 IPs account number.


Users

Having logged on, each user was taken direct to their default main index page, known as the ''Welcome Page''. For standard users, this would be page 1a, the general top level index to the whole of Prestel. However, if a user signed up through, or later joined, products or services from major IPs, such as Club 403, Micronet 800, Prestel Travel, CitiService, etc., they would be given a different welcome page, so that after logon they were routed directly to 800a, 403a, 747a etc. From the Welcome Page it was possible for any user to find pages of information in several different ways, or a combination of them. Printed directories were available which gave the full page numbers corresponding to the items in an alphabetical index. Pages were accessed directly by keying "*page number#". Individual pages often had links to related pages which could be accessed by use of one or two digit routing codes. This feature was widely used on sets of index pages which were commonly grouped by subject heading, provided both by the Post Office/BT and by individual IPs. Because of the numerical limitation, it was often necessary to go through a series of index pages in order to reach the desired page. Extension frames which might be required to view further information on a topic could be only accessed by use of the "#" key. From 1987 onwards, it became possible to use access Prestel pages via use of special alphabetic codes, provided that the IP who owned the page set up a special keyword mapped onto that page. Thus, by keying *M NEWS#, it was possible for a user to route directly to page *40111# to obtain news about micro-computers. Many standard mailbox frames were available offering various designs for greetings cards or seasonal messages such as Valentine Cards. Prestel Marketing Brochure 1984 Messages could only occupy a single frame, so the main message text field could typically take up to a maximum of 100 words, depending upon how many other fields were required and what graphics were used on the frame. Mailbox frames were completed by entering relevant details and pressing the # key on each field. Completing the last, or only, of which lead to the request to "KEY 1 TO SEND KEY 2 NOT TO SEND". Assuming all went well, this led to a subsequent final screen confirming successful dispatch, or if there were problems (such as a mistake in entering the Mailbox number) then an appropriate error frame was displayed. If it was desired to send the message to more than one recipient then it was necessary to re-key the message text into a fresh message frame, although some popular micro-computers of the time provided the facility to store the message so that it could be copied and pasted into a new message. Special commands were also available. For example, to facilitate movement around the database it was possible to step back through a maximum of 3 frames or pages by use of the special key combination "*#". In the event of corruption of a page in transmission it was possible to refresh the page by means of the code *00, which had the advantage of avoiding any page charge being raised again. Alternatively, if the user wished to update a page to see the latest information, for example of flight arrival times, the *09 command would retrieve the latest updates, at the same time re-billing any page display charge. If all else failed, a user could simply return to the first page which he saw after logging onto the system by use of the *0# combination, which brought up their default Main Index. Exceptionally, information could be hidden on a frame by an IP which could only be revealed by use of the 'Reveal" key of the keypad (e.g., to show an answer to a quiz). The same 'Reveal' key was also used to hide the data once more.


