VT220
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VT220

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VT220

The VT200 series is a family of computer terminals introduced by Digital Equipment Corporation (DEC) in November 1983. The VT220 was the basic version, a text-only version with multi-lingual capabilities. The VT240 added monochrome ReGIS vector graphics support to the base model, while the VT241 did the same in color. The 200 series replaced the successful VT100 series, providing more functionality in a much smaller unit with a much smaller and lighter keyboard. Like the VT100, the VT200 series implemented a large subset of ANSI X3.64. Among its major upgrades was a number of international character sets, as well as the ability to define new character sets.

The VT200 series was extremely successful in the market. Released at $1,295, but later priced at $795, the VT220 offered features, packaging and price that no other serial terminal could compete with at the time. In 1986, DEC shipped 165,000 units, giving them a 42% market share, double that of the closest competitor, Wyse. Competitors adapted by introducing similar models at lower prices, leading DEC to do the same by releasing the less-expensive $545 VT300 series in 1987. By that time, DEC had shipped over one million VT220s.

The VT220 improved on the earlier VT100 series of terminals with a redesigned keyboard, much smaller physical packaging, and a faster microprocessor, the Intel 8051 microcontroller. The VT220 was available with CRTs that used white, green, or amber phosphors.

The VT100s, like the VT50s before them, had been packaged in relatively large cases that provided room for expansion systems. The VT200s abandoned this concept, and wrapped the much smaller 1980s-era electronics tightly around the CRT. The result was a truncated pyramidal case with the apex at the back, only slightly larger than the CRT. This made it much easier to fit the terminal on a desk.

Normally the monitor sat facing upward at about a 15 degree angle. Because it was lower than head height, the result was an especially ergonomic terminal. On the rear bottom of the case was a carrying handle that could also be used to angle the monitor more forward. An extendable post could do so to even greater angles, allowing the monitor to face directly forward.

The LK201 keyboard supplied with the VT220 was one of the first full-length, low-profile keyboards available; it was developed at DEC's Roxbury, Massachusetts facility. It was much smaller and lighter than the VT100s version, and connected to the terminal using a lighter and more flexible coiled cable and a telephone jack connector.

The VT200s were the last DEC terminals to provide a 20mA current loop serial interface (using a 8-pin Molex-style connector), an older standard originally developed for the telegraph system but became popular on computers due to the early use of Teletype Model 33's as ad hoc terminals. A standard 25-pin D-connector was also provided for RS-232. Only one of the two ports could be in use at a given time. Later DEC terminals would replace both of these with their proprietary Modified Modular Jack (MMJ) connectors.

Another version of the terminal, the VT240, used DEC's own DEC T-11, a single-chip microcontroller version of the PDP-11 minicomputer. The VT241 is the color version of the VT240, consisting of the same V240 base unit with VR-241 color monitor. A VT240 can be upgraded to a VT241 by replacing the monitor and the cable.

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