In the context of
telecommunicationTelecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s, a
terminal is a device which is capable of communicating over a line. Examples of terminals are
telephoneThe telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
s, fax machines, and network devices - printers and workstations.
The
mobile data terminal (MDT)A mobile data terminal is a computerized device used in public transit vehicles, taxicabs, courier vehicles, service trucks, commercial trucking fleets, military logistics, fishing fleets, warehouse inventory control, and emergency vehicles to communicate with a central dispatch office...
is a device used in the field of
telematicsTelematics typically is any integrated use of telecommunications and informatics, also known as ICT...
.
Emulation of terminals by computer programs
Many computers use a serial access program to communicate with other computers via
telephone lineA telephone line or telephone circuit is a single-user circuit on a telephone communication system...
or serial device, thus emulating a
computer terminalA 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...
. HyperTerminal is a widely distributed
terminal emulatorA terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
.
When the first
MacintoshThe Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
was released, a program called
MacTerminalMacTerminal was the first telecommunications and terminal emulation application software program available for Mac OS. MacTerminal enabled users to connect via modem or serial port to bulletin board systems and online services , and to other computers...
was used to communicate with many computers, including the
IBM PCThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
.
Dec Terminal was one of the first Terminal programs for the popular
AltairThe MITS Altair 8800 was a microcomputer design from 1975 based on the Intel 8080 CPU and sold by mail order through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers hoped to sell only a few hundred build-it-yourself kits to hobbyists, and were...
.
Modes
Terminals can operate in various modes, relating to when they send input typed by the user on the keyboard to the receiving system (whatever that may be):
character mode (a.k.a. character-at-a-time mode)
- In this mode, typed input is sent immediately to the receiving system.
line mode (a.k.a. line-at-a-time mode)
- In this mode, the terminal provides a local line editing function, and sends an entire input line, after it has been locally edited, when the user presses a key. A so-called line mode terminal operates solely in this mode.
block mode (a.k.a. screen-at-a-time mode)
- In this mode, the terminal provides a local full-screen data function. The user can enter input into multiple fields in a form on the screen (defined to the terminal by the receiving system), moving the cursor around the screen using keys such as
{{Other uses|Terminal (disambiguation)}}
{{more sources|date=January 2011}}
In the context of telecommunicationTelecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s, a terminal is a device which is capable of communicating over a line. Examples of terminals are telephoneThe telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
s, fax machines, and network devices - printers and workstations.
The mobile data terminal (MDT)A mobile data terminal is a computerized device used in public transit vehicles, taxicabs, courier vehicles, service trucks, commercial trucking fleets, military logistics, fishing fleets, warehouse inventory control, and emergency vehicles to communicate with a central dispatch office...
is a device used in the field of telematicsTelematics typically is any integrated use of telecommunications and informatics, also known as ICT...
.
Emulation of terminals by computer programs
{{main|terminal emulator}}
Many computers use a serial access program to communicate with other computers via telephone lineA telephone line or telephone circuit is a single-user circuit on a telephone communication system...
or serial device, thus emulating a computer terminalA 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...
. HyperTerminal is a widely distributed terminal emulatorA terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
.
When the first MacintoshThe Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
was released, a program called MacTerminalMacTerminal was the first telecommunications and terminal emulation application software program available for Mac OS. MacTerminal enabled users to connect via modem or serial port to bulletin board systems and online services , and to other computers...
was used to communicate with many computers, including the IBM PCThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
.
Dec Terminal was one of the first Terminal programs for the popular AltairThe MITS Altair 8800 was a microcomputer design from 1975 based on the Intel 8080 CPU and sold by mail order through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers hoped to sell only a few hundred build-it-yourself kits to hobbyists, and were...
.
Modes
{{further|terminal intelligence}}
Terminals can operate in various modes, relating to when they send input typed by the user on the keyboard to the receiving system (whatever that may be):
character mode (a.k.a. character-at-a-time mode)
- In this mode, typed input is sent immediately to the receiving system.{{sfn|Bolthouse|1996|p=18}}
line mode (a.k.a. line-at-a-time mode)
- In this mode, the terminal provides a local line editing function, and sends an entire input line, after it has been locally edited, when the user presses a {{keypress|return}} key.{{sfn|Bolthouse|1996|p=18}} A so-called line mode terminal operates solely in this mode.{{sfn|Bangia|2010|p=324}}
block mode (a.k.a. screen-at-a-time mode)
- In this mode, the terminal provides a local full-screen data function. The user can enter input into multiple fields in a form on the screen (defined to the terminal by the receiving system), moving the cursor around the screen using keys such as
{{Other uses|Terminal (disambiguation)}}
{{more sources|date=January 2011}}
In the context of telecommunicationTelecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s, a terminal is a device which is capable of communicating over a line. Examples of terminals are telephoneThe telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
s, fax machines, and network devices - printers and workstations.