Infrastructure

With a view to supporting the planned major expansion programme, a new Prestel infrastructure was designed around two different types of data centre: Update Centre (UDC), where IPs could create, modify and delete their pages of information, and Information Retrieval Centre (IRC), which mirrored copy of the pages is provided to end-users. In practice there only ever was one Update Centre, and this always housed just one update computer, named "Duke", but within six months of public launch there were in addition two dedicated information retrieval computers. In those early days of the public service all the live Prestel computers were located in St Alphage House, a 1960s office block on Fore Street in the City of London. At the time the National Operations Centre (NOC) was located in the same building on the same floor. The computers and the NOC were later moved to Baynard House, (on Queen Victoria Street, also in the City of London) which acted as a combined UDC and IRC. Both types of machine, together with other development hardware, remained in service there until 1994 when the Prestel service was sold by BT to a private company. Each IRC normally housed two information retrieval computers, although in some IRCs in London just a single machine was present. IRCs were generally located within major telephone exchanges, rather than in BT Data Processing Centres, in order to give room for the extensive communications requirements. Exchange buildings were ideally suited to housing the large numbers of rack mounted 1200/75 baud modems and associated cabling as well as the racks of 16-port Multi-Channel Asynchronous Communications Control Units (MCACCUs) or multiplexors from GEC which gave the modems logical access into the computers. In the new infrastructure, IRCs were connected to the UDC in a star network configuration, originally via leased line permanent (not packet switched) connections, based on the
X.25 X.25 is an ITU-T standard protocol suite for packet-switched data communication in wide area networks (WAN). It was originally defined by the International Telegraph and Telephone Consultative Committee (CCITT, now ITU-T) in a series of drafts a ...
protocol, operating at 2.4 kilobits per second (kbit/s). DEC Educational Services 1981. By mid 1981, these private circuit links had been replaced with dedicated 4-wire X25 circuits over the new public
Packet Switch Stream In the United Kingdom, Packet Switch Stream (PSS) was an X.25-based packet-switched network, provided by the British Post Office Telecommunications and then British Telecommunications starting in 1980. After a period of pre-operational testing with ...
(PSS) network operating at 4.8 kbit/s. By June 1980, there were four singleton retrieval computers in London, plus six other machines installed in pairs at IRC sites in Birmingham, Edinburgh and Manchester. National Telecommunications & Information Administration 1980. Fully equipped IRC machines had a design capacity of 200 user ports each but these first ten machines were initially only capable of supporting approximately 1,000 users between them, expandable later to 2,000 users. By September 1980, there were five IRC machines in London plus pairs of machines at Birmingham, Nottingham, Edinburgh, Glasgow, Manchester, Liverpool and Belfast offering a total of 914 user ports. Further IRC's were planned at Luton, Reading, Sevenoaks, Brighton, Leeds, Newcastle, Cardiff, Bristol, Bournemouth, Chelmsford and Norwich by the end of 1980. In some of these locations where there was insufficient Prestel traffic to warrant siting an IRC computer, the plans were to site multiplex equipment in a suitable exchange building from where connections were made over X25 to the nearest proper IRC. As at the end of 1980, there was actually a total of 1500 live computer ports available and by July 1981, the number of IRC computers has been expended to 18, increasing the coverage of the telephone subscriber population from 30% to 62%. In 1982, using the multiplexor technique described above, a virtual IRC was created in Boston, Massachusetts giving access to a machine in the UK known as Hogarth in order to provide Prestel services to subscribers from across the United States via the Telenet packet switching network. InfoWorld 1981. The Prestel Mailbox service was originally launched on Enterprise computer to support messaging solely between users on that machine and by 1984, the facility had been rolled out nationwide. This required a further type of Prestel computer dedicated to the exchange of messages. The only example of this type, which became known as Pandora, was co-located with the UDC in Baynard House, London. Originally Prestel IRC computers were directly dialled by means of an ordinary telephone number (e.g., the Enterprise computer in Croydon was accessed by dialling 01 686 0311. By 1984, the special short dialling codes 618 and 918 were in use in order to give access to the nearest IRC at local telephone call rates, at least across most parts of the UK. In 1987, the entire local access network was being overhauled and shared with other Dialcom Group companies – users connecting and not automatically logging into Prestel would be greeted with a menu allowing access to Prestel, Telecom Gold, etc. Prestel Offline newsletter 1987.


