It was introduced in August 1978, following its predecessor, the VT52, and communicated with its host system over serial lines using the ASCII character set and control sequences (a.k.a. escape sequences) standardized by ANSI. The VT100 was also the first Digital mass-market terminal to incorporate "graphic renditions" (blinking, bolding, reverse video, and underlining) as well as a selectable 80 or 132 column display. 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. The VT100 also introduced an additional character set that allowed the drawing of on-screen forms.
The control sequences used by the VT100 family are based on the ANSI X3.64 standard, also known as ECMA-48 and ISO/IEC 6429. These are sometimes referred to as ANSI escape codes. The VT100 was not the first terminal to be based on X3.64—The Heath Company had a microprocessor-based video terminal, the Heathkit H-19 (H19), that implemented a subset of the standard proposed by ANSI in X3.64. In addition, the VT100 provided backwards compatibility for VT52 users, with support for the VT52 control sequences.
In 1983, the VT100 was replaced by the more-powerful VT200 series terminals such as the VT220.
The VT100 was also the first of Digital's terminals to be based upon an industry-standard microprocessor (in this case, the Intel 8080). Options could be added to the terminal to support an external printer, additional graphic renditions, and more memory (the "AVO" 'Advanced' Video Option — without this option, the VT100 could not display a full 24 lines of text when in 132 column mode). The VT100 became a platform on which Digital constructed related products.
The VT101 and VT102 were cost-reduced non-expandable follow-on products, with the VT102 including the AVO and serial printer port options of the VT100. The VT105 contained a simple graphics subsystem mostly-compatible with the earlier VT55. The VT125 added an implementation of the byte-efficient Remote Graphic Instruction Set (ReGIS.) The VT103 includes a cardcage and 4×4 (8-slot) Q-Bus backplane, sufficient to configure a small LSI-11 system within the terminal case,:pp65–72 and supports an optional dual TU58 DECtape II block addressable cartridge tape drive :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.
- Shuford, Richard S. (2005), DEC Video Terminals—The VT100 and Its Successors, retrieved 2012-12-08
- VT103 LSI-11 Video Terminal User's Guide (Digital Equipment Corporation, 1979)
- DEC video terminal history
- VT100 user guide
- VT100 Series Technical Manual
- The DEC category at the Terminals Wiki