NAPLPS (North American Presentation Level Protocol Syntax) is a
graphics language for use originally with
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 ...
and
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 ...
services. NAPLPS was developed from the
Telidon
Telidon (from the Greek words τῆλε, ''tele'' "at a distance" and ἰδών, ''idon'' "seeing") was a videotex/teletext service developed by the Canadian Communications Research Centre (CRC) during the late 1970s and supported by commercial ...
system developed in Canada, with a small number of additions from
AT&T Corporation
AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agen ...
. The basics of NAPLPS were later used as the basis for several other
microcomputer
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PC ...
-based graphics systems.
History
The Canadian
Communications Research Centre
The Communications Research Centre Canada (CRC; french: Centre de recherches sur les communications Canada) is a Canadian government scientific laboratory for research and development in wireless technologies, with a particular focus on the effic ...
(CRC), based in
Ottawa
Ottawa (, ; Canadian French: ) is the capital city of Canada. It is located at the confluence of the Ottawa River and the Rideau River in the southern portion of the province of Ontario. Ottawa borders Gatineau, Quebec, and forms the core ...
, had been working on various graphics systems since the late 1960s, much of it led by Herb Bown.
[Cynthia Boyko]
"Telidon"
Friends of the CRC, 14 October 1997 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
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
character. Graphic coordinates were encoded in multiple 6-bit strings of XY coordinate data, flagged to place them in the printable ASCII range so that they could be transmitted with conventional text transmission techniques.
ASCII SI/SO characters were used to differentiate the text from graphic portions of a transmitted "page". These instructions were decoded by separate programs to produce graphics output, on a
plotter
A plotter is a machine that produces vector graphics drawings. Plotters draw lines on paper using a pen, or in some applications, use a knife to cut a material like vinyl or leather. In the latter case, they are sometimes known as a cutting pl ...
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
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 ...
systems, notably the
BBC #REDIRECT BBC #REDIRECT BBC #REDIRECT BBC
Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board ex ...
's
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 ( ...
system. Ceefax encoded character data into the lines in the
vertical blanking interval
In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fram ...
of normal
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
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
The Independent Broadcasting Authority (IBA) was the regulatory body in the United Kingdom for commercial television (ITV and Channel 4 and limited satellite television regulation – cable television was the responsibility of the Cable Authorit ...
quickly introduced their own
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 '' ...
system, and the two organizations subsequently agreed to use a single standard, the "Broadcast Teletext Specification". This later became
World System Teletext
World System Teletext (WST) is the name of a standard for encoding and displaying teletext information, which is used as the standard for teletext throughout Europe today. It was adopted into the international standard ITU-R, CCIR 653 (now ITU-R BT ...
.
At about the same time, other organizations were developing
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 ...
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
The General Post Office (GPO) was the state postal system and telecommunications carrier of the United Kingdom until 1969. Before the Acts of Union 1707, it was the postal system of the Kingdom of England, established by Charles II in 1660. ...
developed a system using the Ceefax/ORACLE standard, launching it as
Prestel
Prestel (abbrev. from press telephone), the brand name for the UK Post Office Telecommunications's Viewdata technology, was an interactive videotex system developed during the late 1970s and commercially launched in 1979. It achieved a maximu ...
, while France prepared the first steps for its ultimately very successful
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 was ...
system, using a rival display standard called
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.
[
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
The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...
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
The Bell 202 modem was an early (1976) modem standard developed by the Bell System. It specifies audio frequency-shift keying (AFSK) to encode and transfer data at a rate of 1200 bits per second, half-duplex. It has separate sets of circuits fo ...
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
ASCII art is a graphic design technique that uses computers for presentation and consists of pictures pieced together from the 95 printable (from a total of 128) characters defined by the ASCII Standard from 1963 and ASCII compliant chara ...
s. The downside of the system was that it required much more advanced decoders, typically featuring Zilog Z80
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples wer ...
or Motorola 6809
The Motorola 6809 ("''sixty-eight-oh-nine''") is an 8-bit microprocessor with some 16-bit features. It was designed by Motorola's Terry Ritter and Joel Boney and introduced in 1978. Although source compatible with the earlier Motorola 6800, the 6 ...
processors with RGB and/or RF output. The Innovation, Science and Economic Development Canada
Innovation, Science and Economic Development Canada (ISED; french: Innovation, Sciences et Développement économique Canada; french: ISDE, label=none)''Innovation, Science and Economic Development Canada'' is the applied title under the Federal I ...
(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.[
]AT&T Corporation
AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agen ...
was so impressed by Telidon that they decided to join the project. 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 CSA
CSA may refer to:
Arts and media
* Canadian Screen Awards, annual awards given by the Academy of Canadian Cinema & Television
* Commission on Superhuman Activities, a fictional American government agency in Marvel Comics
* Crime Syndicate of Amer ...
