Internet access is a facility or service that provides connectivity for a computer, a computer network, or other network device to the Internet , and for individuals or organizations to access or use applications such as email and the World Wide Web . Internet access is offered for sale by an international hierarchy of Internet service providers (ISPs) using various networking technologies. At the retail level, many organizations, including municipal entities, also provide cost-free access to the general public.
107-514: BT Broadband is a broadband service offered by BT Consumer ; a division of BT Group in the United Kingdom . It was formerly known as BT Total Broadband, BT Yahoo! Broadband and BT Openworld. With the introduction of BT Infinity, the Broadband package now refers to the legacy ADSL broadband products, such as ADSL Max and ADSL2+ . The BT Home Hub is a wireless Internet router from BT . It
214-427: A cable modem on hybrid fiber coaxial (HFC) wiring originally developed to carry television signals. Either fiber-optic or coaxial copper cable may connect a node to a customer's location at a connection known as a cable drop. Using a cable modem termination system , all nodes for cable subscribers in a neighborhood connect to a cable company's central office, known as the "head end." The cable company then connects to
321-401: A computer or a computing system. Most early computers only had a front panel to input or display bits and had to be connected to a terminal to print or input text through a keyboard. Teleprinters were used as early-day hard-copy terminals and predated the use of a computer screen by decades. The computer would typically transmit a line of data which would be printed on paper, and accept
428-494: A laptop or PDA . These services may be free to all, free to customers only, or fee-based. A Wi-Fi hotspot need not be limited to a confined location since multiple ones combined can cover a whole campus or park, or even an entire city can be enabled. Additionally, mobile broadband access allows smartphones and other digital devices to connect to the Internet from any location from which a mobile phone call can be made, subject to
535-453: A 128 kbit/s service. Multiple ISDN-BRI lines can be bonded together to provide data rates above 128 kbit/s. Primary rate ISDN, known as ISDN-PRI, has 23 bearer channels (64 kbit/s each) for a combined data rate of 1.5 Mbit/s (US standard). An ISDN E1 (European standard) line has 30 bearer channels and a combined data rate of 1.9 Mbit/s. ISDN has been replaced by DSL technology, and it required special telephone switches at
642-544: A DS0 to provide data rates between 56 and 1500 kbit/s . T-carrier lines require special termination equipment such as Data service units that may be separate from or integrated into a router or switch and which may be purchased or leased from an ISP. In Japan the equivalent standard is J1/J3. In Europe, a slightly different standard, E-carrier , provides 32 user channels ( 64 kbit/s ) on an E1 ( 2.0 Mbit/s ) and 512 user channels or 16 E1s on an E3 ( 34.4 Mbit/s ). Synchronous Optical Networking (SONET, in
749-453: A better quality of service for time critical services even on extremely busy networks. However, overuse can lead to concerns about fairness and network neutrality or even charges of censorship , when some types of traffic are severely or completely blocked. An Internet blackout or outage can be caused by local signaling interruptions. Disruptions of submarine communications cables may cause blackouts or slowdowns to large areas, such as in
856-478: A built-in keyboard and display for the console. Some Unix-like operating systems such as Linux and FreeBSD have virtual consoles to provide several text terminals on a single computer. The fundamental type of application running on a text terminal is a command-line interpreter or shell , which prompts for commands from the user and executes each command after a press of Return . This includes Unix shells and some interactive programming environments. In
963-510: A connection to the Internet through the telephone network. Unlike dial-up, DSL can operate using a single phone line without preventing normal use of the telephone line for voice phone calls. DSL uses the high frequencies, while the low (audible) frequencies of the line are left free for regular telephone communication. These frequency bands are subsequently separated by filters installed at the customer's premises. DSL originally stood for "digital subscriber loop". In telecommunications marketing,
1070-427: A few hours. When the Internet is accessed using a modem, digital data is converted to analog for transmission over analog networks such as the telephone and cable networks. A computer or other device accessing the Internet would either be connected directly to a modem that communicates with an Internet service provider (ISP) or the modem's Internet connection would be shared via a LAN which provides access in
1177-430: A field that may have previously required a full screen-full of characters to be re-sent from the computer, possibly over a slow modem line. Around the mid-1980s most intelligent terminals, costing less than most dumb terminals would have a few years earlier, could provide enough user-friendly local editing of data and send the completed form to the main computer. Providing even more processing possibilities, workstations like
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#17330855174541284-845: A full DS3. Higher data rates are delivered in OC-3c multiples of four providing OC-12c ( 622.080 Mbit/s ), OC-48c ( 2.488 Gbit/s ), OC-192c ( 9.953 Gbit/s ), and OC-768c ( 39.813 Gbit/s ). The "c" at the end of the OC labels stands for "concatenated" and indicates a single data stream rather than several multiplexed data streams. Optical transport network (OTN) may be used instead of SONET for higher data transmission speeds of up to 400 Gbit/s per OTN channel. The 1 , 10 , 40, and 100 Gigabit Ethernet IEEE standards (802.3) allow digital data to be delivered over copper wiring at distances to 100 m and over optical fiber at distances to 40 km . Cable Internet provides access using
1391-530: A green or amber screen. Typically terminals communicate with the computer via a serial port via a null modem cable, often using an EIA RS-232 or RS-422 or RS-423 or a current loop serial interface. IBM systems typically communicated over a Bus and Tag channel, a coaxial cable using a proprietary protocol, a communications link using Binary Synchronous Communications or IBM's SNA protocol, but for many DEC, Data General and NCR (and so on) computers there were many visual display suppliers competing against