Hardware and software

Prestel computers were based on
GEC 4000 The GEC 4000 was a series of 16/32-bit minicomputers produced by GEC Computers Ltd in the United Kingdom during the 1970s, 1980s and early 1990s. History GEC Computers was formed in 1968 as a business unit of the GEC conglomerate. It i ...
series ''
minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ' ...
'' with small differences in the accumulation according to the function of the machine. IRC main machines were originally GEC 4082 equipped with 384 Kbytes memory core store machines, six 70 Mbyte HDD and 100 ports for 1500 initial users. The network grew to the point that in June 1980 there were four stand-alone retrieval computers in the London area with six other computers installed in pairs in Birmingham, Edinburgh and Manchester. The ten computers could output to approximately 1000 user ports, expandable to 2000. The GEC 4082 computer with 512 megabyte capacity will interconnect to the 10 and later to 20 retrieval computers to handle the data files. The initial data base consists of approximately 164,000 information pages (June, 1980) with planned update capacity of 260,000 pages. A page consists of a maximum of 960 data characters (5x7 bits each, suggesting approximately 35,000 bits per page). This arrangement effectively limited the size of the public service
database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases ...
to around 250,000 frames so in order to cope with planned growth by 1981 the IRC machines had been expanded by the addition of two further data drives. Each IRC computer was configured with 208
ports A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as H ...
and so was able to support 200 simultaneous Prestel users, the remaining 8 ports being used for test and control functions. Access for the ordinary user was provided via the duplex
asynchronous Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal wit ...
interface provided by banks of GEC 16-port multi-channel asynchronous control units (MCACCU) known more simply as
multiplexer In electronics, a multiplexer (or mux; spelled sometimes as multiplexor), also known as a data selector, is a device that selects between several analog or digital input signals and forwards the selected input to a single output line. The sel ...
s. These devices in turn were accessed via banks of standard Post Office
Modems A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carr ...
No. 20 operating at 1200/75 bit/s, which were connected directly to the
public switched telephone network The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...
(PSTN). As seen in 1979, it had important strengths and weaknesses: "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." By 1981, this configuration had changed with memory doubled to 768 kbytes but with data discs reduced to six, corresponding to the number at the IRC machines and with just a single transaction disc. In addition to the MCACCU units required to support 1200/75 dial up access, the Update Centre machines were also connected to special modems provided to support online bulk updating by IPs. Banks of 300/300 bit/s full duplex asynchronous V21 modems supported computer to computer links for the more sophisticated IP while 1200 bit/s half duplex V23 modems supported so called intelligent editing terminals (i.e. those capable of storing a number of frames offline before uploading to the UDC). In addition twin 9-track NRZI tape decks of 800 bytes/inch capacity were provided in order to support bulk offline updates. Although technically categorised as ''
minicomputers A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
'', these GEC machines were physically very large by today's standards, each occupying several standard communications cabinets, each standing high by wide. The CDC 9762 hard disc drives were housed separately in large stand-alone units, each one about the size of a domestic washing machine. (See images in the photo of the GEC Computers' Development Centre). The 70 Mbyte capacity hard discs themselves were in fact removable units, each consisting of a stack of five 14-inch
platters The Platters was an American vocal group formed in 1952. They are one of the most successful vocal groups of the early rock and roll era. Their distinctive sound bridges the pre-rock Tin Pan Alley tradition and the new burgeoning genre. The ac ...
, standing high, that could be lifted in and out of the drive unit. The GEC machines cost in excess of £200,000 each at GEC standard prices, in addition to which there were the costs of all the associated communications equipment. Putting together all of the computer and communications equipment required for a single IRC was a major undertaking and took some 15 months from order placement to commissioning. GEC 4000 series computers were capable of running a number of operating systems but in practice Prestel machines exclusively ran
OS4000 OS4000 is a proprietary operating system introduced by GEC Computers Limited in 1977 as the successor to GEC DOS, for its range of GEC 4000 series 16-bit, and later 32-bit, minicomputers. OS4000 was developed through to late 1990s, and has be ...
which itself was developed by GEC. This in turn supported BABBAGE, the so-called high level assembler language in which all the Prestel software for both IRC and UDC machines (and later the messaging machine) was written. In 1987, a Prestel Admin computer was introduced which supported the user registration process: the capture of user details from the paper Prestel Application Form (PAF), the transfer of data to the relevant Prestel computer, and the printing of the welcome letter for users. This machine, also based upon GEC 4082 equipment, was the first to be equipped with 1 Mbyte of memory which was required to support the
Rapport Rapport () is a close and harmonious relationship in which the people or groups concerned are "in sync" with each other, understand each other's feelings or ideas, and communicate smoothly. The word stems from the French verb which means litera ...
relational database. This product from
Logica Logica plc was a multinational IT and management consultancy company headquartered in London and later Reading, United Kingdom. Founded in 1969, the company had offices in London and in a number of major cities across England, Wales and Sc ...
was an early example of deployment of a system written in a 4GL database language which supported all features of the Prestel Admin application.


Monitoring equipment

In order to proactively manage the potentially large numbers of user connections to Prestel computers, special monitoring equipment was developed by Post Office research and development engineers. This was known by the acronym VAMPIRE, short for ''Viewdata Access Monitor and Priority Incident Reporting Equipment'' – a title which more or less describes its function. The device used private circuits to connect modem ports on each computer or remote IRC multiplexor node, with a display on a television screen Prestel Prestel at the Regional Centre responsible for the administration of IRC. The VAMPIRE screen consisted of a matrix of small squares, so arranged that all ports for a single IRC computer could be displayed on a single television with each square representing the state of a port simply by means of the colour. Free ports were shown as green, occupied ports as yellow, incoming calls as pale blue and faulty ports as red, such that the state of a whole Prestel machine or concentrator node could be determined at a glance. It was apparently planned to extend this facility via a system designated the ''Data Recording and Concentrator Unit for Line Applications'' known as DRACULA, which would generate a summary view so that the state of multiple computers could be displayed on a single screen. This device was never deployed since the number of VAMPIRE sets needed to monitor every Prestel computer and concentrator never got beyond a couple of dozen, spread over many Regional Prestel Centre offices.


