Editing Computer terminal (section)

===Intelligent terminals{{anchor|Intelligent terminal|"Intelligent" terminals}}===
An '''intelligent terminal'''<ref>{{cite web |title=intelligent terminal Definition from PC Magazine Encyclopedia |url=https://www.pcmag.com/encyclopedia/term/45110/intelligent-terminal}}</ref> does its own processing, usually implying 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.<ref>Twentieth Century Words; by John Ayto; Oxford Unity Press; page 413</ref>

Notable examples include the [[IBM 2250]], predecessor to the IBM 3250 and IBM 5080, and [[IBM 2260]],<ref name=Chicken.egg>{{cite web |title=What is 3270 (Information Display System) |url=https://whatis.techtarget.com/definition/3270-Information-Display-System |quote=3270 .. over its predecessor, the 2260}}</ref> predecessor to the [[IBM 3270]], introduced with [[IBM System/360|System/360]] in 1964.
[[File:HypertextEditingSystemConsoleBrownUniv1969.jpg|thumb|right|IBM 2250 Model 4, including [[light pen]] and programmed function keyboard]]Most terminals were connected to [[minicomputer]]s or [[mainframe computer]]s and often had a green or amber screen. Typically terminals communicate with the computer via a [[serial port]] via a [[null modem]] cable, often using an [[Electronic Industries Alliance|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 [[Systems Network Architecture|SNA]] protocol, but for many DEC, Data General and [[NCR Corporation|NCR]] (and so on) computers there were many visual display suppliers competing against 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 [[VT100|DEC VT100]] (1978), the user and programmer could notice significant advantages in VDU technology improvements, yet not all programmers used 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 board]]s with many [[integrated circuit]]s; the single factor that classed 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 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 (network)|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 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 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 such as the TeleVideo TS-800 could run [[CP/M-86]], blurring the distinction between terminal and Personal Computer.

Another of the motivations for development of the [[microprocessor]] was to simplify and reduce the electronics required in a terminal. That also made it practicable to load several "personalities" into a single terminal, so a Qume QVT-102 could emulate many popular terminals of the day, and so be sold into organizations that did not wish to make any software changes. Frequently emulated terminal types included:
* [[Lear Siegler]] [[ADM-3A]] and later models
* [[TeleVideo]] 910 to 950 (these models copied ADM3 codes and added several of their own, eventually being copied by Qume and others)
* Digital Equipment Corporation [[VT52]] and [[VT100]]
* [[Data General]] D1 to D3 and especially D200 and D210
* [[Hazeltine Corporation]] H1500
* [[Tektronix]] [[Tektronix 4014|4014]]
* [[Wyse]] W50, W60 and W99

The [[ANSI X3.64]] escape code standard produced uniformity to some extent, but significant differences remained. For example, the [[VT100]], [[Heathkit]] H19 in ANSI mode, Televideo 970, Data General D460, and [[Qume]] QVT-108 terminals all followed the ANSI standard, yet differences might exist in codes from [[function key]]s, what character attributes were available, block-sending of fields within forms, "foreign" character facilities, and handling of printers connected to the back of the screen.

In the 21st century, 
the term ''Intelligent Terminal'' can now refer to a retail [[Point of Sale]] computer.<ref>{{cite web |title=Epson TM-T88V-DT Intelligent Terminal, 16GB SSD, LE, Linux, ... |url=https://www.epson.de/en/viewcon/corporatesite/products/mainunits/overview/13350 |quote=Retailers can .. reduce costs with .. Epson TM-T88V-DT ... a unique integrated terminal}}</ref>