1498-610: A keyboard in 1941, as did the Z4 in 1942–1945. However, these consoles could only be used to enter numeric inputs and were thus analogous to those of calculating machines; programs, commands, and other data were entered via paper tape. Both machines had a row of display lamps for results. In 1956, the Whirlwind Mark ;I computer became the first computer equipped with a keyboard-printer combination with which to support direct input of data and commands and output of results. That device
1605-457: A library such as ncurses . For more complex operations, the programs can use terminal specific ioctl system calls. For an application, the simplest way to use a terminal is to simply write and read text strings to and from it sequentially. The output text is scrolled, so that only the last several lines (typically 24) are visible. Unix systems typically buffer the input text until the Enter key
1712-552: A limited area such as a home, school, computer laboratory, or office building. Although a connection to a LAN may provide very high data-rates within the LAN, actual Internet access speed is limited by the upstream link to the ISP. LANs may be wired or wireless. Ethernet over twisted pair cabling and Wi-Fi are the two most common technologies used to build LANs today, but ARCNET , Token Ring , LocalTalk , FDDI , and other technologies were used in
1819-632: A line of data from a keyboard over a serial or other interface. Starting in the mid-1970s with microcomputers such as the Sphere 1 , Sol-20 , and Apple I , display circuitry and keyboards began to be integrated into personal and workstation computer systems, with the computer handling character generation and outputting to a CRT display such as a computer monitor or, sometimes, a consumer TV, but most larger computers continued to require terminals. Early terminals were inexpensive devices but very slow compared to punched cards or paper tape for input; with
1926-607: A microprocessor is built in, but not all terminals with microprocessors did any real processing of input: the main computer to which it was attached would have to respond quickly to each keystroke. The term "intelligent" in this context dates from 1969. Notable examples include the IBM 2250 , predecessor to the IBM 3250 and IBM 5080, and IBM 2260 , predecessor to the IBM 3270 , introduced with System/360 in 1964. Most terminals were connected to minicomputers or mainframe computers and often had
2033-409: A modem and a phone call placed over the public switched telephone network (PSTN) to connect to a pool of modems operated by an ISP. The modem converts a computer's digital signal into an analog signal that travels over a phone line's local loop until it reaches a telephone company's switching facilities or central office (CO) where it is switched to another phone line that connects to another modem at
2140-594: A real-world terminal, sometimes allowing concurrent use of local programs and access to a distant terminal host system, either over a direct serial connection or over a network using, e.g., SSH . Today few if any dedicated computer terminals are being manufactured, as time sharing on large computers has been replaced by personal computers, handheld devices and workstations with graphical user interfaces. User interactions with servers use either software such as Web browsers , or terminal emulators, with connections over high-speed networks. The console of Konrad Zuse 's Z3 had
2247-414: A replacement for T1 and Frame Relay lines for corporate and institutional customers, or offer carrier-grade Ethernet. The use of optical fiber offers much higher data rates over relatively longer distances. Most high-capacity Internet and cable television backbones already use fiber optic technology, with data switched to other technologies (DSL, cable, LTE) for final delivery to customers. Fiber optic
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#17330855174542354-593: A sequence of codes were sent to the terminal to try to read the cursor's position or the 25th line's contents using a sequence of different manufacturer's control code sequences, and the terminal-generated response would determine a single-digit number (such as 6 for Data General Dasher terminals, 4 for ADM 3A/5/11/12 terminals, 0 or 2 for TTYs with no special features) that would be available to programs to say which set of codes to use. The great majority of terminals were monochrome, manufacturers variously offering green, white or amber and sometimes blue screen phosphors. (Amber
2461-408: A service to become oversubscribed, resulting in congestion and poor performance. The TCP protocol includes flow-control mechanisms that automatically throttle back on the bandwidth being used during periods of network congestion . This is fair in the sense that all users who experience congestion receive less bandwidth, but it can be frustrating for customers and a major problem for ISPs. In some cases,
2568-472: A shell, most of the commands are small applications themselves. Another important application type is that of the text editor . A text editor typically occupies the full area of display, displays one or more text documents, and allows the user to edit the documents. The text editor has, for many uses, been replaced by the word processor , which usually provides rich formatting features that the text editor lacks. The first word processors used text to communicate
2675-577: A speed of 56 kbit/s , as they are primarily made using modems that operate at a maximum data rate of 56 kbit/s downstream (towards the end user) and 34 or 48 kbit/s upstream (toward the global Internet). Multilink dial-up provides increased bandwidth by channel bonding multiple dial-up connections and accessing them as a single data channel. It requires two or more modems, phone lines, and dial-up accounts, as well as an ISP that supports multilinking – and of course any line and data charges are also doubled. This inverse multiplexing option
2782-455: A standard, AlphaWindows , that would allow a single CRT screen to implement multiple windows, each of which was to behave as a distinct terminal. Unfortunately, like I2O , this suffered from being run as a closed standard: non-members were unable to obtain even minimal information and there was no realistic way a small company or independent developer could join the consortium. An intelligent terminal does its own processing, usually implying
