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Encyclopedia > Computer terminal

A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system. Typically it provides a text terminal interface over a serial line. Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. ... A BlueGene supercomputer cabinet. ... Memory (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ... A typical text terminal produces input and displays output and errors A text terminal or often just terminal (sometimes text console) is a serial computer interface for text entry and display. ... A male DE-9 serial port on the rear panel of a PC. In computing, a serial port consists of an interface on a computer system through which information transfers in or out one bit at a time (contrast parallel port). ...

Contents

Historical

Early user terminals connected to computers were generally electromechanical teleprinters (TTYs), such as the model 33 Teletype. However these were too slow for most production uses. By the early 1970s, many in the computer industry realized that an affordable video data entry terminal could supplant the ubiquitous punch cards and permit new uses for computers that would be more interactive. The problem was that the amount of memory needed to store the information on a page of text was comparable to the memory in low end minicomputers then in use. Displaying the information at video speeds was also a challenge and the necessary control logic took up a rack worth of pre-integrated circuit electronics. One company announced plans to build a video terminal for $15,000 and attracted a large backlog of orders, but folded when their engineering plans, which included fabricating their own ICs, proved too ambitious. Another approach involved the use of the storage tube, a specialized CRT developed by Tektronix that retained information written on it without the need to refresh. Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ... Introduced about 1963, Teletype Corporations ASR33 was a very popular model of teleprinter. ... Template:A year The 1970s decade refers to the years from 1970 to 1979, inclusive. ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... Integrated circuit showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window showing the integrated circuit inside. ... Mostly obsolete, a storage tube is a special monochromatic CRT whose screen has a kind of memory (hence the name): when a portion of the screen is illuminated by the CRTs electron gun, it stays lit until a screen erase command is given. ... Tektronix is a United States corporation that is currently a major presence in the test, measurement, and measuring industry. ...

 A Televideo ASCII character mode terminal made around 1982
A Televideo ASCII character mode terminal made around 1982

Early video computer displays were sometimes nicknamed "Glass TTYs" and used individual logic gates, with no CPU. One of the motivations for development of the microprocessor was to simplify and reduce the electronics required in a terminal. Most terminals were connected to mainframe computers and often had a green or amber screen. Typically terminals communicate with the computer via a serial line, often using the RS-232 serial interface. IBM systems communicated over a coaxial cable using IBM's SNA protocol. Download high resolution version (1232x1059, 265 KB) A Televideo 925 computer terminal. ... Download high resolution version (1232x1059, 265 KB) A Televideo 925 computer terminal. ... There are 95 printable ASCII characters, numbered 32 to 126. ... A logic gate is an arrangement of electronically-controlled switches used to calculate operations in Boolean algebra. ... Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ... A microprocessor (sometimes abbreviated µP) is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... This article or section does not adequately cite its references or sources. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... International Business Machines Corporation (known as IBM or Big Blue; NYSE: IBM) is a multinational computer technology corporation headquartered in Armonk, New York, USA. The company is one of the few information technology companies with a continuous history dating back to the 19th century. ... Coaxial Cable Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, usually surrounded by a final insulating layer (Jacket). ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ...


Later, so called intelligent terminals were introduced, such as the VT52 and VT100 made by DEC, both of which are still widely emulated in software. These were called "intelligent" because they had the capability of interpreting escape sequences to position the cursor and control the display. Notable non-VT100 computer terminal types include the IBM 3270, various Wyse models (whose Wyse 60 was a best-seller—many are still in use), and the Tektronix 4014, but during the late 1970s there were dozens of manufacturers of terminals, many of which had incompatible command sequences. In the 1970s and early 1980s, the most common manufacturers were DEC, Wyse, Televideo, IBM, Lear-Siegler and Heath. The VT52 was a CRT-based computer terminal produced by Digital Equipment Corporation during the late 1970s. ... The VT100 was a video terminal made by Digital Equipment Corporation (DEC) which became the de facto standard used by terminal emulators. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... An escape sequence is a series of characters used to trigger some sort of command state in computers and their attached peripherals. ... A typical arrow-like mouse cursor. ... Clemson Universitys library catalog displayed in a 3270 emulation program The IBM 3270 is a class of terminals made by IBM since 1972 (known as Display Devices) normally used to communicate with IBM mainframes. ... Wyse is both the type of and the name of a manufacturer of computer terminals. ... The Tektronix 4014 was an early text and graphics computer terminal based on the companys own storage tube technology. ... 1970 (MCMLXX) was a common year starting on Thursday. ... Template:A year The 1970s decade refers to the years from 1970 to 1979, inclusive. ... The 1980s refers to the years of and between 1980 and 1989. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... Wyse is both the type of and the name of a manufacturer of computer terminals. ... A company that achieved its peak of success in the early 80s producing dumb terminals. ... International Business Machines Corporation (known as IBM or Big Blue; NYSE: IBM) is a multinational computer technology corporation headquartered in Armonk, New York, USA. The company is one of the few information technology companies with a continuous history dating back to the 19th century. ... There are very few or no other articles that link to this one. ... Heathkits were products of the Heath Company, Benton Harbor, Michigan. ...


