Engineering:Viewdata: Difference between revisions

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'''Viewdata''' is a [[Videotex]] implementation.  It is a type of [[Information retrieval|information retrieval]] service in which a subscriber can [[Access control|access]] a remote [[Database|database]] via a [[Common carrier|common carrier]] [[Engineering:Communication channel|channel]], request [[Data|data]] and receive requested data on a [[Engineering:Video|video]] display over a separate channel. Samuel Fedida, who had the idea for Viewdata in 1968, was credited as inventor of the system which was developed while working for the British Post Office which was the operator of the national telephone system. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels.  This is in contrast with teletext.
'''Viewdata''' is a [[Videotex]] implementation.  It is a type of [[Information retrieval|information retrieval]] service in which a subscriber can [[Access control|access]] a remote [[Database|database]] via a [[Common carrier|common carrier]] [[Communication channel|channel]], request [[Data|data]] and receive requested data on a [[Engineering:Video|video]] display over a separate channel. Samuel Fedida, who had the idea for Viewdata in 1968, was credited as inventor of the system which was developed while working for the British Post Office which was the operator of the national telephone system. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels.  This is in contrast with teletext.


== Design ==
== Design ==
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Viewdata offered a display of 40×24 characters, based on ISO 646 (IRV IA5) – 7 bits with no accented characters.<ref name=aei>{{cite web| url=http://aei.pitt.edu/94572/1/videotex.pdf | title=Proceedings of the Videotex in Europe | access-date=2023-12-26 | date=1979-07-19}}</ref>
Viewdata offered a display of 40×24 characters, based on ISO 646 (IRV IA5) – 7 bits with no accented characters.<ref name=aei>{{cite web| url=http://aei.pitt.edu/94572/1/videotex.pdf | title=Proceedings of the Videotex in Europe | access-date=2023-12-26 | date=1979-07-19}}</ref>
Originally, Viewdata was accessed with a special purpose [[Computer terminal|terminal]] (or [[Emulator|emulation software]]) and a [[Modem|modem]] running at ITU-T V.23 speed (1,200 bit/s down, 75 bit/s up).<ref name=aei/> By 2004, it was normally accessed over TCP/IP using Viewdata client software on a [[Engineering:Personal computer|personal computer]] running [[Software:Microsoft Windows|Microsoft Windows]], or using a Web-based emulator.
Originally, Viewdata was accessed with a special purpose [[Computer terminal|terminal]] (or [[Emulator|emulation software]]) and a [[Modem|modem]] running at ITU-T V.23 speed (1,200 bit/s down, 75 bit/s up).<ref name=aei/> By 2004, it was normally accessed over TCP/IP using Viewdata client software on a [[Engineering:Personal computer|personal computer]] running [[Software:Microsoft Windows|Microsoft Windows]], or using a Web-based emulator.
===Keypad symbols: the sextile and the square===


{{Infobox symbol
{{Infobox symbol
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[[File:AVAYA 9611G IP Phone detail of star and hash.jpg |thumb|left|Detail of a more recent telephone keypad, in which (typographic) asterisk and number{{nbsp}}sign have replaced the ITU star and square]]
[[File:AVAYA 9611G IP Phone detail of star and hash.jpg |thumb|left|Detail of a more recent telephone keypad, in which (typographic) asterisk and number{{nbsp}}sign have replaced the ITU star and square]]


Viewdata uses special symbols already widely available on telephone keypads: the {{key press|⚹}} "star" key and the {{key press|⌗}} "square" key, as formally standardised by the [[Organization:International Telecommunication Union|International Telecommunication Union]].<ref>{{cite web | url =  http://www.itu.int/rec/T-REC-E.161-200102-I/en | title = E.161 : Arrangement of digits, letters and symbols on telephones and other devices that can be used for gaining access to a telephone network | publisher = [[Organization:International Telecommunication Union|International Telecommunication Union]] | date= 2 February 2001 | access-date =  23 December 2019}}</ref> These are often treated as approximately corresponding to the ASCII asterisk (*) and number sign (#), which do not necessarily conform to the ITU specifications for the keypad symbols; the asterisk is also usually displayed smaller and raised.<ref name="L213105r" />
Viewdata uses special symbols already widely available on telephone keypads: the {{key press|⚹}} "[[Engineering:Telephone keypad#Star key|star key]]" and the {{key press|⌗}} "[[Engineering:Telephone keypad#Square key|square key]]", as formally recommended by the [[Organization:International Telecommunication Union|International Telecommunication Union]].<ref>{{cite web | url =  http://www.itu.int/rec/T-REC-E.161-200102-I/en | title = E.161 : Arrangement of digits, letters and symbols on telephones and other devices that can be used for gaining access to a telephone network | publisher = [[Organization:International Telecommunication Union|International Telecommunication Union]] | date= 2 February 2001 | access-date =  23 December 2019}}</ref> The ASCII asterisk (*) and number sign (#) are sometimes used instead because they are regular symbols on [[Computer keyboard|computer keyboard]]s, although they do not match the ITU specification.<ref name="L213105r" /> On telephones, use of the number sign (hash symbol) has become the norm rather than the exception