2889-446: A terminal as "intelligent" was its ability to process user-input within the terminal—not interrupting the main computer at each keystroke—and send a block of data at a time (for example: when the user has finished a whole field or form). Most terminals in the early 1980s, such as ADM-3A, TVI912, Data General D2, DEC VT52 , despite the introduction of ANSI terminals in 1978, were essentially "dumb" terminals, although some of them (such as
2996-456: A typical application the host sends the terminal a preformatted panel containing both static data and fields into which data may be entered. The terminal operator keys data, such as updates in a database entry, into the appropriate fields. When entry is complete (or ENTER or PF key pressed on 3270s), a block of data, usually just the data entered by the operator (modified data), is sent to the host in one transmission. The 3270 terminal buffer (at
3103-402: Is " thin client ". A thin client typically uses a protocol like X11 for Unix terminals, or RDP for Microsoft Windows. The bandwidth needed depends on the protocol used, the resolution, and the color depth . Modern graphic terminals allow display of images in color, and of text in varying sizes, colors, and fonts (type faces). In the early 1990s, an industry consortium attempted to define
3210-406: Is a serial computer interface for text entry and display. Information is presented as an array of pre-selected formed characters . When such devices use a video display such as a cathode-ray tube , they are called a " video display unit " or "visual display unit" (VDU) or "video display terminal" (VDT). The system console is often a text terminal used to operate a computer. Modern computers have
3317-658: Is a switched telephone service capable of transporting voice and digital data, and is one of the oldest Internet access methods. ISDN has been used for voice, video conferencing, and broadband data applications. ISDN was very popular in Europe, but less common in North America. Its use peaked in the late 1990s before the availability of DSL and cable modem technologies. Basic rate ISDN, known as ISDN-BRI, has two 64 kbit/s "bearer" or "B" channels. These channels can be used separately for voice or data calls or bonded together to provide
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3424-522: Is a type of computer terminal that communicates with its host in blocks of data, as opposed to a character-oriented terminal that communicates with its host one character at a time. A block-oriented terminal may be card-oriented, display-oriented, keyboard-display, keyboard-printer, printer or some combination. The IBM 3270 is perhaps the most familiar implementation of a block-oriented display terminal, but most mainframe computer manufacturers and several other companies produced them. The description below
3531-495: Is achieved via RS-232 serial links, Ethernet or other proprietary protocols . Character-oriented terminals can be "dumb" or "smart". Dumb terminals are those that can interpret a limited number of control codes (CR, LF, etc.) but do not have the ability to process special escape sequences that perform functions such as clearing a line, clearing the screen, or controlling cursor position. In this context dumb terminals are sometimes dubbed glass Teletypes , for they essentially have
3638-539: Is based on the IEEE 802.11g ( WiFi ) standard and also supports IEEE 802.11b devices. It is significant as it marks BTs departure away from traditional telecommunications services and towards Internet and media products. It supports VoIP Internet calls and is compatible with existing DECT handsets. It works with the existing BT Fusion service and works with the BT Vision video on demand service. The device connects to
3745-484: Is capable of supporting applications such as high-definition television, as well as telephone services ( voice over IP ) and general Internet access, over a single physical connection. VDSL2 ( ITU-T G.993.2 ) is a second-generation version and an enhancement of VDSL. Approved in February 2006, it is able to provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. However,
3852-516: Is immune to electromagnetic interference. In 2010, Australia began rolling out its National Broadband Network across the country using fiber-optic cables to 93 percent of Australian homes, schools, and businesses. The project was abandoned by the subsequent LNP government, in favor of a hybrid FTTN design, which turned out to be more expensive and introduced delays. Similar efforts are underway in Italy, Canada, India, and many other countries (see Fiber to
3959-462: Is in terms of the 3270, but similar considerations apply to other types. Block-oriented terminals typically incorporate a buffer which stores one screen or more of data, and also stores data attributes, not only indicating appearance (color, brightness, blinking, etc.) but also marking the data as being enterable by the terminal operator vs. protected against entry, as allowing the entry of only numeric information vs. allowing any characters, etc. In
4066-400: Is limited, the number of concurrent lines that can be displayed at one time is limited. Vector-mode displays were historically important but are no longer used. Practically all modern graphic displays are raster-mode, descended from the picture scanning techniques used for television , in which the visual elements are a rectangular array of pixels . Since the raster image is only perceptible to
4173-1200: Is not readily available. Newer technologies being deployed for fixed (stationary) and mobile broadband access include WiMAX , LTE , and fixed wireless . Starting in roughly 2006, mobile broadband access is increasingly available at the consumer level using " 3G " and " 4G " technologies such as HSPA , EV-DO , HSPA+ , and LTE . In addition to access from home, school, and the workplace Internet access may be available from public places such as libraries and Internet cafés , where computers with Internet connections are available. Some libraries provide stations for physically connecting users' laptops to LANs. Wireless Internet access points are available in public places such as airport halls, in some cases just for brief use while standing. Some access points may also provide coin-operated computers. Various terms are used, such as "public Internet kiosk ", "public access terminal", and "Web payphone ". Many hotels also have public terminals, usually fee based. Coffee shops, shopping malls, and other venues increasingly offer wireless access to computer networks, referred to as hotspots , for users who bring their own wireless-enabled devices such as
