Difference between revisions of "Video terminal"

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A '''video terminal''' was a device used to allow a [[user]] to do [[input/output]] to a computer; it usually communicated with the computer via [[asynchronous serial line]]. It was effectively roughly the same as the earlier [[printing terminal]]s such as [[Teletype]]s, but with characters being 'painted' on a [[cathode ray tube|CRT]] via a purely [[electronic]] proces, instead of being printed on paper by a mechanical system.
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A '''video terminal''' (sometimes called '''video display terminal''', or '''VDT''' for short) was a [[terminal]] on which the characters being output were 'painted' on a [[cathode ray tube|CRT]] via a purely [[electronic]] process. It was thus roughly the same functionality as the earlier [[printing terminal]]s, such as [[Teletype]]s, but instead of the output being printed on paper by a mechanical system, it was displayed on the screen. Like the earlier printing terminals, they were used to allow a [[user]] to do [[input/output]] to a computer; they usually communicated with the computer via [[asynchronous serial line]].  
  
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The original chief advantage was speed, since the all-electronic mechanism could run at much higher speeds; the disadvantage was that only a limited amount of information could be displayed at one time.
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The original chief advantage was speed, since the all-electronic mechanism could run at much higher speeds; the disadvantage was that only a limited amount of information could be displayed at one time. (This was particularly true of early ones, which could only display very limited amounts of text - some as small as 12 lines of 40 characters).
  
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Very early model provided only the same motion controls as their printing predecessors - line feed, carriage return, etc. However, the ability to go to specific screen locations was soon added, which made possible a predecessor of [[WYSIWYG]], to wit, [[screen editor]]s such as [[EMACS]].
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Very early model provided only the same motion controls as their printing predecessors - line feed, carriage return, etc. However, the ability to move the [[cursor]] to specific screen locations was soon added, which made possible a predecessor of [[WYSIWYG]], to wit, [[screen editor]]s such as [[Emacs editors|EMACS]].
  
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Once [[Dynamic RAM|DRAM]] prices fell low enough, they were replaced with [[bit-mapped display‏‎]]s, although the latter were directly connected to the computer's main [[bus]], usually on a [[personal computer]].
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A few had the capability to do [[graphics]], such as lines, points, etc.
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Once [[semiconductor]] [[Random Access Memory|RAM]] prices fell low enough, they were replaced with [[bit-mapped display‏‎]]s, although the latter were directly connected to the computer's main [[bus]], usually on a [[personal computer]].
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==See also==
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* [[:Category:Video Terminals|Video Terminals]]
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* [[flashterm]] - ANSI video terminal emulator
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==External links==
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* [https://vt100.net/ vt100.net]
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** [https://vt100.net/dec/vt_history Meet the Family] - a brief history of [[Digital Equipment Corporation|DEC]] VDT's
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** [https://vt100.net/dec/animation/ DEC Video Terminal Animations]
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[[Category: Device Basics‎‎]]

Latest revision as of 01:25, 21 February 2024

A video terminal (sometimes called video display terminal, or VDT for short) was a terminal on which the characters being output were 'painted' on a CRT via a purely electronic process. It was thus roughly the same functionality as the earlier printing terminals, such as Teletypes, but instead of the output being printed on paper by a mechanical system, it was displayed on the screen. Like the earlier printing terminals, they were used to allow a user to do input/output to a computer; they usually communicated with the computer via asynchronous serial line.

The original chief advantage was speed, since the all-electronic mechanism could run at much higher speeds; the disadvantage was that only a limited amount of information could be displayed at one time. (This was particularly true of early ones, which could only display very limited amounts of text - some as small as 12 lines of 40 characters).

Very early model provided only the same motion controls as their printing predecessors - line feed, carriage return, etc. However, the ability to move the cursor to specific screen locations was soon added, which made possible a predecessor of WYSIWYG, to wit, screen editors such as EMACS.

A few had the capability to do graphics, such as lines, points, etc.

Once semiconductor RAM prices fell low enough, they were replaced with bit-mapped display‏‎s, although the latter were directly connected to the computer's main bus, usually on a personal computer.

See also

External links

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