These symbols appear as 'Sextile' and 'Viewdata square' in the [[Miscellaneous Symbols]] and [[Miscellaneous Technical]] Unicode blocks, respectively. The sextile was added due to [[Unsolved:Astrological aspect|its use in astrology]],<ref name="L213105r">{{cite web|url=https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-date=2022-10-09 |url-status=live | title= Proposal to incorporate two telephony symbols into Unicode by glyph and annotation changes | date= 28 October 2013 | access-date =  23 December 2019 | author = Karl Pentzlin |id=UTC L2/13-105R}}</ref> and the square had previously appeared in the BS Viewdata character set, as a replacement for the underscore.<ref name="ISO-IR-047">{{cite iso-ir |title=Alphanumerics for viewdata and broadcast teletext |sponsor=BSI |sponsor-link=BSI Group |date=1981-06-01 |number=47}}</ref>
These symbols appear as {{unichar2|⚹}} and {{unichar2|⌗|nlink=}} in the [[Miscellaneous Symbols]] and [[Miscellaneous Technical]] Unicode blocks, respectively. The sextile was added due to [[Unsolved:Astrological aspect|its use in astrology]],<ref name="L213105r">{{cite web|url=https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://unicode.org/L2/L2013/13105r-telephony.pdf |archive-date=2022-10-09 |url-status=live | title= Proposal to incorporate two telephony symbols into Unicode by glyph and annotation changes | date= 28 October 2013 | access-date =  23 December 2019 | author = Karl Pentzlin |id=UTC L2/13-105R}}</ref> and the square had previously appeared in the BS Viewdata character set, as a replacement for the underscore.<ref name="ISO-IR-047">{{cite iso-ir |title=Alphanumerics for viewdata and broadcast teletext |sponsor=BSI |sponsor-link=BSI Group |date=1981-06-01 |number=47}}</ref>


In 2013, the German national body submitted a [[Organization:Unicode Consortium|Unicode Technical Committee]] proposal to align the Unicode reference glyphs with the ITU specifications for these symbols, and annotate them as telephone keypad symbols on the code charts.<ref name="L213105r" /> {{as of|2019}} (Unicode 12.1), these changes have not been accepted/implemented.<ref>{{cite web |url=https://www.unicode.org/charts/PDF/U2300.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.unicode.org/charts/PDF/U2300.pdf |archive-date=2022-10-09 |url-status=live |title=Miscellaneous Technical |work=The Unicode Standard |author=Unicode Consortium |}}</ref>
In 2013, the German national body submitted a [[Organization:Unicode Consortium|Unicode Technical Committee]] proposal to align the Unicode reference glyphs with the ITU specifications for these symbols, and annotate them as telephone keypad symbols on the code charts.<ref name="L213105r" /> {{as of|2019}} (Unicode 12.1), these changes have not been accepted/implemented.<ref>{{cite web |url=https://www.unicode.org/charts/PDF/U2300.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.unicode.org/charts/PDF/U2300.pdf |archive-date=2022-10-09 |url-status=live |title=Miscellaneous Technical |work=The Unicode Standard |author=Unicode Consortium |}}</ref>
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=== Travel industry ===
=== Travel industry ===
As of 2015, Viewdata was still in use in the United Kingdom, mainly by the travel industry. Travel agents use it to look up the price and availability of package holidays and flights. Once they find what the customer is looking for they can place a booking.
As of 2015, Viewdata was still in use in the United Kingdom, mainly by the travel industry. Travel agents use it to look up the price and availability of package holidays and flights. Once they find what the customer is looking for they can place a booking. As of 2019, Viewdata is only used by a handful of travel agents.<ref>{{Cite web |title=Agents vote for return of Viewdata in online poll |url=https://travelweekly.co.uk/news/agents-vote-for-return-of-viewdata-in-online-poll |access-date=2025-12-03 |website=Travel Weekly |language=En}}</ref>
 
There are a number of factors still holding up a move to a [[World Wide Web|Web]]-based standard. Viewdata is regarded within the industry as low-cost and reliable, travel consultants have been trained to use Viewdata and would need training to book holidays on the Internet, and tour operators cannot agree on a Web-based standard.