4280-444: Is pressed, so the application receives a ready string of text. In this mode, the application need not know much about the terminal. For many interactive applications this is not sufficient. One of the common enhancements is command-line editing (assisted with such libraries as readline ); it also may give access to command history. This is very helpful for various interactive command-line interpreters. Even more advanced interactivity
4387-428: Is provided with full-screen applications. Those applications completely control the screen layout; also they respond to key-pressing immediately. This mode is very useful for text editors, file managers and web browsers . In addition, such programs control the color and brightness of text on the screen, and decorate it with underline, blinking and special characters (e.g. box-drawing characters ). To achieve all this,
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4494-425: Is the building block of the Internet telecommunications networks . The laser , originally demonstrated by Charles H. Townes and Arthur Leonard Schawlow in 1960, was adopted for MOS light-wave systems around 1980, which led to exponential growth of Internet bandwidth . Continuous MOSFET scaling has since led to online bandwidth doubling every 18 months ( Edholm's law , which is related to Moore's law ), with
4601-597: Is yet to have been implemented in real-world usage. Broadband cable access tends to service fewer business customers because existing television cable networks tend to service residential buildings; commercial buildings do not always include wiring for coaxial cable networks. In addition, because broadband cable subscribers share the same local line, communications may be intercepted by neighboring subscribers. Cable networks regularly provide encryption schemes for data traveling to and from customers, but these schemes may be thwarted. Digital subscriber line (DSL) service provides
4708-406: The 2008 submarine cable disruption . Less-developed countries are more vulnerable due to a small number of high-capacity links. Land cables are also vulnerable, as in 2011 when a woman digging for scrap metal severed most connectivity for the nation of Armenia. Internet blackouts affecting almost entire countries can be achieved by governments as a form of Internet censorship , as in the blockage of
4815-589: The CCITT standards body defined "broadband service" as requiring transmission channels capable of supporting bit rates greater than the primary rate which ranged from about 1.5 to 2 Mbit/s. A 2006 Organisation for Economic Co-operation and Development (OECD) report defined broadband as having download data transfer rates equal to or faster than 256 kbit/s. And in 2015 the U.S. Federal Communications Commission (FCC) defined "Basic Broadband" as data transmission speeds of at least 25 Mbit/s downstream (from
4922-500: The IBM 2741 (1965) and the DECwriter (1970). Respective top speeds of teletypes, IBM 2741 and the LA30 (an early DECwriter) were 10, 15 and 30 characters per second. Although at that time "paper was king" the speed of interaction was relatively limited. The DECwriter was the last major printing-terminal product. It faded away after 1980 under pressure from video display units (VDUs), with
5029-742: The Intel 8080 . This made them inexpensive and they quickly became extremely popular input-output devices on many types of computer system, often replacing earlier and more expensive printing terminals. After 1970 several suppliers gravitated to a set of common standards: The experimental era of serial VDUs culminated with the VT100 in 1978. By the early 1980s, there were dozens of manufacturers of terminals, including Lear-Siegler , ADDS , Data General, DEC , Hazeltine Corporation , Heath/Zenith , Hewlett-Packard , IBM, TeleVideo , Volker-Craig, and Wyse , many of which had incompatible command sequences (although many used
5136-512: The Internet in Egypt , whereby approximately 93% of networks were without access in 2011 in an attempt to stop mobilization for anti-government protests . On April 25, 1997, due to a combination of human error and a software bug, an incorrect routing table at MAI Network Service (a Virginia Internet service provider ) propagated across backbone routers and caused major disruption to Internet traffic for
5243-498: The VT220 terminal strongly influenced the Model M shipped on IBM PCs from 1985, and through it all later computer keyboards. Although flat-panel displays were available since the 1950s, cathode-ray tubes continued to dominate the market until the personal computer had made serious inroads into the display terminal market. By the time cathode-ray tubes on PCs were replaced by flatscreens after
5350-481: The point-to-point protocol (PPP) extended the Internet protocols and made the full range of Internet services available to dial-up users; although slower, due to the lower data rates available using dial-up. An important factor in the rapid rise of Internet access speed has been advances in MOSFET (MOS transistor) technology. The MOSFET invented at Bell Labs between 1955 and 1960 following Frosch and Derick discoveries,
5457-545: The 1990s, the National Information Infrastructure initiative in the U.S. made broadband Internet access a public policy issue. In 2000, most Internet access to homes was provided using dial-up, while many businesses and schools were using broadband connections. In 2000 there were just under 150 million dial-up subscriptions in the 34 OECD countries and fewer than 20 million broadband subscriptions. By 2004, broadband had grown and dial-up had declined so that
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#17330855174545564-573: The ASR Teletype models, included a paper tape reader and punch which could record output such as a program listing. The data on the tape could be re-entered into the computer using the tape reader on the teletype, or printed to paper. Teletypes used the current loop interface that was already used in telegraphy. A less expensive Read Only (RO) configuration was available for the Teletype. Custom-designs keyboard/printer terminals that came later included
5671-560: The Internet to the user's computer ) and 3 Mbit/s upstream (from the user's computer to the Internet). The trend is to raise the threshold of the broadband definition as higher data rate services become available. The higher data rate dial-up modems and many broadband services are "asymmetric"—supporting much higher data rates for download (toward the user) than for upload (toward the Internet). Data rates, including those given in this article, are usually defined and advertised in terms of
