VT100

Last updated
VT100
DEC VT100 terminal.jpg
Manufacturer DEC
Type Computer terminal
Release date1978 (1978)
CPU Intel 8080
Memory3 KB RAM
8 KB ROM
175 byte NVRAM
Display12 in (30 cm) CRT
80x24 or 132x14 characters
SoundSpeaker (in keyboard)
Input83-key detachable keyboard
Connectivity RS-232 serial
(optional) 20 mA current loop
MassMonitor: 30 lb (14 kg)
Keyboard: 4.5 lb (2.0 kg)
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, which became the de facto standard for hardware video terminals and later terminal emulators.

Contents

The VT100 series, 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 equally successful. Ultimately, over six million terminals in the VT series were sold, based largely on the success of the VT100. [1]

Description

DEC's first video terminal was the VT05 (1970), succeeded by the VT50 (1974), and soon upgraded to the VT52 (1975). The VT52 featured a text display with 80 columns and 24 rows, bidirectional scrolling, and a custom control protocol 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 proprietary connections as in the case of systems like the IBM 3270, which generally required expensive controllers for distributed applications. In contrast, "dumb terminals" or "glass teletypes" like the ADM-3 (1975) lacked advanced features such as full cursor addressability, and competed mostly on lowest possible hardware cost.

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] : 1–3  The terminal provided an option for "smooth scrolling", whereby displayed lines of text were moved gradually up or down the screen to make room for new lines, instead of advancing in sudden "jumps". This made it easier to scan or read the text, although it somewhat slowed down the maximum data rate. [2] : 2–16 

The major internal change was the control protocol. Unlike the VT50/52's proprietary cursor control language, the VT100 was based on the newly emerging ANSI X3.64 standard for command codes. [a] At the time, some computer vendors[ who? ] had suggested that the new 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 offered greatly expanded capabilities, and the VT100 used the new Intel 8080 as its internal processor. [3] In addition, the VT100 provided backwards compatibility for VT52-compatible software, by also supporting the older control sequences. [4] Other improvements beyond the VT52 included a 132-column mode, and a variety of "graphic renditions" including blinking, bolding, reverse video, underlining, and lines of double-sized or double-width characters. The VT100 also introduced an additional box-drawing character set containing various pseudographics that allowed the drawing of on-screen forms.

All configuration 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 quickly dismantled into replaceable modules.

The VT100's internal layout can be split into two boards for functionality, not including the VT100's optional boards you can purchase. There is a board called the video monitor board which is used for things like adjusting the CRT on the terminal itself. This board is responsible for adjusting the CRT in the case that the electron beam is offset. [5] The terminal controller board is what handles the terminal logic, and includes a multitude of chips such as DEC's rebranding of the Intel 8080.

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

Options

The VT100 has various third party and first party boards designed to enhance the capabilities of the device. Most notable of these from DEC themselves are the VT1XX-AB (Advanced Video Option) and the VT1XX-AA (20 mA Current Loop Option). The cards' capabilities and existence are described in Chapter 4 of the VT100 User Guide. [4]

Variants

The VT101 was the lowest-cost member of the VT100 family. Vt100-adventure.jpg
The VT101 was the lowest-cost member of the VT100 family.
VT131 at the Living Computer Museum VT 131.jpg
VT131 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 character memory. The last option, known as the "Advanced Video Option" or AVO, allowed the terminal to support a full 24 lines of text in 132-column mode, increasing from the 14 lines of the unexpanded model when used in 132-column mode. The VT100 became a platform on which Digital constructed several related hardware 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 superimposed over 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 graphics commands to the terminal, rather than requiring the terminal to be set to a separate less-efficient graphics mode like the VT105.

