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.
The VT100s, especially the VT102, was extremely successful in the market, and made DEC the leading terminal vendor. 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 would be sold, based largely on the success of the VT100s.
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 both due to their capabilities and their ability to be run over inexpensive serial links, rather than custom connection as in the case of systems like the IBM 3270 that generally required expensive controllers for distribution 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 speed selectable between 50 and 19,200 bit/s. Basic 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 disassembled quickly without use of tools.