5778-594: The Internet using a standard ADSL connection. It will be able to support the WBC products using ADSL2+ (up to 24 Mb) when BT Wholesale launches them in April 2008. BT launched a new look Home Hub in October 2007 with an enhanced wireless footprint. In July 2008 the Home Hub was relaunched with a new smaller design, Draft-N wireless, additional connections and a new user interface; unlike
5885-539: The Internet using a variety of means – usually fiber optic cable or digital satellite and microwave transmissions. Like DSL, broadband cable provides a continuous connection with an ISP. Downstream , the direction toward the user, bit rates can be as much as 1000 Mbit/s in some countries, with the use of DOCSIS 3.1. Upstream traffic, originating at the user, ranges from 384 kbit/s to more than 50 Mbit/s. DOCSIS 4.0 promises up to 10 Gbit/s downstream and 6 Gbit/s upstream, however this technology
5992-584: The U.S. and Canada) and Synchronous Digital Hierarchy (SDH, in the rest of the world) are the standard multiplexing protocols used to carry high-data-rate digital bit-streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At lower transmission rates data can also be transferred via an electrical interface. The basic unit of framing is an OC-3c (optical) or STS-3c (electrical) which carries 155.520 Mbit/s . Thus an OC-3c will carry three OC-1 (51.84 Mbit/s) payloads each of which has enough capacity to include
6099-619: The US, but grew over time to include most of the world's large universities and the research arms of many technology companies. Use by a wider audience only came in 1995 when restrictions on the use of the Internet to carry commercial traffic were lifted. In the early to mid-1980s, most Internet access was from personal computers and workstations directly connected to local area networks (LANs) or from dial-up connections using modems and analog telephone lines . LANs typically operated at 10 Mbit/s while modem data-rates grew from 1200 bit/s in
6206-647: The additional functionality to host a LAN so most Internet access today is through a LAN such as that created by a WiFi router connected to a modem or a combo modem router, often a very small LAN with just one or two devices attached. And while LANs are an important form of Internet access, this raises the question of how and at what data rate the LAN itself is connected to the rest of the global Internet. The technologies described below are used to make these connections, or in other words, how customers' modems ( Customer-premises equipment ) are most often connected to internet service providers (ISPs). Dial-up Internet access uses
6313-446: The advent of time-sharing systems, terminals slowly pushed these older forms of interaction from the industry. Related developments were the improvement of terminal technology and the introduction of inexpensive video displays . Early Teletypes only printed out with a communications speed of only 75 baud or 10 5-bit characters per second, and by the 1970s speeds of video terminals had improved to 2400 or 9600 2400 bit/s . Similarly,
6420-417: The amount of bandwidth actually available may fall below the threshold required to support a particular service such as video conferencing or streaming live video–effectively making the service unavailable. When traffic is particularly heavy, an ISP can deliberately throttle back the bandwidth available to classes of users or for particular services. This is known as traffic shaping and careful use can ensure
6527-642: The application must deal not only with plain text strings, but also with control characters and escape sequences, which allow moving the cursor to an arbitrary position, clearing portions of the screen, changing colors and displaying special characters, and also responding to function keys. The great problem here is that there are many different terminals and terminal emulators, each with its own set of escape sequences. In order to overcome this, special libraries (such as curses ) have been created, together with terminal description databases, such as Termcap and Terminfo. A block-oriented terminal or block mode terminal
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#17330855174546634-418: The bandwidths of telecommunications networks rising from bits per second to terabits per second . Broadband Internet access, often shortened to just broadband, is simply defined as "Internet access that is always on, and faster than the traditional dial-up access" and so covers a wide range of technologies. The core of these broadband Internet technologies are complementary MOS (CMOS) digital circuits ,
6741-429: The capabilities of that mobile network. The bit rates for dial-up modems range from as little as 110 bit/s in the late 1950s, to a maximum of from 33 to 64 kbit/s ( V.90 and V.92 ) in the late 1990s. Dial-up connections generally require the dedicated use of a telephone line. Data compression can boost the effective bit rate for a dial-up modem connection from 220 ( V.42bis ) to 320 ( V.44 ) kbit/s. However,
6848-556: The computer manufacturer for terminals to expand the systems. In fact, the instruction design for the Intel 8008 was originally conceived at Computer Terminal Corporation as the processor for the Datapoint 2200 . From the introduction of the IBM 3270 , and the DEC VT100 (1978), the user and programmer could notice significant advantages in VDU technology improvements, yet not all programmers used
6955-588: The development of the VDU were the Univac Uniscope and the IBM 2260 , both in 1964. These were block-mode terminals designed to display a page at a time, using proprietary protocols; in contrast to character-mode devices, they enter data from the keyboard into a display buffer rather than transmitting them immediately. In contrast to later character-mode devices, the Uniscope used synchronous serial communication over an EIA RS-232 interface to communicate between
7062-473: The device) could be updated on a single character basis, if necessary, because of the existence of a "set buffer address order" (SBA), that usually preceded any data to be written/overwritten within the buffer. A complete buffer could also be read or replaced using the READ BUFFER command or WRITE command (unformatted or formatted in the case of the 3270). Block-oriented terminals cause less system load on