The VT131 added block mode support, allowing a form to be sent to the terminal and filled in locally by the user, and then sending the contents of the fields in the form back to the host when the form is filled in. [7]

The VT100 form factor left significant physical space 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 16-bit LSI-11 microcomputer system within the case, [8] : pp65–72  and supported an optional dual TU58 DECtape II block-addressable cartridge tape drive [8] : pp73–80  which could be used like a very slow disk drive. The VT180 (codenamed "Robin") added a single-board microcomputer using a Zilog Z80 to run the CP/M operating system. The VT278 (DECmate) added a small PDP-8 processor, allowing the terminal to run Digital's WPS-8 word processing software.

See also

Related Research Articles

TECO, short for Text Editor & Corrector, is both a character-oriented text editor and a programming language, that was developed in 1962 for use on Digital Equipment Corporation computers, and has since become available on PCs and Unix. Dan Murphy developed TECO while a student at the Massachusetts Institute of Technology (MIT).

<span class="mw-page-title-main">Terminal emulator</span> Program that emulates a video terminal

A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term terminal covers all remote terminals, including graphical interfaces. A terminal emulator inside a graphical user interface is often called a terminal window.

<span class="mw-page-title-main">ANSI escape code</span> 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.

<span class="mw-page-title-main">Computer terminal</span> Computer input/output device for users

A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display bits and had to be connected to a terminal to print or input text through a keyboard. Teleprinters were used as early-day hard-copy terminals and predated the use of a computer screen by decades. The computer would typically transmit a line of data which would be printed on paper, and accept a line of data from a keyboard over a serial or other interface. Starting in the mid-1970s with microcomputers such as the Sphere 1, Sol-20, and Apple I, display circuitry and keyboards began to be integrated into personal and workstation computer systems, with the computer handling character generation and outputting to a CRT display such as a computer monitor or, sometimes, a consumer TV, but most larger computers continued to require terminals.

<span class="mw-page-title-main">VT220</span> Computer terminal from Digital Equipment Corporation

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 X.364. Among its major upgrades was a number of international character sets, as well as the ability to define new character sets.

Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a character set; at the same time, contrasted to graphics mode or other kinds of computer graphics modes.

ANSI.SYS is a device driver in the DOS family of operating systems that provides extra console functions through ANSI escape sequences. It is partially based upon a subset of the text terminal control standard proposed by the ANSI X3L2 Technical Committee on Codes and Character Sets.

xterm Standard terminal emulator for the X Window system

xterm is the standard terminal emulator for the X Window System. It allows users to run programs which require a command-line interface.

<span class="mw-page-title-main">VT52</span> CRT-based computer terminal by Digital

The VT50 is a CRT-based computer terminal that was 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.

<span class="mw-page-title-main">VT05</span> 1970 free-standing CRT terminal from Digital Equipment Corporation

The VT05 is the first free-standing CRT computer terminal from Digital Equipment Corporation introduced in 1970. Famous for its futuristic styling, the VT05 presents the user with an upper-case-only ASCII character display of 72 columns by 20 rows. The VT05 was a smart terminal that provides cursor addressing using a series of control characters, one of which allows 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.

<span class="mw-page-title-main">Rainbow 100</span> DEC microcomputer

The Rainbow 100 is a microcomputer introduced by Digital Equipment Corporation (DEC) in 1982. This desktop unit had a monitor similar to the VT220 and a dual-CPU box with both 4 MHz Zilog Z80 and 4.81 MHz Intel 8088 CPUs. The Rainbow 100 was a triple-use machine: VT100 mode, 8-bit CP/M mode, and CP/M-86 or MS-DOS mode using the 8088. It ultimately failed to succeed in the marketplace which became dominated by the simpler IBM PC and its clones which established the industry standard as compatibility with CP/M became less important than IBM PC compatibility. Writer David Ahl called it a disastrous foray into the personal computer market. The Rainbow was launched along with the similarly packaged DEC Professional and DECmate II which were also not successful. The failure of DEC to gain a significant foothold in the high-volume PC market would be the beginning of the end of the computer hardware industry in New England, as nearly all computer companies located there were focused on minicomputers for large organizations, from DEC to Data General, Wang, Prime, Computervision, Honeywell, and Symbolics Inc.

