VT100
| Industry | Computer hardware |
|---|---|
| Founded | November 7, 1957 |
| Headquarters | Maynard , United States |
| Products | VT100 series computer terminals |
The VT100 is a video computer terminal launched by Digital Equipment Corporation (DEC) in August 1978. It was among the pioneers in implementing ANSI escape codes for cursor positioning and additional functionalities, incorporating extended codes for features such as keyboard indicator lights. This innovation significantly contributed to the widespread acceptance of the ANSI standard, which eventually became the de facto standard for hardware terminals and later terminal emulator software.
The VT100 series, particularly the VT102 model, achieved remarkable commercial success, solidifying DEC's position as a dominant terminal manufacturer. It was followed by the highly regarded VT220 in 1983. Sales of VT series terminals surpassed six million units, largely propelled by the influence of the VT100.
Description
DEC's early video terminal lineup began with the VT05 in 1970, succeeded by the VT50 in 1974 and the VT52 in 1975. The VT52 offered an 80×24 character display, supported bidirectional scrolling, and utilized a proprietary cursor control protocol. These "smart terminals" gained popularity due to their feature set and compatibility with affordable serial connections, contrasting with costly proprietary systems like the IBM 3270. Conversely, simpler "dumb terminals" such as the ADM-3 (introduced in 1975) competed primarily on price without advanced capabilities.
Introduced in 1978 to replace the VT50/VT52 models, the VT100 communicated via serial lines at speeds up to 19,200 bits per second—twice that of its predecessors. It optionally featured "smooth scrolling," which enhanced readability by gradually shifting text on the display but reduced maximum data throughput.
A major advancement was its adoption of the emerging ANSI X3.64 standard for control sequences instead of using proprietary protocols. Although initially doubted due to concerns about feasibility and cost, improvements in microprocessor technology and memory enabled DEC to implement ANSI compliance using the Intel 8080 CPU. The VT100 also preserved backward compatibility with VT52 command sequences.
Additional features included a 132-column display mode and various text attributes such as blinking, boldface, reverse video, underlining, and double-height or double-width characters. It introduced a box-drawing character set that facilitated on-screen form creation.
Configuration was handled through interactive on-screen menus, with preferences saved in non-volatile memory. Its modular construction simplified maintenance by allowing easy replacement of components.
Internally, the VT100 consisted of a video monitor board responsible for CRT controls and a terminal controller board managing logic operations, incorporating an Intel 8080 processor rebranded by DEC.
In 1983, DEC succeeded the VT100 with more advanced models from the VT200 series like the VT220, maintaining its leadership in computer terminal markets.
Options
The VT100 supports a range of expansion boards from both DEC and third-party manufacturers, including notable options such as DEC's VT1XX-AB (Advanced Video Option) and VT1XX-AA (20 mA Current Loop Option). These expansions enhance terminal functionality as outlined in the VT100 User Guide.
Variants
As Digital’s first terminal built around the industry-standard Intel 8080 microprocessor, the VT100 offered expansion options including external printer support, enhanced graphics capabilities, and increased character memory capacity. The Advanced Video Option (AVO) allowed for displaying 24 lines of text in 132-column mode instead of just 14 lines available on the base model. This platform served as a foundation for several related hardware products.
Lower-cost, non-expandable variants included the VT101—a basic version of the VT100—and the VT102, which came equipped with AVO and a serial printer port by default. The VT105 incorporated simple waveform graphics compatible with those of the earlier VT55, enabling combined text and graphical output suitable for charting. The VT125 introduced an efficient Remote Graphic Instruction Set (ReGIS) that utilized custom ANSI codes to render graphics without switching modes.
The VT131 added support for block mode operation, allowing forms to be transmitted to the terminal for local completion and then returning field data back to the host system.
DEC leveraged the ample chassis space of the VT100 design to develop integrated minicomputer systems. The VT103 featured an 8-slot Q-Bus backplane capable of housing a 16-bit LSI-11 microcomputer system and offered an optional dual TU58 DECtape II cartridge drive providing block-addressable storage. The VT180 ("Robin") incorporated a Zilog Z80 single-board computer running CP/M, while the VT278 (DECmate) embedded a PDP-8 processor designed to run Digital’s WPS-8 word processing software.
See also
References
- Notes
External links
- History of DEC video terminals Archived version
- User guide for the VT100
- Technical manual for the VT100 series
- ECMA-48 standard documentation
- The DEC section on the Terminals Wiki