7169-423: The display, as well as the ability to switch emulation modes to mimic competitor's models, that became increasingly important selling features during the 1980s especially, when buyers could mix and match different suppliers' equipment to a greater extent than before. The advance in microprocessors and lower memory costs made it possible for the terminal to handle editing operations such as inserting characters within
7276-503: The early 1980s to 56 kbit/s by the late 1990s. Initially, dial-up connections were made from terminals or computers running terminal-emulation software to terminal servers on LANs. These dial-up connections did not support end-to-end use of the Internet protocols and only provided terminal-to-host connections. The introduction of network access servers supporting the Serial Line Internet Protocol (SLIP) and later
7383-554: The early ADM-3 as a starting point). The great variations in the control codes between makers gave rise to software that identified and grouped terminal types so the system software would correctly display input forms using the appropriate control codes; In Unix-like systems the termcap or terminfo files, the stty utility, and the TERM environment variable would be used; in Data General's Business BASIC software, for example, at login-time
7490-514: The effectiveness of data compression is quite variable, depending on the type of data being sent, the condition of the telephone line, and a number of other factors. In reality, the overall data rate rarely exceeds 150 kbit/s. Broadband technologies supply considerably higher bit rates than dial-up, generally without disrupting regular telephone use. Various minimum data rates and maximum latencies have been used in definitions of broadband, ranging from 64 kbit/s up to 4.0 Mbit/s. In 1988
7597-573: The end user on optical fibers. The differences between the methods have mostly to do with just how close to the end user the delivery on fiber comes. All of these delivery methods are similar in function and architecture to hybrid fiber-coaxial (HFC) systems used to provide cable Internet access. Fiber internet connections to customers are either AON ( Active optical network ) or more commonly PON ( Passive optical network ). Examples of fiber optic internet access standards are G.984 (GPON, G-PON) and 10G-PON (XG-PON). ISPs may instead use Metro Ethernet as
7704-615: The fact that early character-mode terminals were often deployed to replace teletype machines as a way to reduce operating costs. The next generation of VDUs went beyond teletype emulation with an addressable cursor that gave them the ability to paint two-dimensional displays on the screen. Very early VDUs with cursor addressibility included the VT05 and the Hazeltine 2000 operating in character mode, both from 1970. Despite this capability, early devices of this type were often called "Glass TTYs". Later,
7811-456: The features of the new terminals ( backward compatibility in the VT100 and later TeleVideo terminals, for example, with "dumb terminals" allowed programmers to continue to use older software). Some dumb terminals had been able to respond to a few escape sequences without needing microprocessors: they used multiple printed circuit boards with many integrated circuits ; the single factor that classed
7918-596: The general public began with the commercialization of the early Internet in the early 1990s, and has grown with the availability of useful applications, such as the World Wide Web. In 1995, only 0.04 percent of the world's population had access, with well over half of those living in the United States and consumer use was through dial-up . By the first decade of the 21st century, many consumers in developed nations used faster broadband technology. By 2014, 41 percent of
8025-548: The host and less network traffic than character-oriented terminals. They also appear more responsive to the user, especially over slow connections, since editing within a field is done locally rather than depending on echoing from the host system. Early terminals had limited editing capabilities – 3270 terminals, for example, only could check entries as valid numerics. Subsequent "smart" or "intelligent" terminals incorporated microprocessors and supported more local processing. Programmers of block-oriented terminals often used
8132-505: The host computer for its processing power is called a " dumb terminal " or a thin client . In the era of serial ( RS-232 ) terminals there was a conflicting usage of the term "smart terminal" as a dumb terminal with no user-accessible local computing power but a particularly rich set of control codes for manipulating the display; this conflict was not resolved before hardware serial terminals became obsolete. A personal computer can run terminal emulator software that replicates functions of
8239-429: The human eye as a whole for a very short time, the raster must be refreshed many times per second to give the appearance of a persistent display. The electronic demands of refreshing display memory meant that graphic terminals were developed much later than text terminals, and initially cost much more. Most terminals today are graphical; that is, they can show images on the screen. The modern term for graphical terminal
8346-806: The last revision (the DECwriter IV of 1982) abandoning the classic teletypewriter form for one more resembling a desktop printer. A video display unit (VDU) displays information on a screen rather than printing text to paper and typically uses a cathode-ray tube (CRT). VDUs in the 1950s were typically designed for displaying graphical data rather than text and were used in, e.g., experimental computers at institutions like MIT ; computers used in academia, government and business, sold under brand names like DEC , ERA , IBM and UNIVAC ; military computers supporting specific defence applications such as ballistic missile warning systems and radar/air defence coordination systems like BUIC and SAGE . Two early landmarks in
8453-431: The later ADM and TVI models) did have a primitive block-send capability. Common early uses of local processing power included features that had little to do with off-loading data processing from the host computer but added useful features such as printing to a local printer, buffered serial data transmission and serial handshaking (to accommodate higher serial transfer speeds), and more sophisticated character attributes for
8560-650: The maximum data rate is achieved at a range of about 300 meters and performance degrades as distance and loop attenuation increases. DSL Rings (DSLR) or Bonded DSL Rings is a ring topology that uses DSL technology over existing copper telephone wires to provide data rates of up to 400 Mbit/s. Fiber-to-the-home (FTTH) is one member of the Fiber-to-the-x (FTTx) family that includes Fiber-to-the-building or basement (FTTB), Fiber-to-the-premises (FTTP), Fiber-to-the-desk (FTTD), Fiber-to-the-curb (FTTC), and Fiber-to-the-node (FTTN). These methods all bring data closer to
