View source for NAPLPS

{{Short description|Graphics language for videotex and teletext services}}

{{Use mdy dates|date=March 2025}}

'''NAPLPS''' ('''North''' '''American''' '''Presentation''' '''Layer''' '''Protocol''' '''Syntax''') is a [[Vector graphics markup language|graphics language]] for use originally with [[videotex]] and [[teletext]] services. NAPLPS was developed from the [[Telidon]] system developed in Canada, with a small number of additions from [[AT&T Corporation]]. The basics of NAPLPS were later used as the basis for several other [[Micro Computer Machines|microcomputer]]-based graphics systems.

== History ==
<!-- Deleted image removed: [[Image:Viewtron testing area.jpg|thumb|left|NAPLPS graphics on [[Viewtron]]]] -->

The Canadian [[Communications Research Centre]] (CRC), based in [[Ottawa]], had been working on various graphics systems since the late 1960s, much of it led by Herb Bown.<ref name="crc">{{Cite web |last=Boyko |first=Cynthia |date=August 8, 1996 |title=Telidon |url=https://www.friendsofcrc.ca/Projects/Telidon/Telidon.html |access-date=2025-03-21 |website=Friends of the CRC}}</ref> Through the 1970s they turned their attention to building out a system of "picture description instructions", which encoded graphics commands as a text stream.

Graphics were encoded as a series of instructions (graphics primitives) each represented by a single [[ASCII]] character. Graphic coordinates were encoded in multiple 6-bit strings of XY coordinate data, flagged to place them in the printable ASCII range so that they could be transmitted with conventional text transmission techniques. [[Shift Out and Shift In characters|ASCII SI/SO]] characters were used to differentiate the text from graphic portions of a transmitted "page". These instructions were decoded by separate programs to produce graphics output, on a [[plotter]] for instance. Other work produced a fully interactive version. In 1975, the CRC gave a contract to [[Norpak]] to develop an interactive graphics terminal that could decode the instructions and display them on a color display.

During this period, a number of companies were developing the first [[teletext]] systems, notably the [[BBC]]'s [[Ceefax]] system. Ceefax encoded character data into the lines in the [[vertical blanking interval]]  of normal [[television]] signals where they could not be seen on-screen, and then used a buffer and decoder in the user's television to convert these into "pages" of text on the display. The [[Independent Broadcasting Authority]] quickly introduced their own [[ORACLE (teletext)|ORACLE]] system, and the two organizations subsequently agreed to use a single standard, the "Broadcast Teletext Specification". This later became [[World System Teletext]].

At about the same time, other organizations were developing [[videotex]] systems, similar to teletext except they used modems to transmit their data instead of television signals. This was potentially slower and used up a telephone line, but had the major advantage of allowing the user to transmit data back to the sender.  The UK's [[General Post Office]] developed a system using the Ceefax/ORACLE standard, launching it as [[Prestel]], while France prepared the first steps for its ultimately very successful [[Minitel]] system, using a rival display standard called [[Antiope (teletext)|Antiope]].

By 1977, the Norpak system was running, and from this work the CRC decided to create their own teletext/videotext system. Unlike the systems being rolled out in Europe, the CRC decided from the start that the system should be able to run on any combination of communications links. For instance, it could use the vertical blanking interval to send data to the user, and a modem to return selections to the servers. It could be used in a one-way or two-way system.<ref name=crc/>

In teletext mode, character codes were sent to users' televisions by encoding them as dot patterns in the vertical blanking interval of the video signal. Various technical "tweaks" and details of the [[NTSC]] signals used by North American televisions allowed the downstream videotex channel to increase to 600 bit/s, about twice that used in the European systems. In videotext mode, [[Bell 202]] modems were typical, offering a 1,200 bit/s download rate. A set top box attached to the TV decoded these signals back into text and graphics pages, which the user could select among. 

The system was publicly launched as '''Telidon''' on August 15, 1978. Compared to the European standards, the CRC system was faster, bi-directional, and offered real graphics as opposed to simple [[character graphic]]s. The downside of the system was that it required much more advanced decoders, typically featuring [[Zilog Z80]] or [[Motorola 6809]] processors with RGB and/or RF output. The [[Innovation, Science and Economic Development Canada]] (then Department of Communications) launched a four-year plan to fund public roll-outs of the technology in an effort to spur the development of a commercial Telidon system.<ref name=crc/>

