Since the first introduction by Digital Equipment Corporation in 1978, VT100 proved to be successful due to its simplicity and extensibility. At the time when computers cost a fortune, low-cost terminals, that allow connecting to a single computer and sending/receiving data, was a great invention.
Basically, terminal consists of display and keyboard that are attached to server (mainframe) via serial port. The VT100 was succeeded by the VT101, VT102 and all other VTxxx series that added F-keys, editing keypad, character-set switching ability, multiple sessions, etc.
The main advantage of video terminals over their predecessors is the ability to position the cursor on the screen (thus allowing full-screen editing, forms-filling data entry, games, etc.) and to create special effects like highlighting, underlining, etc. Of course, all of these ideas carried over to the personal computers later on.
Advanced Serial Port Terminal provides software-based terminal emulation by generating the following control codes:
| "CTRL" + Key | Octal Code Transmitted | "CTRL" + Key | Octal Code Transmitted |
| Space Bar | 000 | P | 020 |
| A | 001 | Q | 021 |
| B | 002 | R | 022 |
| C | 003 | S | 023 |
| D | 004 | T | 024 |
| E | 005 | U | 025 |
| F | 006 | V | 026 |
| G | 007 | W | 027 |
| H | 010 | X | 030 |
| I | 011 | Y | 031 |
| J | 012 | Z | 032 |
| K | 013 | [ | 033 |
| L | 014 | \ | 034 |
| M | 015 | ] | 035 |
| N | 016 | ~ | 036 |
| O | 017 | ? | 037 |
| Cursor Key (Arrow) | ANSI Mode and Cursor Key Mode |
| Up | ESC [ A |
| Down | ESC [ B |
| Right | ESC [ C |
| Left | ESC [ D |