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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →The DEC VT220 is a physical serial terminal: a monochrome monitor/system unit and a separate keyboard that communicate with a host over serial interfaces. It displays 24 rows in either 80- or 132-column mode, supports documented EIA RS-232C and 20 mA host connections, and offers VT200, VT100, and VT52 operating modes. Those details—not just its CRT appearance—are what make it a proper terminal.
What makes the DEC VT220 a proper serial terminal?
Digital Equipment Corporation describes the VT220 as a general-purpose video display terminal using ANSI standard functions. Unlike a modern all-in-one computer, it is a display-and-keyboard device designed to exchange data with a separate host. In online operation, keyboard input goes to the host, and data received from the host appears on the screen.
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Monitor, keyboard, and display
The VT220 consists of a monitor/system unit and a separate keyboard. Its monochrome display has 24 rows and can be configured for 80 or 132 columns. The programmer reference manual specifies 800 × 240 pixels in 80-column mode and 1188 × 240 pixels in 132-column mode. It also documents five 94-character sets, including the DEC multinational character set, downloadable character sets, user-definable function keys, and text treatments such as reverse video, underline, bold, blinking, and double-height or double-width lines. (Digital Equipment Corporation, VT220 Programmer Reference Manual)
Serial interfaces and communication
The manual documents asynchronous communications at rates up to 19.2 kbit/s, an EIA RS-232C host port, a 20 mA host port, and an EIA RS-232C printer port. It lists both 7-bit and 8-bit character formats. These specifications describe the documented interfaces; check the connectors and configuration on the individual terminal rather than assuming every unit is wired or equipped identically.
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Setup and operating states
The operator can inspect or select communication features in setup, including transmit and receive speed. The terminal also has setup, online, and local states. In local state, keyboard input goes to the monitor rather than the host, while received host data is stored until the terminal returns online. This separation of a host connection, serial settings, and local operation is central to understanding how the VT220 works. (VT220 Programmer Reference Manual)
How do you connect a VT220 to a modern computer?
A computer with a compatible RS-232 serial interface—or a USB-to-RS-232 adapter—may provide a way to connect a VT220 to a modern host. That is a practical inference from the terminal’s documented RS-232C host interface, not a guarantee that a particular adapter or cable will work.
- Identify the terminal’s actual host connection. Check the unit and its documentation to determine whether it has an RS-232C or 20 mA host interface. Do not select a cable based solely on the VT220 name.
- Verify the electrical interface and cable wiring. Confirm connector type, pinout, and cable wiring at both ends. A connector that physically fits does not by itself establish compatibility.
- Match the host’s serial settings. Use setup to inspect or select transmit and receive speed and the relevant character format, then configure the host accordingly. The manual documents asynchronous operation up to 19.2 kbit/s and 7-bit and 8-bit formats; the correct settings depend on the host and software.
- Test locally, then online. Local state directs keyboard input to the screen. Once the host connection and settings are ready, switch to online operation to send keystrokes to the host and display incoming data.
For archived manuals and other VT220 documentation, Bitsavers provides a documentation index. DEC VT220 Terminal Documentation Archive
What is the difference between VT220, VT100, and VT52 modes?
The VT220 supports four operating modes. The mode determines which control conventions the terminal uses, so choosing the right one depends on the host software.
| Mode | What it supports | When it matters |
|---|---|---|
| VT200, 7-bit controls | Full VT220 feature set in an 8-bit communications environment; this is the default mode. | Use it for software intended to use VT220 features. |
| VT200, 8-bit controls | VT200 operation using 8-bit controls. | Use it when the host software and communications setup expect 8-bit controls. |
| VT100 | Backward compatibility with VT100-family software; data is restricted to 7 bits. | Useful when older software expects VT100 behavior. |
| VT52 | DEC private functions rather than ANSI functions; intended for software written for the VT52. | Choose it for older software that specifically expects VT52 controls. |
These are compatibility choices, not different physical machines: the monitor and keyboard remain the VT220’s hardware while the selected mode changes how it communicates with software. (VT220 Programmer Reference Manual)
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is a VT220 emulator close enough to the real terminal?
An emulator can reproduce important parts of VT220 use, but it is not the same experience as operating the physical terminal. SecureCRT, for example, says it supports original VT220 control sequences and 80- or 132-column display, with versions for Windows, macOS, and Linux. That is a vendor’s description of one software option, not evidence that all emulators implement every VT220 behavior. SecureCRT VT220 Terminal Emulation Software
| Consideration | Physical VT220 | Emulator |
|---|---|---|
| Display and controls | Monochrome CRT monitor/system unit with a dedicated keyboard. | Software display and input on the computer running the emulator. |
| Connection | Requires a compatible serial host interface and correctly wired cable. | Uses the connection and session options provided by the emulator and host computer. |
| Display behavior | Hardware display with 80- or 132-column operation. | Some software options, including SecureCRT, state support for 80- or 132-column display. |
| Compatibility | Provides VT200, VT100, and VT52 modes. | Check the specific emulator for the control sequences and modes it supports. |
Choose the physical terminal when the CRT, dedicated keyboard, and original hardware interfaces are part of the goal. Choose an emulator when reproducing terminal behavior in software is sufficient and the specific software supports the required sequences and display modes.
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