Messaging

In 1983, the Prestel messaging service known as "Prestel Mailbox" was launched, initially hosted on the computer known as "Enterprise", and later available from all IRC computers by means of a centralised messaging computer known as "Pandora". This facility extended the original day one concept of "Response Frames" whereby an end user could send a message back to the IP who owned the page via special pages, for example to order goods or services. The user's name, address, telephone number, and date could be added automatically to the message when the IP set up the response frame by means of codes which triggered extraction of key data from the users account held on the IRC computer. Initially response frames were ingathered by an IP from each IRC individually, but later the facility to collect messages from all IRCs at the UDC from where they could be ingathered centrally was implemented, and with the introduction of Mailbox, they could be retrieved from any IRC. In order to use the new Prestel Mailbox service, the user went to page *7# which gave access to a set of frames where new "free format" messages could be created, or pre-formatted messages filled out and stored messages could be retrieved, and other related facilities were hosted. Many standard mailbox frames were available offering various designs for greetings cards or seasonal messages such as Valentine Cards. In order to compose a new message, a blank message frame, which could also be accessed directly via *77#, was displayed with the sender's mailbox number pre-filled, leaving space for the recipient's mailbox number and the text of the message itself. Messages could only occupy a single frame, so the main message text field could typically take up to a maximum of 100 words, depending upon how many other fields were required and what graphics were used on the frame. Mailbox frames were completed by entering relevant details and pressing the # key on each field. Completing the last, or only, of which lead to the request to "KEY 1 TO SEND KEY 2 NOT TO SEND". Assuming all went well, this led to a subsequent final screen confirming successful dispatch, or if there were problems (such as a mistake in entering the Mailbox number) then an appropriate error frame was displayed. If it was desired to send the message to more than one recipient then it was necessary to re-key the message text into a fresh message frame, although some popular micro-computers of the time provided the facility to store the message so that it could be copied and pasted into a new message. Prestel Mailbox numbers were generally based upon the last 9 digits of the user's telephone number, without spaces or punctuation. For example, the Prestel Mailbox number for Prestel Headquarters which had the telephone number 01-822 2211 would be simply 018222211, while that for a user in Manchester with telephone number 061-228 7878 would be 612287878. In keeping with the established telephone number practice, but unlike the convention with today's internet mailboxes, Prestel Mailbox numbers were published by default, and were available via the Prestel computers in a dedicated directory accessible from page *486#. On request, '' ex-directory'' mailbox numbers were available, usually employing a dummy telephone number format such as the series 01999nnnn, and later the series 01111nnnn. Every time a user logged into Prestel, a Mailbox banner on their Welcome page, usually flashing, would alert them if they had any new messages waiting. Similarly, upon the user's request to sign off the system via *90#, a warning would appear if any new messages had arrived, with an option to read them, before the user was allowed to disconnect. Messages were retrieved from page *930#, where they were presented to the recipient in chronological order. After reading a new message, the user had to choose between deleting the message, or saving it, before the next message was presented. Initially only three messages could be saved at any one time, and these stored messages were accessible via page *931#. Use of the basic Mailbox service was free, that is to say there were no registration charges for owning a mailbox, or for sending new messages or for storing received messages, although even by 1984 only five messages could be saved once they had been read. By 1984 the basic Mailbox service had been extended to give automatic access to the
Telex The telex network is a station-to-station switched network of teleprinters similar to a telephone network, using telegraph-grade connecting circuits for two-way text-based messages. Telex was a major method of sending written messages electroni ...
service which at the time was still relatively common in business and was the standard way to reach remoter parts of the globe. Using a special ''Telex Link'' page, the message was composed in the usual way and then the destination country chosen and the Telex number entered before sending just like a standard message. Telex Link added the necessary Telex codes as required and tried to send the message as many times as required before positively confirming receipt by means of a special Mailbox message. Telexes could be sent to Prestel Mailbox users from a standard Telex terminal by using Telex Link number and inserting "MBX" and the relevant mailbox number as the first line of the telex message itself. The incoming telex message appeared to the Prestel recipient just as an ordinary Mailbox message but with the telex number inserted at the top of the frame. Because of the charges inherent in use of the Telex service, messages sent via Prestel Telex Link were chargeable, in 1984 at the rate of 50p for destinations in the UK, £1.00 for Europe, £2.00 for North America, £3.00 for elsewhere and even £5.00 for sending to ships via INMARSAT. There was no charge to Prestel users for receiving Telex messages. In the same year, when there were some 70,000 users registered, up to 100,000 mailboxes and telexes were sent each week via Prestel Mailbox. From July 1989, a new mailbox system was introduced Prestel Mailbox User Guide 1989 which allowed for single messages of up to five frames in length, storing of messages prior to sending, sending to multiple recipients, either individually or via a mailing list, forwarding of messages, and requesting an acknowledgment of receipt. Whilst sending a simple mailbox using none of the new facilities remained free, all of the new options were charged at 1p per use per recipient. For the first time, the sending of
spam Spam may refer to: * Spam (food), a canned pork meat product * Spamming, unsolicited or undesired electronic messages ** Email spam, unsolicited, undesired, or illegal email messages ** Messaging spam, spam targeting users of instant messaging ...
was accounted for and permitted, albeit at 20p per recipient. In addition, the stored message facility was replaced by a summary page, which listed all the messages, both new and old, that were waiting. The user could then pick which message to view, rather than being required to read through them all in chronological order. As only the first 20 could be accessed, this effectively allowed for up to 19 messages to be stored while allowing the continued reception of new mail. A security breach of the Prestel mailbox of the
Duke of Edinburgh Duke of Edinburgh, named after the city of Edinburgh in Scotland, was a substantive title that has been created three times since 1726 for members of the British royal family. It does not include any territorial landholdings and does not prod ...
and subsequent trial led to the
Computer Misuse Act 1990 The Computer Misuse Act 1990 is an Act of the Parliament of the United Kingdom, introduced partly in response to the decision in ''R v Gold & Schifreen'' (1988) 1 AC 1063 (see below). Critics of the bill complained that it was introduced hastily ...
.


