VT100

Last updated
VT100
DEC VT100 terminal.jpg
Manufacturer DEC
Type Computer terminal
Release date1978 (1978)
CPU Intel 8080
Display CRT 80x24 characters
Input Computer keyboard
Connectivityserial lines
Predecessor VT50
Successor VT220

The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation (DEC). It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, and added a number of extended codes for special features like controlling the status lights on the keyboard. This led to rapid uptake of the ANSI standard, becoming the de facto standard for terminal emulators.

Contents

The VT100s, especially the VT102, was extremely successful in the market, and made DEC the leading terminal vendor at the time. The VT100 series was replaced by the VT200 series starting in 1983, which proved just as successful. Ultimately, over six million terminals in the VT series were sold, based largely on the success of the VT100s. [1]

Description

DEC's first successful video terminal was the VT50, introduced in 1974 and quickly replaced by the VT52 in 1975. The VT52 featured a text display with 80 columns and 24 rows, bidirectional scrolling, and a custom control language that allowed the cursor to be moved about the screen. These "smart terminals" were a hit due both to their capabilities and to their ability to be run over inexpensive serial links, rather than custom connection as in the case of systems like the IBM 3270, which generally required expensive controllers for distributed applications.

The VT100 was introduced in August 1978, replacing the VT50/VT52 family. Like the earlier models, it communicated with its host system over serial lines at a minimum speed of 50 bit/s, but increased the maximum speed to 19,200 bit/s, double that of the VT52. [2] The terminal provided an option for smooth scrolling, where existing lines of text were moved slowly up or down the screen to make room for new lines, instead of "jumping". This made it easier to read the text, although it slowed down the maximum data rate. [3]

The major change within the system was the control system. Unlike the VT50/52's proprietary cursor control language, the VT100 was based on the emerging ANSI X3.64 standard for command codes. [lower-alpha 1] At the time, computer vendors suggested that the standard was beyond the state of the art and could not be implemented at a reasonable price. The introduction of low-cost microprocessors and the ever-falling cost of computer memory addressed these problems, and the VT100 used the new Intel 8080 as its internal processor. [4] In addition, the VT100 provided backwards compatibility for VT52 users, with support for the VT52 control sequences. [5]

Other improvements on the VT52 included a 132 column mode, and a variety of "graphic renditions" including blinking, bolding, reverse video, and underlining. The VT100 also introduced an additional box-drawing character set containing various pseudographics that allowed the drawing of on-screen forms. All setup of the VT100 was accomplished using interactive displays presented on the screen; the setup data was stored in non-volatile memory within the terminal. Maintainability was also significantly improved since a VT100 could be dismantled quickly without tools.

In 1983, the VT100 was replaced by the more powerful VT200 series terminals such as the VT220.

Variants

VT101 Vt100-adventure.jpg
VT101
VT131 on display at the Living Computer Museum VT 131.jpg
VT131 on display at the Living Computer Museum

The VT100 was the first of Digital's terminals to be based on an industry-standard microprocessor, the Intel 8080. Options could be added to the terminal to support an external printer, additional graphic renditions, and more memory. The later option, known as Advanced Video Option or AVO, allowed the terminal to support a full 24 lines of text in 132 column mode, increasing it from the 14 lines of the un-expanded model. The VT100 became a platform on which Digital constructed related products.

The VT101 and VT102 were cost-reduced, non-expandable follow-on versions. The VT101 was essentially a base-model VT100, while the VT102 came standard with the AVO and serial printer port options pre-installed. The VT105 contained a simple graphics subsystem known as waveform graphics which was mostly compatible with same system in the earlier VT55. This system allowed two mathematical functions to be drawn to the screen on top of the normal text display, allowing text and graphics to be mixed to produce charts and similar output. [6] The VT125 added an implementation of the byte-efficient Remote Graphic Instruction Set, ReGIS, which used custom ANSI codes to send the graphics commands to the terminal, rather than requiring the terminal to be set to a separate graphics mode like the VT105.

The VT100 form factor left significant room in the case for expansion, and DEC used this to produce several all-in-one stand-alone minicomputer systems. The VT103 included a cardcage and 4×4 (8-slot) Q-Bus backplane, sufficient to configure a small LSI-11 system within the case, [7] :pp65–72 and supported an optional dual TU58 DECtape II block addressable cartridge tape drive [7] :pp73–80 which behaves like a very slow disk drive. The VT180 (codenamed "Robin") added a single-board microcomputer using a Zilog Z80 to run CP/M. The VT278 (DECmate) added a PDP-8 processor, allowing the terminal to run Digital's WPS-8 word processing software.

See also

Related Research Articles

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Terminal emulator Program that emulates a video terminal

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In computer science, an escape sequence is a combination of characters that has a meaning other than the literal characters contained therein; it is marked by one or more preceding characters.