[[AT&T Corporation]] was so impressed by Telidon that they decided to join the project.{{citation needed|date=August 2021}} They added a number of useful extensions, notably the ability to define original graphics commands (''macro'') and character sets (''DRCS''). They also tabled algorithms for proportionally spaced text, which greatly improved the quality of the displayed pages. A joint [[Canadian Standards Association|CSA]]/[[American National Standards Institute|ANSI]] working group (X3L2.1) revised the specifications, which were submitted for standardization. In 1983, they became CSA T500 and ANSI X3.110, or NAPLPS.<ref>{{Cite book |last=Dixon |first=Douglas F. |title=Proceedings of the 10th annual conference on Computer graphics and interactive techniques - SIGGRAPH '83 |chapter=A Core Graphics Environment for Teletext Simulations |year=1983 |pages=175–181 |doi=10.1145/800059.801148 |isbn=0897911091 |s2cid=2774740 |chapter-url=https://dl.acm.org/doi/pdf/10.1145/800059.801148}}</ref> The data encoding system was also standardized as the [[NABTS]] (North American Broadcast Teletext Specification) protocol.

Business models for Telidon services were poorly developed. Unlike the UK, where teletext was supported by one of only two large companies whose whole revenue model was based on a read-only medium (television), in [[North America]] Telidon was being offered by companies who worked on a subscriber basis.

== One-way systems ==

Telidon-based [[teletext]] was tested in a few North American trials in the early 1980s &mdash; [[Canadian Broadcasting Corporation|CBC]] IRIS, [[TVOntario]], [[Manitoba Telecom Services|MTS]]-sponsored [[Project IDA]], to name a few.

NAPLPS was also part of the [[NABTS]] teletext standard, for the encoding and display of teletext pages.

In the late 1980s and early 1990s, affiliates of the regional sports network group [[SportsChannel]] ran a service called [[Sports Plus Network]], which ran sports news and scores while SportsChannel was not otherwise on the air. The screens, which frequently featured team logos or likenesses of players in addition to text, were drawn entirely with NAPLPS graphics and resembled the loading of [[Prodigy (online service)|Prodigy]] pages over a modem, though slightly faster.

== Two-way systems ==

Various two-way systems using NAPLPS appeared in North America in the early 1980s. The biggest North American examples were [[Knight Ridder]]'s [[Viewtron]] (based in [[Miami]]) and the ''[[Los Angeles Times]]''{{'}} [[Gateway (online service)|Gateway]] service (based in [[Orange County, California|Orange County]]). Both used the [[AT&T Sceptre|Sceptre]] NAPLPS terminal from AT&T. The Sceptre contained a slow modem that connected over the consumer's telephone line to host computers. The Sceptre was expensive whether purchased or rented. Despite huge investments by their parent companies, neither Viewtron nor Gateway lasted into the second half of the decade. Another system, Keyfax, was developed by Keycom Electronic Publishing, a joint venture of [[Honeywell]], Centel (since acquired by Sprint) and [[Field Enterprises]], then-owner of the ''[[Chicago Sun-Times]]'' newspaper. Keyfax had originally been a WST teletext service, broadcast overnights on Field's Chicago television station [[WFLD|WFLD-32]]<ref>{{Citation |title=WFLD Channel 32 - Nite-Owl (Complete & Remastered, 8/25/1982) 🦉 |url=https://www.youtube.com/watch?v=Bgs0kbxo68w |language=en |access-date=2022-11-21}}</ref> and through the VBI of both WFLD and national superstation [[WTBS (TV)|WTBS]]; the decision was made to convert Keyfax into a subscription service, using a proprietary NAPLPS terminal device in a last-ditch effort to save the service. It did not work and Keyfax had ceased operations by the end of 1986.<ref>{{Cite web |title=Keycom |url=https://iml.jou.ufl.edu/carlson/history/Keycom.htm |access-date=2022-11-21 |website=iml.jou.ufl.edu}}</ref>

Other early-1980s NAPLPS technology was deployed in Canada, both as a way for rural Canadians to get news and weather information and as the platform for touchscreen information kiosks. In [[Vancouver]] these were featured at [[Expo 86]].  The kiosks became ubiquitous in [[Toronto]] under the name ''Teleguide,'' and were deployed in many shopping centres and at major tourist attractions. The latter city was the North American nexus of NAPLPS and the home of [[Norpak]], the most successful of NAPLPS-oriented developers. Norpak created and sold hardware and software for NAPLPS development and display. [[TVOntario]] also developed NAPLPS content creation software.

London, Ontario - based Cableshare used NAPLPS as the basis of touch-screen information kiosks for shopping malls, the flagship of which was deployed at Toronto's [[Eaton Centre]]. The system relied on an 8085-based microcomputer which drove several NAPLPS terminals fitted with touch screens, all communicating via [[Datapac]] to a back end database. The system offered news, weather and sports information along with shopping mall guides and coupons. Cableshare also developed and sold a leading NAPLPS page creation utility called the "Picture Painter."