8667-510: The maximum or peak download rate. In practice, these maximum data rates are not always reliably available to the customer. Actual end-to-end data rates can be lower due to a number of factors. In late June 2016, internet connection speeds averaged about 6 Mbit/s globally. Physical link quality can vary with distance and for wireless access with terrain, weather, building construction, antenna placement, and interference from other radio sources. Network bottlenecks may exist at points anywhere on
8774-404: The multiplexer and the host, while the 2260 used either a channel connection or asynchronous serial communication between the 2848 and the host. The 2265, related to the 2260, also used asynchronous serial communication. The Datapoint 3300 from Computer Terminal Corporation , announced in 1967 and shipped in 1969, was a character-mode device that emulated a Model 33 Teletype . This reflects
8881-527: The number of subscriptions were roughly equal at 130 million each. In 2010, in the OECD countries, over 90% of the Internet access subscriptions used broadband, broadband had grown to more than 300 million subscriptions, and dial-up subscriptions had declined to fewer than 30 million. The broadband technologies in widest use are of digital subscriber line (DSL), ADSL , and cable Internet access . Newer technologies include VDSL and optical fiber extended closer to
8988-407: The operator attempted to enter more data into the field than allowed. A graphical terminal can display images as well as text. Graphical terminals are divided into vector-mode terminals, and raster mode . A vector-mode display directly draws lines on the face of a cathode-ray tube under control of the host computer system. The lines are continuously formed, but since the speed of electronics
9095-451: The past. Ethernet is the name of the IEEE 802.3 standard for physical LAN communication and Wi-Fi is a trade name for a wireless local area network (WLAN) that uses one of the IEEE 802.11 standards. Ethernet cables are interconnected via switches & routers. Wi-Fi networks are built using one or more wireless antenna called access points . Many "modems" ( cable modems , DSL gateways or Optical Network Terminals (ONTs)) provide
9202-614: The path from the end-user to the remote server or service being used and not just on the first or last link providing Internet access to the end-user. Users may share access over a common network infrastructure. Since most users do not use their full connection capacity all of the time, this aggregation strategy (known as contended service ) usually works well, and users can burst to their full data rate at least for brief periods. However, peer-to-peer (P2P) file sharing and high-quality streaming video can require high data-rates for extended periods, which violates these assumptions and can cause
9309-556: The premises by country). Power-line Internet , also known as Broadband over power lines (BPL), carries Internet data on a conductor that is also used for electric power transmission . Because of the extensive power line infrastructure already in place, this technology can provide people in rural and low population areas access to the Internet with little cost in terms of new transmission equipment, cables, or wires. Data rates are asymmetric and generally range from 256 kbit/s to 2.7 Mbit/s. Because these systems use parts of
9416-764: The previous replacement, the new Home Hub was given a .0 release, making it the Home Hub 2.0. In January 2010, BT launched a new product called BT Infinity . 4 million homes in the UK are covered by this service. Most homes will get FTTC service and have up to 40 Mbit/s broadband, those with FTTP will get 100 Mbit/s and a 20 GB monthly usage allowance in 2010, with an unlimited package also offered. BT have since rolled out Infinity 2 offering up to 79 Mbit/s download and 19 Mbit/s upload with an unlimited package. Infinity customers are allowed to upgrade to Infinity 2, but must restart their 18-month contract. Internet access The availability of Internet access to
9523-488: The radio spectrum allocated to other over-the-air communication services, interference between the services is a limiting factor in the introduction of power-line Internet systems. The IEEE P1901 standard specifies that all power-line protocols must detect existing usage and avoid interfering with it. Computer terminal A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from,
9630-408: The remote end of the connection. Operating on a single channel, a dial-up connection monopolizes the phone line and is one of the slowest methods of accessing the Internet. Dial-up is often the only form of Internet access available in rural areas as it requires no new infrastructure beyond the already existing telephone network, to connect to the Internet. Typically, dial-up connections do not exceed
9737-468: The same limited functionality as does a mechanical Teletype. This type of dumb terminal is still supported on modern Unix-like systems by setting the environment variable TERM to dumb . Smart or intelligent terminals are those that also have the ability to process escape sequences, in particular the VT52, VT100 or ANSI escape sequences. A text terminal , or often just terminal (sometimes text console )
9844-413: The screen usually causes the terminal to scroll down one line, entering data into the last screen position on a block-oriented terminal usually causes the cursor to wrap — move to the start of the first enterable field. Programmers might "protect" the last screen position to prevent inadvertent wrap. Likewise a protected field following an enterable field might lock the keyboard and sound an audible alarm if
9951-926: The service provider. Leased lines are dedicated lines used primarily by ISPs, business, and other large enterprises to connect LANs and campus networks to the Internet using the existing infrastructure of the public telephone network or other providers. Delivered using wire, optical fiber , and radio , leased lines are used to provide Internet access directly as well as the building blocks from which several other forms of Internet access are created. T-carrier technology dates to 1957 and provides data rates that range from 56 and 64 kbit/s ( DS0 ) to 1.5 Mbit/s ( DS1 or T1), to 45 Mbit/s ( DS3 or T3). A T1 line carries 24 voice or data channels (24 DS0s), so customers may use some channels for data and others for voice traffic or use all 24 channels for clear channel data. A DS3 (T3) line carries 28 DS1 (T1) channels. Fractional T1 lines are also available in multiples of