ANSI escape code Method used for display options on video text terminals

ANSI escape sequences are a standard for in-band signaling to control cursor location, color, font styling, and other options on video text terminals and terminal emulators. Certain sequences of bytes, most starting with an ASCII escape character and a bracket character, are embedded into text. The terminal interprets these sequences as commands, rather than text to display verbatim.

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The Multinational Character Set is a character encoding created in 1983 by Digital Equipment Corporation (DEC) for use in the popular VT220 terminal. It was an 8-bit extension of ASCII that added accented characters, currency symbols, and other character glyphs missing from 7-bit ASCII. It is only one of the code pages implemented for the VT220 National Replacement Character Set (NRCS). MCS is registered as IBM code page/CCSID 1100 since 1992. Depending on associated sorting Oracle calls it WE8DEC, N8DEC, DK8DEC, S8DEC, or SF8DEC.

VT220 Computer terminal from Digital Equipment Corporation

The VT220 is a computer terminal introduced by Digital Equipment Corporation (DEC) in November 1983. 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 X.364. Among its major upgrades was a number of international character sets, as well as the ability to define new character sets.

Text-based user interface Type of interface based on outputting to or controlling a text display

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VT52 CRT-based computer terminal

The VT50 was a CRT-based computer terminal introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forward-only scrolling based on the earlier VT05. DEC documentation of the era refers to the terminals as the DECscope, a name that was otherwise almost never seen.

VT05 1970 free-standing CRT terminal from Digital Equipment Corporation

The VT05 was the first free-standing CRT computer terminal from Digital Equipment Corporation introduced in 1970. Famous for its futuristic styling, the VT05 presented the user with an upper-case only ASCII character display of 20 rows by 72 columns. The VT05 was a smart terminal that provided cursor addressing using a series of control characters, one of which allowed the cursor to be positioned at an absolute location on the screen. This basic system provided the basis of similar systems in the later and greatly improved VT50 and VT52 series.

WPS-8 is a Word Processing System sold by Digital Equipment Corporation for use with their PDP-8 processors.

HP 2640

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VT420 Computer terminal from Digital Equipment Corporation

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The ADM-3A was an influential early video display terminal, introduced in 1976. It was manufactured by Lear Siegler and had a 12-inch screen displaying 12 or 24 lines of 80 characters. It set a new industry low single unit price of $995. Its "dumb terminal" nickname came from some of the original trade publication advertisements. It quickly became commercially successful because of the rapid increase of computer communications speeds, and because of new minicomputer systems released to the market which required inexpensive operator consoles.

Sixel

Sixel, short for "six pixels", is a bitmap graphics format supported by terminals and printers from DEC. It consists of a pattern six pixels high and one wide, resulting in 64 possible patterns. Each possible pattern is assigned an ASCII character, making the sixels easy to transmit on 7-bit serial links.

VT520 Computer terminal from Digital Equipment Corporation

The VT520 is an ANSI standard computer terminal introduced by Digital Equipment Corporation (DEC) in 1993 and 1994. The VT520 is a multi-session monochrome text-only terminal with a built-in 14" monitor. The VT510 was a single-session version, while the VT525 added color support and used a separate external monitor.

ReGIS, short for Remote Graphic Instruction Set, was a vector graphics markup language developed by Digital Equipment Corporation (DEC) for later models of their famous VT series of computer terminals. ReGIS supported rudimentary vector graphics consisting of lines, circular arcs, and similar shapes. Terminals supporting ReGIS generally allowed graphics and text to be mixed on-screen, which made construction of graphs and charts relatively easy.

VT320 Computer terminal from Digital Equipment Corporation

The VT320 was an ANSI standard computer terminal introduced by Digital Equipment Corporation (DEC) in 1987. The VT320 was the text-only version, while the VT330 added monochrome ReGIS, Sixel and Tektronix 4010 graphics, and the VT340 added color.

Waveform graphics

Waveform graphics is a simple vector graphics system introduced by Digital Equipment Corporation (DEC) on the VT55 and VT105 terminals in the mid-1970s. It was used to produce graphics output from mainframes and minicomputers. DEC used the term "waveform graphics" to refer specifically to the hardware, but it was used more generally to describe the whole system.

References

  1. "VT 510/520 Video Display Terminal", Boundless Technologies.
  2. Digital Equipment Corporation (1979), VT100 Series Technical Manual (PDF), pp. 1–3, retrieved 2015-08-22
  3. Digital Equipment Corporation (1979), VT100 Series Technical Manual (PDF), pp. 2–13, retrieved 2021-10-12
  4. Shuford, Richard S. (2005), DEC Video TerminalsThe VT100 and Its Successors , retrieved 2015-08-22
  5. http://ascii-table.com/ansi-escape-sequences-vt-100.php
  6. VT55 Programmer's Manual, DEC, 1977
  7. 1 2 VT103 LSI-11 Video Terminal User's Guide (Digital Equipment Corporation, 1979)
Notes
  1. A similar standard was being organized as ECMA-48, which was fairly similar to X3.64. The two standards were later merged in ISO 6429.