Public take-up

While teletext services were provided free of charge, and were encoded as part of the regular television transmissions, Prestel data were transmitted via telephone lines to a set-top box terminal, computer, or dedicated terminal. While this enabled interactive services and a crude form of e-mail to be provided, gaining access to Prestel also involved purchasing a suitable terminal, and arranging with a Post Office engineer for the installation of a connection point known as a Jack 96A. (From the early 1980s, the "New Plan" sockets were fitted as standard on new lines and on any change of rented handset, and terminals or modems then required no special connections.) Thereafter it was necessary to pay both a monthly subscription and the cost of local telephone calls. On top of this, some services (notably parts of Micronet 800) sold content on a paid-for basis. Each Prestel screen carried a price in pence in the top right-hand corner. Single screens could cost up to 99p. The original idea was to persuade consumers to buy a modified television set with an inbuilt modem and a keypad remote control in order to access the service, but no more than a handful of models were ever marketed and they were prohibitively expensive. Eventually set-top boxes were made available, and some organisations made these available as part of their subscription, for example branded Tandata terminals were provided by the
Nottingham Building Society The Nottingham Building Society is a building society founded in 1849 by a group led by Samuel Fox (1781–1868), a Quaker and prominent local grocer. The purpose of the society was to promote the construction of a better class of dwellings, ...
for its customers, who could make
financial transactions A financial transaction is an agreement, or communication, between a buyer and seller to exchange goods, services, or assets for payment. Any transaction involves a change in the status of the finances of two or more businesses or individuals. A ...
via Prestel. Because the communication over telephone lines did not use any kind of error correction protocol, it was prone to interference from line noise which would result in garbled text. This was particularly problematic with early home modems which used
acoustic coupler In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone. The link is achieved through converting electric signals from the phone line to sound a ...
s, because most home phones were hard-wired to the wall at that time. Regardless of the hardware choice Prestel was an expensive proposition, and as a result, Prestel only ever gained a limited
market penetration Market penetration refers to the successful selling of a good or service in a specific market. It is measured by the amount of sales volume of an existing good or service compared to the total target market for that product or service. Market p ...
among private consumers, achieving a total of just 90,000 subscribers, with the largest user groups being Micronet 800 with 20,000 users and Prestel Travel with 6,500 subscribers. Micro Arts Group
computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great de ...
Software and Magazine had 400 pages and interactive art software to download. This prefigured mixed media websites on the Internet. It is the only organisation from this period still operating. The costs for businesses interested in publishing on Prestel were also expensive. This ensured that only the largest or most forward thinking companies were interested in the service. During the daytime, when business usage was high, there was a per-minute charge to use Prestel, but in the evenings and weekends, traditionally the quiet times, it was free apart from the telephone call. With Micronet being so popular, suddenly the quiet times became fairly busy. The BT Prestel software development team developed a number of national variants of Prestel, all of which ran on
GEC Computers GEC Computers Limited was a British computer manufacturing company under the GEC holding company from 1968 until the 1990s. History Starting life as Elliott Automation, in 1967–68 the data processing computer products were transferred to I ...
. They were sold to the PTTs of other countries, including Australia, Austria, Belgium, Italy, Hungary, Hong Kong, Germany, Netherlands, New Zealand, Singapore and Yugoslavia. Italy was the largest system with 180,000 subscribers. The Singapore system had a notable technology difference in that pages were not returned over the modem connection, but were returned using
teletext A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
methods over one of four television channels reserved specially for the purpose, which had all scan lines encoded in teletext format. This higher bandwidth enabled use of a feature called Picture Prestel which was used to carry significantly higher resolution pictures than were available on other Prestel systems. It was also demonstrated at the 1982 Worlds Fair in Knoxville, Tennessee. The original Prestel system, designed for cost effectiveness and simplicity, employed a rudimentary graphic capability known as serial mosaics. Through juxtaposition of the special mosaic characters, crude but recognizable graphic representations could be made on the screen. This graphic scheme had its limitations. To change colors between two mosaic graphic characters or between any two characters in general, a color change command was required. This command signal, however, physically occupied a blank space on the screen. The French sought to overcome this limitation when they joined the videotex world in the mid-1970s. They called their system Antiope. While based on the same mosaic graphics that were employed by the British, Antiope added a new feature, parallel attributes, or the ability to change the color from one cell to another without the need for a blank space. At approximately the same time, the Canadians adapted standard computer graphic commands into a set of functions called alphageometrics. These alphageometric functions did away with the block mosaic graphics used by the British and French and replaced them with drawing instructions, such as: DRAW LINE, DRAW ARC, DRAW POLYGON, etc. Through use of these geometric commands much higher resolution could be achieved than with the mosaic commands. This alphageometric scheme was integrated into the Canadian videotex system which the Canadians referred to as " Telidon". Having developed Prestel as a way of maximising usage of existing telephone lines, the British Post Office and subsequently British Telecom sought to "provide only the framework" for the service, delegating the provision of information to information providers. Nevertheless, considerable investment was required in the infrastructure to provide such a service. With information providers needing to pay rental charges and with users needing to pay installation and rental fees, such an investment was considered likely to pay off handsomely for BT and that they would be "cleaning up" by providing an interactive service that, in contrast to teletext services such as Ceefax and Oracle, could support a range of commercial activities. A "mass public service" was envisaged, with considerable public take-up, but a lack of compelling content and services gave domestic users in particular the impression of Prestel being something that "would cost them a lot for relatively little". Thus, Prestel became more like "a fragmented series of computer-linked private systems" used and run by various companies such as American Express and Thomas Cook, for whom adoption of the technology made sense operationally. Nevertheless, it was predicted that eventually, "Prestel - or another viewdata system - will be ubiquitous".


