Video terminal: Difference between revisions
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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]] | 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]] process, instead of being printed on paper by a mechanical system. | ||
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. | 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 as early ones 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 go to specific screen locations was soon added, which made possible a predecessor of [[WYSIWYG]], to wit, [[screen editor]]s such as [[EMACS]]. | 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 editors|EMACS]]. | ||
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]]. | 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]]. | ||
Revision as of 12:09, 26 May 2018
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 terminals such as Teletypes, but with characters being 'painted' on a CRT via a purely electronic process, instead of being printed on paper by a mechanical system.
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 as early ones 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 go to specific screen locations was soon added, which made possible a predecessor of WYSIWYG, to wit, screen editors such as EMACS.
Once DRAM 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.