While early IBM PCs had single color green screens, these were not terminals. The screen of a PC did not contain any character generation hardware; all video signals and video formatting was generated by the video display card in the PC. With suitable terminal software PCs could, however, emulate a terminal, if connected to a mainframe computer. Eventually microprocessor-based personal computers greatly reduced the market demand for terminals. Today, most PC telnet clients provide emulation of the most common terminal—the DEC VT100. IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... The IBM PC with green screen Green screen was the common name for a monochrome CRT computer display using a green P1 phosphor screen. ... TELNET (TELetype NETwork) is a network protocol used on the Internet or local area network (LAN) connections. ... The VT100 was a video terminal made by Digital Equipment Corporation (DEC) which became the de facto standard used by terminal emulators. ...


Graphical terminals

A HP T5700 thin client, with flash memory
A HP T5700 thin client, with flash memory

Most terminals today are GUI-based, and can show a picture on the screen. A graphical client typically uses a protocol like RDP for Microsoft Windows, or X11 for Unix-terminals. The bandwidth needed depends on the protocol used, the resolution, and the colour depth. Image File history File links Hpt5700. ... Image File history File links Hpt5700. ... A thin client, sometimes also called a lean client, is a computer (client) in client-server architecture networks which depends primarily on the central server for processing activities. ... GUI can refer to the following: GUI is short for graphical user interface, a term used to describe a type of interface in computing. ... RDP is an acronym that can stand for: Ribosomal Database Project Radiodifusão Portuguesa, subsidiary of Rádio e Televisão de Portugal Reconstruction and Development Programme, South Africas original post-Apartheid economic framework Reliable Datagram Protocol Remote Desktop Protocol Recreational Dive Planner Ratos de Porão, A Brazilian... In computing, the X Window System (commonly X11 or X) is a windowing system for bitmap displays. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®) is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ...


Graphical terminals have largely replaced text based ones and have led to renewed interest in thin clients. A Thin client is a computer (client) in client-server architecture networks which has little or no application logic, so it has to depend primarily on the central server for processing activities. ...


The X11 display system for Unix is built around a server/client architecture, and was one of the first possibilities for transporting graphical applications over a network, or later, the Internet.


Contemporary

Further information: Text terminal

Since the advent and subsequent popularization of the personal computer, few genuine hardware terminals are used to interface with computers today. Using the monitor and keyboard, modern operating systems like Linux and the BSD derivatives feature virtual consoles, which are mostly independent from the hardware used. A typical text terminal produces input and displays output and errors A text terminal or often just terminal (sometimes text console) is a serial computer interface for text entry and display. ... A computer display monitor, usually called simply a monitor when the meaning is clear from the context, is a piece of electrical equipment which displays viewable images generated by a computer without producing a permanent record. ... A computer keyboard is a peripheral partially modeled after the typewriter keyboard. ... Linux (IPA pronunciation: ) is a Unix-like computer operating system family. ... BSD redirects here; for other uses see BSD (disambiguation). ... First virtual console showing Knoppix boot messages In some operating systems such as Linux and FreeBSD, a virtual console (VC, sometimes virtual terminal, VT) is a conceptual combination of the keyboard and the display for a user interface. ...


When using a graphical user interface (or GUI) like the X Window System, one's display is typically occupied by a collection of windows associated with various applications, rather than a single stream of text associated with a single process. In this case, one may use a terminal emulator application within the windowing environment. This arrangement permits terminal-like interaction with the computer (for running a command line interpreter, for example) without the need for a physical terminal device. “PUI” redirects here. ... KDE 3. ... Apple Terminal. ... A command line interpreter is a computer program which reads lines of text that the user types and interprets them in the context of a given operating system or programming language. ...


Technical discussion

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 n last lines are visible. The input text is buffered until the Enter key is pressed, so the application receives a ready string of text. In this mode, the application needs not to know much about the terminal. In computing, a buffer is a region of memory used to temporarily hold output or input data, comparable to buffers in telecommunication. ... Originally, carriage return was the term for the key, lever, or mechanism on a typewriter that would cause the cylinder on which the paper was held (the carriage) to return to the left side of the paper after a line of text had been typed, and would often move it...


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 shells. GNU readline is a software library created and maintained by the GNU project. ... A command line interpreter is a computer program which reads lines of text that the user types and interprets them in the context of a given operating system or programming language. ...


Even more advanced interactivity 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). Notepad is the standard text editor for Microsoft Windows A text editor is a piece of computer software for editing plain text. ... A file manager is a computer program that provides a user interface to work with file systems. ... An example of a web browser (Mozilla Firefox), displaying the English Wikipedia main page. ... Box drawing characters are widely used in text user interfaces to draw various frames and boxes. ...