10058-415: The simplest form, a text terminal is like a file. Writing to the file displays the text and reading from the file produces what the user enters. In Unix-like operating systems, there are several character special files that correspond to available text terminals. For other operations, there are special escape sequences , control characters and termios functions that a program can use, most easily via
10165-511: The speed capabilities of which were extended with innovative design techniques. Broadband connections are typically made using a computer's built in Ethernet networking capabilities, or by using a NIC expansion card . Most broadband services provide a continuous "always on" connection; there is no dial-in process required, and it does not interfere with voice use of phone lines. Broadband provides improved access to Internet services such as: In
10272-441: The speed of remote batch terminals had improved to 4800 bit/s at the beginning of the decade and 19.6 kbps by the end of the decade, with higher speeds possible on more expensive terminals. The function of a terminal is typically confined to transcription and input of data; a device with significant local, programmable data-processing capability may be called a "smart terminal" or fat client . A terminal that depends on
10379-439: The structure of the document, but later word processors operate in a graphical environment and provide a WYSIWYG simulation of the formatted output. However, text editors are still used for documents containing markup such as DocBook or LaTeX . Programs such as Telix and Minicom control a modem and the local terminal to let the user interact with remote servers. On the Internet , telnet and ssh work similarly. In
10486-607: The subscriber in both telephone and cable plants. Fiber-optic communication , while only recently being used in premises and to the curb schemes, has played a crucial role in enabling broadband Internet access by making transmission of information at very high data rates over longer distances much more cost-effective than copper wire technology. In areas not served by ADSL or cable, some community organizations and local governments are installing Wi-Fi networks. Wireless, satellite, and microwave Internet are often used in rural, undeveloped, or other hard to serve areas where wired Internet
10593-504: The technique of storing context information for the transaction in progress on the screen, possibly in a hidden field, rather than depending on a running program to keep track of status. This was the precursor of the HTML technique of storing context in the URL as data to be passed as arguments to a CGI program. Unlike a character-oriented terminal, where typing a character into the last position of
10700-470: The term "glass TTY" tended to be restrospectively narrowed to devices without full cursor addressibility. The classic era of the VDU began in the early 1970s and was closely intertwined with the rise of time sharing computers . Important early products were the ADM-3A , VT52 , and VT100 . These devices used no complicated CPU , instead relying on individual logic gates , LSI chips, or microprocessors such as
10807-410: The term digital subscriber line is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed variety of DSL. The data throughput of consumer DSL services typically ranges from 256 kbit/s to 20 Mbit/s in the direction to the customer (downstream), depending on DSL technology, line conditions, and service-level implementation. In ADSL, the data throughput in
10914-593: The upstream direction, (i.e., in the direction to the service provider) is lower than that in the downstream direction (i.e. to the customer), hence the designation of asymmetric. With a symmetric digital subscriber line (SDSL), the downstream and upstream data rates are equal. Very-high-bit-rate digital subscriber line (VDSL or VHDSL, ITU G.993.1) is a digital subscriber line (DSL) standard approved in 2001 that provides data rates up to 52 Mbit/s downstream and 16 Mbit/s upstream over copper wires and up to 85 Mbit/s down- and upstream on coaxial cable. VDSL
11021-545: The world's population had access, broadband was almost ubiquitous worldwide, and global average connection speeds exceeded one megabit per second. Types of connections range from fixed cable home (such as DSL and fiber optic ) to mobile (via cellular ) and satellite . The Internet developed from the ARPANET , which was funded by the US government to support projects within the government, at universities and research laboratories in
11128-417: The year 2000, the hardware computer terminal was nearly obsolete. A character-oriented terminal is a type of computer terminal that communicates with its host one character at a time, as opposed to a block-oriented terminal that communicates in blocks of data. It is the most common type of data terminal, because it is easy to implement and program. Connection to the mainframe computer or terminal server
11235-588: Was a Friden Flexowriter , which would continue to serve this purpose on many other early computers well into the 1960s. Early user terminals connected to computers were, like the Flexowriter, electromechanical teleprinters /teletypewriters (TeleTYpewriter, TTY), such as the Teletype Model ;33 , originally used for telegraphy ; early Teletypes were typically configured as Keyboard Send-Receive (KSR) or Automatic Send-Receive (ASR). Some terminals, such as
11342-451: Was briefly popular with some high-end users before ISDN, DSL and other technologies became available. Diamond and other vendors created special modems to support multilinking. The term broadband includes a broad range of technologies, all of which provide higher data rate access to the Internet. The following technologies use wires or cables in contrast to wireless broadband described later. Integrated Services Digital Network (ISDN)
11449-495: Was claimed to reduce eye strain). Terminals with modest color capability were also available but not widely used; for example, a color version of the popular Wyse WY50, the WY350, offered 64 shades on each character cell. VDUs were eventually displaced from most applications by networked personal computers, at first slowly after 1985 and with increasing speed in the 1990s. However, they had a lasting influence on PCs. The keyboard layout of
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