<span class="mw-page-title-main">VT420</span> Computer terminal from Digital Equipment Corporation

The VT420 is an ANSI standard computer terminal introduced in 1990 by Digital Equipment Corporation (DEC). The 420 is the only model in the 400 series, replacing the VT320. There are no color or graphics-capable 400 series terminals; the VT340 remained in production for those requiring ReGIS and Sixel graphics and color support. The entire lineup of VT300s and VT420 was eventually replaced by the relatively unknown VT500 series starting in 1993.

<span class="mw-page-title-main">Gold key (DEC)</span> Computer keyboard key

The Gold key is a computer keyboard key used as a prefix to invoke a variety of single-key editing and formatting functions. Usually located in the top-left position of the numeric keypad on platforms such as the VT100, it is the signature element of a consistent user interface implemented by Digital Equipment Corporation (DEC) across multiple product lines.

<span class="mw-page-title-main">VT520</span> 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, is a vector graphics markup language developed by Digital Equipment Corporation (DEC) for later models of their famous VT series of computer terminals. ReGIS supports rudimentary vector graphics consisting of lines, circular arcs, and similar shapes. Terminals supporting ReGIS generally allow graphics and text to be mixed on-screen, which makes the construction of graphs and charts relatively easy.

<span class="mw-page-title-main">VT320</span> Computer terminal from Digital Equipment Corporation

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

<span class="mw-page-title-main">Waveform graphics</span>

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.

The VT1000 was a monochrome X Window System computer terminal introduced by Digital Equipment Corporation (DEC) in April 1990. The VT1200 replaced the VT1000 later that year, consisting of a code update and a bump in the RAM from 1 to 2 MB. All of the VT1000 series communicated with their host computers over Ethernet, supporting TCP/IP as well as DEC's terminal-oriented Local Area Transport (LAT) protocol. They also included standard serial ports to allow basic terminal emulation, built into the ROM.

The Tektronix 4105 was a video terminal introduced by Tektronix in 1983. It could be used as a conventional text terminal supporting the ANSI escape codes of the VT102 or the VT52, as well as a graphics terminal using their own Tektronix 4010 series vector graphics. In graphics mode resolution was relatively limited, at 480 by 360 pixels, but it added a wide variety of new commands to the original 4010 set, including up to eight colors on the screen. The color commands would become a standard in their own right, and is supported by most terminal emulators supporting the Tek 4010 series.

References

  1. ↑ "VT 510/520 Video Display Terminal" (PDF). Boundless Technologies. Archived (PDF) from the original on 2015-02-05.
  2. 1 2 VT100 Series Technical Manual (PDF). Digital Equipment Corporation. 1979. Archived (PDF) from the original on 2020-01-01. Retrieved 2022-04-22.
  3. ↑ Shuford, Richard S. (2005), DEC Video Terminals—The VT100 and Its Successors, archived from the original on 2022-04-22, retrieved 2015-08-22
  4. 1 2 "VT100 User Guide". Digital Equipment Corporation. August 1978. EK-VT100-UG-001.
  5. ↑ VT101 Series Pocket Service Guide (PDF). Digital Equipment Corporation. September 1981. EK-VT101-PS-001.
  6. ↑ VT55 Programmer's Manual (PDF). Digital Equipment Corporation. February 1977. AA-4949A-TC. Archived (PDF) from the original on 2022-03-21. Retrieved 2022-04-21.
  7. ↑ VT131 Video Terminal User Guide (PDF) (2nd ed.). Digital Equipment Corporation. October 1981. EK-VT131-UG-002. Archived (PDF) from the original on 2022-07-11. Retrieved 2022-04-21.
  8. 1 2 VT103 LSI-11 Video Terminal User's Guide (PDF) (First ed.). Digital Equipment Corporation. September 1979. EK-VT103-UG-001. Archived (PDF) from the original on 2011-08-14. Retrieved 2014-05-03.
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.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.