Successes

In contrast to the demise of the British system, the
French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...
equivalent of Prestel, Teletel/Minitel, received substantial public backing when millions of Minitel terminals were handed out free to telephone subscribers (causing Alcatel huge financial problems). As a consequence the Teletel network became very popular in France, and remained well used, with access later also possible over the Internet. After a short postponement, Minitel closed finally on 30 June 2012. In 1979 the New Opportunity Press launched Careerdata, an interactive graduate recruitment service devised and designed by Anthony Felix, the New Opportunity Press MD, and supported by GEC's Hirst Research centre in Wembley, London, who provided 12 terminals which were installed in the largest UK university careers advisory services. This was the first commercial application on the new medium and was featured in the Prestel Road Show which toured the UK and some European centres. A closed-access videotex system based on the Prestel model was developed by the travel industry, and continues to be almost universally used to this day by
travel agents A travel agency is a private retailer or public service that provides travel and tourism-related services to the general public on behalf of accommodation or travel suppliers to offer different kinds of travelling packages for each destinati ...
throughout the country: see Viewdata. The Prestel technology was also sold abroad to several countries, and in 1984 Prestel won a UK Queen's Award to Industry both for its innovative technology and use of British products (it largely ran on equipment provided by
GEC Computers GEC Computers Limited was a British computer manufacturing company under the GEC holding company from 1968 until the 1990s. History Starting life as Elliott Automation, in 1967–68 the data processing computer products were transferred to I ...
). In 1979
Michael Aldrich Michael Aldrich (22 August 1941 – 19 May 2014) was an English inventor, innovator and entrepreneur. In 1979 he invented online shopping to enable online transaction processing between consumers and businesses, or between one business and an ...
developed an
online shopping Online shopping is a form of electronic commerce which allows consumers to directly buy goods or services from a seller over the Internet using a web browser or a mobile app. Consumers find a product of interest by visiting the website of t ...
system, a type of
e-commerce E-commerce (electronic commerce) is the activity of electronically buying or selling of products on online services or over the Internet. E-commerce draws on technologies such as mobile commerce, electronic funds transfer, supply chain manag ...
, using a modified domestic
colour television Color television or Colour television is a television transmission technology that includes color information for the picture, so the video image can be displayed in color on the television set. It improves on the monochrome or black-and-white t ...
equipped with the Prestel chipset and connected to a real-time transaction-processing computer via a domestic dial-up telelphone line. During the 1980s he sold these online shopping systems to large corporations mainly in the UK. All the terminals on these systems could also access the Prestel systems. Aldrich installed a travel industry system in
Thomson Holidays Thomson Travel Group plc was a business formed by the Thomson Corporation of Canada, when it was floated on the London Stock Exchange in 1998. It was acquired by Preussag AG, an industrial and transport conglomerate, in 2000. The group contin ...
in 1981.Pioneers of Online Shopping, Aldrich Archive, University of Brighton www.aldricharchive.com


Other implementations

The Prestel system was customised and resold by
GEC Computers GEC Computers Limited was a British computer manufacturing company under the GEC holding company from 1968 until the 1990s. History Starting life as Elliott Automation, in 1967–68 the data processing computer products were transferred to I ...
to several other countries, including:
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