To achieve all this, the application must deal not only with plain text strings, but also with control characters and escape sequences, which allow to move cursor to an arbitrary position, to clear portions of the screen, change colors and display special characters — and also respond to function keys. In computing, a control character or non-printing character, is a code point (a number) in a character set that does not in itself represent a written symbol. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A typical arrow-like mouse cursor. ... A function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions. ...


The great problem here is that there are so 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. Unfortunately, the libraries, the databases and the terminal emulators themselves are too often buggy, so it is not unusual to see the display imperfect or garbled, or functional keys not working. Often it is necessary to hand-edit the terminfo definition to make a terminal emulator to work well. Perhaps the best overall results are obtained with xterm, because it is one of the most widely used terminal emulators. Apple Terminal. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Illustration of an application which may use libvorbisfile. ... Curses is a terminal control library for Unix-like systems, enabling the construction of text user interface (TUI) applications. ... xterm is the standard terminal emulator for the X Window System. ...


All this has led to little usability of many text-mode applications except when on console or in xterm. It has been suggested that Usability Requirements be merged into this article or section. ... The console is the text output device for system administration messages, particularly those from the BIOS or boot loader, the kernel, from the init system and from the system logger. ... xterm is the standard terminal emulator for the X Window System. ...


In recent years, the general switching of users to GUI has lessened the attention paid to terminal-handling libraries and to terminal emulation, and almost stalled the debugging efforts.


See also

  • Terminal server
  • IBM 3270 Classic corporate terminal for forms
  • HP 2640 microprocessor based terminal which combined serial ASCII with block mode forms and labeled function keys
  • Tektronix 4014 storage tube for vector graphics
  • VT100 for a classic ASCII ANSI-standard video terminal
  • Dumb terminal for a computer terminal that has limited functionality
  • Text terminal for the general concept of serial computer interface
  • Terminal emulator for an application program replacing a computer terminal
  • Virtual console for a concept that permits multiple terminals on one hardware
  • Computer console for a text output device for system administration messages
  • Remote Job Entry (RJE) a terminal used for the remote job submission, control, and printing
  • HASP A prominent IBM RJE terminal
  • IBM 2780 A prominent RJE terminal
  • IBM 3780 A prominent RJE terminal
  • TV Typewriter A very simple home-brew terminal that was used with early home computers

Historically, a terminal server was a device that attaches to serial RS-232 devices, such as green screen VT terminals or serial printers, and transports this traffic via TCP/IP TELNET, SSH or other vendor-specific protocol (i. ... Clemson Universitys library catalog displayed in a 3270 emulation program The IBM 3270 is a class of terminals made by IBM since 1972 (known as Display Devices) normally used to communicate with IBM mainframes. ... The HP2640 and other HP264X models were block-mode smart and intelligent terminals produced by Hewlett Packard using the new 8080 processor. ... The Tektronix 4014 was an early text and graphics computer terminal based on the companys own storage tube technology. ... The VT100 was a video terminal made by Digital Equipment Corporation (DEC) which became the de facto standard used by terminal emulators. ... It has been suggested that this article or section be merged into Data terminal. ... A typical text terminal produces input and displays output and errors A text terminal or often just terminal (sometimes text console) is a serial computer interface for text entry and display. ... Apple Terminal. ... A logo from Nintendos Virtual Console website Virtual Console ), sometimes abbreviated as VC, is a video game download service that is currently offered by Nintendo for its Wii gaming console. ... The console is the text output device for system administration messages, particularly those from the BIOS or boot loader, the kernel, from the init system and from the system logger. ... Mainframe computers support remote workstations that send files to and receive reports from the mainframe RJE system. ... The Houston Automated Spooling Program, commonly known as HASP, was developed by IBM Federal Systems Division contractors at the Johnson Space Center in Houston. ... The IBM 2780 and the IBM 3780 were devices developed by IBM to perform Remote Job Entry (RJE) functions. ... The IBM 2780 and the IBM 3780 were devices developed by IBM to perform Remote Job Entry (RJE) functions. ... The TV Typewriter (TVT) was an early computer kit, introduced by Don Lancaster in 1973. ...

External links

  • Terminal virus simulator - A tech demo that recreates the look of a corrupted dumb terminal; eye candy for veterans of older computer technology. Compatible with IBM-PC, its clones, or GP2X via DOSBox.

  Results from FactBites:
 
computer terminal — FactMonster.com (253 words)
Computer terminals vary greatly depending on the format of the data they handle.
Touch-sensitive terminals accept input made by touching a pressure-sensitive panel in front of a menu displayed on the screen.
computer graphics - computer graphics computer graphics, the transfer of pictorial data into and out of a computer.
JOB SPEC - REMOTE COMPUTER TERMINAL OPERATOR, JOB CODE 00470 (637 words)
The fundamental reason this classification exists is to operate a remote computer terminal in various departments throughout the City.
After initial training, the employee is expected to exercise some independent judgment in maintaining the routine flow of work.
One year of clerical experience involving the operation of computer data entry and retrieval equipment.
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