/ANSI
The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...
working group (X3L2.1) revised the specifications, which were submitted for standardization. In 1983, they became CSA T500 and ANSI X3.110, or NAPLPS. The data encoding system was also standardized as the NABTS
NABTS, the North American Broadcast Teletext Specification, is a protocol used for encoding NAPLPS-encoded teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal. It is standard ...
(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
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
Telidon was being offered by companies who worked on a subscriber basis.
One-way systems
Telidon-based 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 ...
was tested in a few North American trials in the early 1980s — CBC IRIS, TVOntario
TVO Media Education Group (often abbreviated as TVO and stylized on-air as tvo) is a publicly funded English-language educational television network and media organization serving the Canadian province of Ontario. It is operated by the Ontario ...
, MTS-sponsored Project IDA, to name a few.
NAPLPS was also part of the NABTS
NABTS, the North American Broadcast Teletext Specification, is a protocol used for encoding NAPLPS-encoded teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal. It is standard ...
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
SportsChannel is the collective name for a former group of regional sports networks in the United States that was owned by Cablevision, which from 1988 until the group's demise, operated it as a joint venture with NBC.
Operating from March 1, 1 ...
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
Prodigy, Prodigies or The Prodigy may refer to:
* Child prodigy, a child who produces meaningful output to the level of an adult expert performer
** Chess prodigy, a child who can beat experienced adult players at chess
Arts, entertainment, and ...
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
Knight Ridder was an American media company, specializing in newspaper and Internet publishing. Until it was bought by McClatchy on June 27, 2006, it was the second largest newspaper publisher in the United States, with 32 daily newspaper brand ...
's 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 ...
(based in Miami
Miami ( ), officially the City of Miami, known as "the 305", "The Magic City", and "Gateway to the Americas", is a East Coast of the United States, coastal metropolis and the County seat, county seat of Miami-Dade County, Florida, Miami-Dade C ...
) and the ''Los Angeles Times
The ''Los Angeles Times'' (abbreviated as ''LA Times'') is a daily newspaper that started publishing in Los Angeles in 1881. Based in the LA-adjacent suburb of El Segundo since 2018, it is the sixth-largest newspaper by circulation in the Un ...
'' Gateway service (based in Orange County
Orange County most commonly refers to:
*Orange County, California, part of the Los Angeles metropolitan area
Orange County may also refer to:
U.S. counties
*Orange County, Florida, containing Orlando
*Orange County, Indiana
*Orange County, New ...
). Both used the Sceptre
A sceptre is a staff or wand held in the hand by a ruling monarch as an item of royal or imperial insignia. Figuratively, it means royal or imperial authority or sovereignty.
Antiquity
Ancient Egypt and Mesopotamia
The ''Was'' and other ...
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
Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
, Centel (since acquired by Sprint) and Field Enterprises
Field Enterprises, Inc. was a private holding company that operated from the 1940s to the 1980s, founded by Marshall Field III and others, whose main assets were the ''Chicago Sun'' and ''Parade'' magazine. For various periods of time, Field Enter ...
, then-owner of the ''Chicago Sun-Times
The ''Chicago Sun-Times'' is a daily newspaper published in Chicago, Illinois, United States. Since 2022, it is the flagship paper of Chicago Public Media, and has the second largest circulation among Chicago newspapers, after the ''Chicago T ...
'' newspaper. Keyfax had originally been a WST teletext service, broadcast overnights on Field's Chicago television station WFLD-32 and through the VBI of both WFLD and national superstation 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.
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
Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the List of cities in British Columbia, most populous city in the province, the 2021 Canadian census recorded 662,248 people in the ...
these were featured at Expo 86
The 1986 World Exposition on Transportation and Communication, or simply Expo 86, was a World's Fair held in Vancouver, British Columbia, Canada from May 2 until October 13, 1986. The fair, the theme of which was "Transportation and Communicatio ...
. The kiosks became ubiquitous in Toronto
Toronto ( ; or ) is the capital city of the Canadian province of Ontario. With a recorded population of 2,794,356 in 2021, it is the most populous city in Canada and the fourth most populous city in North America. The city is the ancho ...
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
Norpak Corporation was a company headquartered in Kanata, Ontario, Canada, that specialized in the development of systems for television-based data transmission. In 2010, it was acquired by Ross Video Ltd. of Iroquois and Ottawa, Ontario.
Norpa ...
, the most successful of NAPLPS-oriented developers. Norpak created and sold hardware and software for NAPLPS development and display. TVOntario
TVO Media Education Group (often abbreviated as TVO and stylized on-air as tvo) is a publicly funded English-language educational television network and media organization serving the Canadian province of Ontario. It is operated by the Ontario ...
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
Eaton Centre is a name associated with shopping centres in Canada, originating with Eaton's, one of Canada's largest department store chains at the time that these malls were developed. Eaton's partnered with development companies throughout ...