,
Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a List of cities in China, city and Special administrative regions of China, special ...
,
Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Cr ...
,
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
,
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federal constitutional monarchy consists of thirteen states and three federal territories, separated by the South China Sea into two regions: Peninsular Malaysia and Borneo's East Mal ...
,
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
,
Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...
and
Yugoslavia Yugoslavia (; sh-Latn-Cyrl, separator=" / ", Jugoslavija, Југославија ; sl, Jugoslavija ; mk, Југославија ;; rup, Iugoslavia; hu, Jugoszlávia; rue, label= Pannonian Rusyn, Югославия, translit=Juhoslavij ...
. Telecom Australia re-branded its system Viatel, with the centre of operations in
Windsor Windsor may refer to: Places Australia * Windsor, New South Wales ** Municipality of Windsor, a former local government area * Windsor, Queensland, a suburb of Brisbane, Queensland **Shire of Windsor, a former local government authority around Wi ...
,
Melbourne Melbourne ( ; Boonwurrung/ Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a metro ...
,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
. During the
Black Monday Black Monday refers to specific Mondays when undesirable or turbulent events have occurred. It has been used to designate massacres, military battles, and stock market crashes. Historic events *1209, Dublin – when a group of 500 recently arriv ...
stock market crash the system's stock trading system was highly used. The system in Italy run by SIP was heavily used during the
1990 FIFA World Cup The 1990 FIFA World Cup was the 14th FIFA World Cup, a quadrennial football tournament for men's senior national teams. It was held from 8 June to 8 July 1990 in Italy, the second country to host the event for a second time (the first being ...
for reporting the match progress and scores. The Singapore system provided a much higher receive bandwidth than was available over dial-up modems at the time by broadcasting the return frames using the
Teletext A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
technique of embedding them in broadcast television signals. Four
VHF Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF ...
TV channels were dedicated to this with all the
scan line A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube (CRT) display of a television set or computer monitor. On CRT screens the horizontal scan lines are visually discernible ...
s used for Teletext encoding, which enabled the system to provide a feature called ''Picture Prestel'' to convey higher resolution images. The Yugoslav system was based in
Zagreb Zagreb ( , , , ) is the capital (political), capital and List of cities and towns in Croatia#List of cities and towns, largest city of Croatia. It is in the Northern Croatia, northwest of the country, along the Sava river, at the southern slop ...
, with additional IRCs located in
Rijeka Rijeka ( , , ; also known as Fiume hu, Fiume, it, Fiume ; local Chakavian: ''Reka''; german: Sankt Veit am Flaum; sl, Reka) is the principal seaport and the third-largest city in Croatia (after Zagreb and Split). It is located in Prim ...
,
Ljubljana Ljubljana (also known by other historical names) is the capital and largest city of Slovenia. It is the country's cultural, educational, economic, political and administrative center. During antiquity, a Roman city called Emona stood in the ar ...
, and
Split Split(s) or The Split may refer to: Places * Split, Croatia, the largest coastal city in Croatia * Split Island, Canada, an island in the Hudson Bay * Split Island, Falkland Islands * Split Island, Fiji, better known as Hạfliua Arts, entertai ...
. The American
Viewtron Viewtron was an online service offered by Knight-Ridder and AT&T from 1983 to 1986. Patterned after the British Post Office's Prestel system, it started as a videotex service requiring users to have a special terminal, the AT&T Sceptre. As home ...
videotex service was modelled after Prestel.