The mobile data terminal (MDT)A mobile data terminal is a computerized device used in public transit vehicles, taxicabs, courier vehicles, service trucks, commercial trucking fleets, military logistics, fishing fleets, warehouse inventory control, and emergency vehicles to communicate with a central dispatch office...
is a device used in the field of telematicsTelematics typically is any integrated use of telecommunications and informatics, also known as ICT...
.
Emulation of terminals by computer programs
{{main|terminal emulator}}
Many computers use a serial access program to communicate with other computers via telephone lineA telephone line or telephone circuit is a single-user circuit on a telephone communication system...
or serial device, thus emulating a computer terminalA 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...
. HyperTerminal is a widely distributed terminal emulatorA terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
.
When the first MacintoshThe Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
was released, a program called MacTerminalMacTerminal was the first telecommunications and terminal emulation application software program available for Mac OS. MacTerminal enabled users to connect via modem or serial port to bulletin board systems and online services , and to other computers...
was used to communicate with many computers, including the IBM PCThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
.
Dec Terminal was one of the first Terminal programs for the popular AltairThe MITS Altair 8800 was a microcomputer design from 1975 based on the Intel 8080 CPU and sold by mail order through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers hoped to sell only a few hundred build-it-yourself kits to hobbyists, and were...
.
Modes
{{further|terminal intelligence}}
Terminals can operate in various modes, relating to when they send input typed by the user on the keyboard to the receiving system (whatever that may be):
character mode (a.k.a. character-at-a-time mode)
- In this mode, typed input is sent immediately to the receiving system.{{sfn|Bolthouse|1996|p=18}}
line mode (a.k.a. line-at-a-time mode)
- In this mode, the terminal provides a local line editing function, and sends an entire input line, after it has been locally edited, when the user presses a {{keypress|return}} key.{{sfn|Bolthouse|1996|p=18}} A so-called line mode terminal operates solely in this mode.{{sfn|Bangia|2010|p=324}}
block mode (a.k.a. screen-at-a-time mode)
- In this mode, the terminal provides a local full-screen data function. The user can enter input into multiple fields in a form on the screen (defined to the terminal by the receiving system), moving the cursor around the screen using keys such as {{keypress
Tab key on a keyboard is used to advance the cursor to the next tab stop.- Origin :The word tab derives from the word tabulate, which means "to arrange data in a tabular, or table, form"...
and the arrow keys and performing editing functions locally using {{keypressThe Insert key is a key commonly found on computer keyboards.It is primarily used to switch between the two text-entering modes on a personal computer or word processor. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present on and after its current...
, {{keypressThe delete key , known less ambiguously as forward delete, performs a function when struck on a computer keyboard during text or command editing, which is to discard the character ahead of the cursor's position, moving all following characters one position "back" towards the freed letterspace. The...
, {{keypress and so forth. The terminal only sends the completed form, comprising all of the data on the screen, to the receiving system when the user presses an {{keypress|enter}} key.{{sfn|Diercks|2002|p=2}}{{sfn|Gofton|1991|p=73}}{{sfn|Bolthouse|1996|p=18}}
Note the distinction between the {{keypress and the {{keypressIn computer keyboards, the enter key in most cases causes a command line, window form, or dialog box to operate its default function...
keys. In some multiple-mode terminals, that can switch between modes, pressing the {{keypress|enter}} key when not in block mode does not do the same thing as pressing the {{keypress|return}} key. Whilst the {{keypress|return}} key will cause an input line to be sent to the host in line-at-a-time mode, the {{keypress|enter}} key will rather cause the terminal to transmit the contents of the character row where the cursor is currently positioned to the host, host-issued prompts and all.{{sfn|Diercks|2002|p=2}}
Different computer operating systemAn operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s require different degrees of mode support when terminals are used as computer terminalA 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...
s. The POSIX terminal interfaceThe POSIX terminal interface is the generalized abstraction, comprising both an Application Programming Interface for programs, and a set of behavioural expectations for users of a terminal, as defined by the POSIX standard and the Single Unix Specification...
, as provided by Unix and POSIX-compliant operating systems, does not accommodate block-mode terminals at all, and only rarely requires the terminal itself to be in line-at-a-time mode, since the operating system is required to provide canonical input mode, where the terminal device driver in the operating system emulates local echo in the terminal, and performs line editing functions at the host end. Most usually, and especially so that the host system can support non-canonical input mode, terminals for POSIX-compliant systems are always in character-at-a-time mode. In contrast, IBM 3270The IBM 3270 is a class of block oriented terminals made by IBM since 1972 normally used to communicate with IBM mainframes. As such, it was the successor to the IBM 2260 display terminal. Due to the text colour on the original models, these terminals are informally known as green screen terminals...
terminals connected to MVSMultiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers...
systems are always required to be in block mode.{{sfn|Raymond|2004|p=72}}{{sfn|Burgess|1988|p=127}}{{sfn|Topham|1990|p=77}}{{sfn|Rodgers|1990|p=88–90}}
External links
{{telecomm-stub}}