In the late 1980s, [[Tribune Media Services]] (TMS) and the [[Associated Press]] operated a cable television channel called AP News Plus that provided NAPLPS-based news screens to [[cable television]] subscribers in many U.S. cities. The news pages were created and edited by TMS staffers working on an [[Atex (software)|Atex]] editing system in [[Orlando, Florida|Orlando]], [[Florida]], and sent by satellite to NAPLPS decoder devices located at the local cable television companies. Among the firms providing technology to TMS and the Associated Press for the AP News Plus channel was [[Minneapolis]]-based Electronic Publishers Inc. (1985–1988).

In 1981, two amateur radio operators (VE3FTT and VE3GQW) received special permission from the Canadian Department of Communications to carry out on-air experiments using NAPLPS syntax which was technically not legal at the time because it was a "coded transmission".  Following their report on the success of the tests, the DOC then permitted general use of NAPLPS on amateur radioteletype.  This was reported in the ARRL Radio Handbook for several years following.

Between 1988 and 1994, [[Bell Canada]] offered a [[Modem|dial-up]] Telidon service called [[Alex (videotex service)|Alex]],<ref>{{Cite web |title=american teletext - ריהוט משרדי |url=http://www.office-furniture.org.il/lcvank9o/ |access-date=2022-12-09 |website=www.office-furniture.org.il |language=he-IL}}</ref> similar in spirit to the French [[Minitel]], with the telephone directory its principal information offering.

== Decline ==
NAPLPS lived on into the early 1990s as the graphical basis for the [[Prodigy (online service)|Prodigy]] online service. Some [[bulletin board system|bulletin board]]s were able to serve NAPLPS content to callers on their 1200 and 2400 bit/s [[modem]]s. But the technology's chief advantage in an era of slow telecommunication - its ability to encode complex graphics in terse object commands - became moot as data communication speeds increased and [[raster graphics]] compression became popular.

== Legacy ==
In the 1980s, the [[Graphical Kernel System]] (GKS) [[Library (computing)|library]], based on a 1970s specification with a similar basic geometry and command structure to NAPLPS, was widely implemented on microcomputers, and became the basis of [[Digital Research]]'s [[Graphics System Extension|GSX]] graphics system used in their [[GEM (desktop environment)|GEM]] [[Graphical user interface|GUI]]. GKS was later extended into a 3D version, and additions to this resulted in [[PHIGS]] (Programmer's Hierarchical Interactive Graphics System), a competitor to [[OpenGL]].

== See also ==
* [[Remote Imaging Protocol]] (a.k.a. RIPscrip)
* {{slink|Videotex character set|Data Syntax 3}}

== References ==
<references/>

== External links ==
*[https://www.martinreddy.net/gfx/2d/NAP.txt NAPLPS], Michael Dillon's description of the format
*[https://ewh.ieee.org/reg/7/millennium/telidon/telidon_about.html Telidon Introduction], IEEE Canada
*[https://www.ewh.ieee.org/reg/7/millennium/telidon/telidon_twoway.html IEEE Canada's Telidon: Two-way TV is Here], IEEE Canada
*[https://web.archive.org/web/20150524162134/http://www.wlu.ca/~wwwpress/jrls/cjc/BackIssues/16.2/devon.html Canadian Journal of Communications: Interactivity and the Popular Support for Telidon]
*[https://web.archive.org/web/20070310235336/http://www.telidonhistoryproject.ca/ The Telidon History Project]
*[https://archive.org/details/93bbscon-naplps ONE BBSCON 1993: NAPLPS: Universal Graphics for BBSs to the Internet, presented by Dave Hughes (August 27, 1993)]
* [https://www.martinreddy.net/gfx/2d/NAP.txt "NAPLPS"], user-created documentation of the NAPLPS standard
* [https://www.ic.gc.ca/eic/site/smt-gst.nsf/vwapj/bs14.pdf/$FILE/bs14.pdf "Television Broadcast Videotex"], Industry Canada, BS-14 (Issue 1, Provisional), 19 June 1981 - NABTS standard
* [https://archive.org/details/federalinformati121nati Videotex/Teletext Presentation Level Protocol Syntax ], CSA T500-1983/ANSI X3.110-1983 standard (FIPS Pub 121)
*[https://web.archive.org/web/20160308114238/http://www.pcworld.com/article/3034592/internet/this-old-tech-exploring-the-lost-world-of-prodigy-one-screen-at-a-time.html#slide1 This Old Tech: Exploring the lost world of Prodigy], PCWorld slide show of Prodigy graphic screens (Feb 18, 2016, archived)

{{Videotex}}
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[[Category:Computer graphics]]
[[Category:Teletext]]
[[Category:Videotex]]
[[Category:Presentation layer protocols]]