Homelink

In 1983 the UK's first
online banking Online banking, also known as internet banking, web banking or home banking, is an electronic payment system that enables customers of a bank or other financial institution to conduct a range of financial transactions through the financial ins ...
service opened with
Homelink The HomeLink Wireless Control System is a radio frequency (RF) transmitter integrated into some automobiles that can be programmed to activate devices such as garage door openers, RF-controlled lighting, gates and locks, including those with rol ...
, which was a cooperation between the
Nottingham Building Society The Nottingham Building Society is a building society founded in 1849 by a group led by Samuel Fox (1781–1868), a Quaker and prominent local grocer. The purpose of the society was to promote the construction of a better class of dwellings, ...
and the
Bank of Scotland The Bank of Scotland plc (Scottish Gaelic: ''Banca na h-Alba'') is a commercial and clearing bank based in Scotland and is part of the Lloyds Banking Group, following the Bank of Scotland's implosion in 2008. The bank was established by th ...
.


See also

*
Compunet Compunet was a United Kingdom based interactive service provider, catering primarily for the Commodore 64 but later for the Commodore Amiga and Atari ST. It was also known by its users as ''CNet''. It ran from 1984 to May 1993. Overview Compune ...
*
Internet in the United Kingdom The United Kingdom has been involved with the Internet throughout its origins and development. The telecommunications infrastructure in the United Kingdom provides Internet access to businesses and home users in various forms, including fibre, ...
*
History of the World Wide Web The World Wide Web ("WWW", "W3" or, simply, "the Web") is a global information medium which users can access via computers connected to the Internet. The term is often mistakenly used as a synonym for the Internet, but the Web is a service tha ...
*
Minitel The Minitel was a videotex online service accessible through telephone lines, and was the world's most successful online service prior to the World Wide Web. It was invented in Cesson-Sévigné, near Rennes in Brittany, France. The service w ...
, a similar system developed in France. *
Bildschirmtext Bildschirmtext ( German "screen text", abbrev. Btx or BTX) was an online videotex system launched in West Germany in 1983 by the Deutsche Bundespost, the (West) German postal service. Btx originally required special hardware (it was based on ...
, a similar system developed in Germany. *
Singapore Teleview Singapore Teleview or known as Camp-Camp View or Ke Pik was a Singaporean videotext service. In the mid 1980s, the Telecom Authority of Singapore entered into a joint venture development with GEC Marconi in the UK to develop a photo-videotext pub ...
*
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
Colossus computer Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus ...
, also built by the Post Office Research Laboratories.


Notes


References

* * * * * * * * * * * * * Fedida, S. and Malik, R. (1979). The Viewdata Revolution. London, UK, Associated Business Press,


External links



Prestel Magazine. October 1983
Review
of Prestel from 1983 * Text and images from

given out at ''A Fanfare for Prestel'' event at Wembley in March 1980.

History of Prestel

Micro Arts Group 1984-2022
Celebrating the Viewdata Revolution
Including several Prestel Brochures {{Telecommunications BT Group History of telecommunications in the United Kingdom Legacy systems Pre–World Wide Web online services Videotex