. 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
Tribune Content Agency (TCA) is a syndication company owned by Tribune Publishing. TCA had previously been known as the Chicago Tribune Syndicate, the Chicago Tribune New York News Syndicate (CTNYNS), Tribune Company Syndicate, and Tribune Media Se ...
(TMS) and the Associated Press
The Associated Press (AP) is an American non-profit news agency headquartered in New York City. Founded in 1846, it operates as a cooperative, unincorporated association. It produces news reports that are distributed to its members, U.S. newspa ...
operated a cable television channel called AP News Plus that provided NAPLPS-based news screens to cable television
Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broa ...
subscribers in many U.S. cities. The news pages were created and edited by TMS staffers working on an Atex
The ATEX directives are two EU directives describing the minimum safety requirements for workplaces and equipment used in explosive atmospheres. The name is an initialization of the French term ''Appareils destinés à être utilisés en ATmos ...
editing system in Orlando
Orlando () is a city in the U.S. state of Florida and is the county seat of Orange County. In Central Florida, it is the center of the Orlando metropolitan area, which had a population of 2,509,831, according to U.S. Census Bureau figures rele ...
, Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
, 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
Minneapolis () is the largest city in Minnesota, United States, and the county seat of Hennepin County. The city is abundant in water, with thirteen lakes, wetlands, the Mississippi River, creeks and waterfalls. Minneapolis has its origins ...
-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
Bell Canada (commonly referred to as Bell) is a Canadian telecommunications company headquartered at 1 Carrefour Alexander-Graham-Bell in the borough of Verdun in Montreal, Quebec, Canada. It is an ILEC (incumbent local exchange carrier) in t ...
offered a dial-up
Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telepho ...
Telidon service called Alex
Alex is a given name. It can refer to a shortened version of Alexander, Alexandra, Alexis.
People
Multiple
*Alex Brown (disambiguation), multiple people
* Alex Gordon (disambiguation), multiple people
*Alex Harris (disambiguation), multiple pe ...
, similar in spirit to the French 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 was ...
, with the telephone directory its principal information offering.
Decline
NAPLPS lived on into the early 1990s as the graphical basis for the Prodigy
Prodigy, Prodigies or The Prodigy may refer to:
* Child prodigy, a child who produces meaningful output to the level of an adult expert performer
** Chess prodigy, a child who can beat experienced adult players at chess
Arts, entertainment, and ...
online service. Some bulletin board
A bulletin board (pinboard, pin board, noticeboard, or notice board in British English) is a surface intended for the posting of public messages, for example, to advertise items wanted or for sale, announce events, or provide information. B ...
s were able to serve NAPLPS content to callers on their 1200 and 2400 bit/s 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 Modulation#Digital modulati ...
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
upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ...
compression became popular.
Legacy
In the 1980s, the Graphical Kernel System
The Graphical Kernel System (GKS) was the first ISO standard for low-level computer graphics, introduced in 1977. A draft international standard was circulated for review in September 1983.
Final ratification of the standard was achieved in 1985. ...
(GKS) library
A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vir ...
, 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
Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser DOS, DOS Plus, DR DOS and ...
's GSX graphics system used in their GEM
A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, a ...
GUI
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
. GKS was later extended into a 3D version, and additions to this resulted in PHIGS
PHIGS (Programmer's Hierarchical Interactive Graphics System) is an application programming interface (API) standard for rendering 3D computer graphics, considered to be the 3D graphics standard for the 1980s through the early 1990s. Subsequently, ...
(Programmer's Hierarchical Interactive Graphics System), a competitor to OpenGL
OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardwa ...
.
See also
* Remote Imaging Protocol
The Remote Imaging Protocol and its associated Remote Imaging Protocol Script language, RIP''scrip'', is a graphics language that provides a system for sending vector graphics over low-bandwidth links, notably modems. It was originally created b ...
(a.k.a. RIPscrip)
References
External links
NAPLPS
Michael Dillon's description of the format
IEEE Canada
IEEE Canada
* ttps://web.archive.org/web/20070310235336/http://www.telidonhistoryproject.ca/ The Telidon History Projectbr>ONE BBSCON 1993: NAPLPS: Universal Graphics for BBSs to the Internet, presented by Dave Hughes (August 27, 1993)
"NAPLPS"
user-created documentation of the NAPLPS standard
"Television Broadcast Videotex"
Industry Canada, BS-14 (Issue 1, Provisional), 19 June 1981 - NABTS standard
Videotex/Teletext Presentation Level Protocol Syntax
CSA T500-1983/ANSI X3.110-1983 standard (FIPS Pub 121)
PCWorld slide show of Prodigy graphic screens (Feb 18, 2016, archived)
{{DEFAULTSORT:Naplps
Computer graphics
Teletext
Videotex
Presentation layer protocols