=== Bulletin board systems ===
=== Bulletin board systems ===

Latest revision as of 12:07, 6 April 2026

Viewdata is a Videotex implementation. It is a type of information retrieval service in which a subscriber can access a remote database via a common carrier channel, request data and receive requested data on a video display over a separate channel. Samuel Fedida, who had the idea for Viewdata in 1968, was credited as inventor of the system which was developed while working for the British Post Office which was the operator of the national telephone system. The first prototype became operational in 1974. The access, request and reception are usually via common carrier broadcast channels. This is in contrast with teletext.

Design

Viewdata offered a display of 40×24 characters, based on ISO 646 (IRV IA5) – 7 bits with no accented characters.[1] Originally, Viewdata was accessed with a special purpose terminal (or emulation software) and a modem running at ITU-T V.23 speed (1,200 bit/s down, 75 bit/s up).[1] By 2004, it was normally accessed over TCP/IP using Viewdata client software on a personal computer running Microsoft Windows, or using a Web-based emulator.

Keypad symbols: the sextile and the square

⌗ ⚹
Viewdata keypad symbols
In UnicodeU+2317 ⌗ (HTML &#8983;)
U+26B9 ⚹ [[|]] (HTML &#9913;)
Different from
Different fromU+002A * [[|]] (HTML &#42;)
U+0023 # [[|]] (HTML &#35;)
Detail of a telephone keypad displaying the sextile and Viewdata square
Detail of a more recent telephone keypad, in which (typographic) asterisk and number sign have replaced the ITU star and square

Viewdata uses special symbols already widely available on telephone keypads: the "star key" and the "square key", as formally recommended by the International Telecommunication Union.[2] The ASCII asterisk (*) and number sign (#) are sometimes used instead because they are regular symbols on computer keyboards, although they do not match the ITU specification.[3] On telephones, use of the number sign (hash symbol) has become the norm rather than the exception

These symbols appear as Template:Unichar2 and Template:Unichar2 in the Miscellaneous Symbols and Miscellaneous Technical Unicode blocks, respectively. The sextile was added due to its use in astrology,[3] and the square had previously appeared in the BS Viewdata character set, as a replacement for the underscore.[4]

In 2013, the German national body submitted a Unicode Technical Committee proposal to align the Unicode reference glyphs with the ITU specifications for these symbols, and annotate them as telephone keypad symbols on the code charts.[3] As of 2019 (Unicode 12.1), these changes have not been accepted/implemented.[5]

Uses

Travel industry

As of 2015, Viewdata was still in use in the United Kingdom, mainly by the travel industry. Travel agents use it to look up the price and availability of package holidays and flights. Once they find what the customer is looking for they can place a booking. As of 2019, Viewdata is only used by a handful of travel agents.[6]

Bulletin board systems

A number of Viewdata bulletin board systems existed in the 1980s, predominantly in the UK due to the proliferation of the BBC Micro, and a short-lived Viewdata Revival appeared in the late 1990s fuelled by the retrocomputing vogue. Some Viewdata boards still exist, with accessibility in the form of Java Telnet clients.

See also

  • Prestel

References

  1. ↑ 1.0 1.1 "Proceedings of the Videotex in Europe". 1979-07-19. http://aei.pitt.edu/94572/1/videotex.pdf. 
  2. ↑ "E.161 : Arrangement of digits, letters and symbols on telephones and other devices that can be used for gaining access to a telephone network". International Telecommunication Union. 2 February 2001. http://www.itu.int/rec/T-REC-E.161-200102-I/en. 
  3. ↑ 3.0 3.1 3.2 Karl Pentzlin (28 October 2013). "Proposal to incorporate two telephony symbols into Unicode by glyph and annotation changes". https://unicode.org/L2/L2013/13105r-telephony.pdf. 
  4. ↑ BSI (1981-06-01), Alphanumerics for viewdata and broadcast teletext, ITSCJ/IPSJ, ISO-IR-47, https://www.itscj.ipsj.or.jp/iso-ir/047.pdf 
  5. ↑ Unicode Consortium. "Miscellaneous Technical". The Unicode Standard. https://www.unicode.org/charts/PDF/U2300.pdf. 
  6. ↑ "Agents vote for return of Viewdata in online poll" (in En). https://travelweekly.co.uk/news/agents-vote-for-return-of-viewdata-in-online-poll. 

Template:Videotex



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