VT520

VT520
	CRT 80x24 or 132x24 characters
Input	Computer keyboard
Connectivity	RS-232
Predecessor	VT420

The VT520 is an ANSI standard computer terminal introduced by Digital Equipment Corporation (DEC) in 1993 and 1994.^[1] The VT520 is a multi-session monochrome text-only terminal with a built-in 14" monitor. The VT510 was a single-session version, while the VT525 added color support and used a separate external monitor.

The VT500s replaced all existing models of DEC's VT line, which at that time consisted of just the

IBM PC clones which could perform the same functions using a terminal emulator

while also running other software. DEC introduced the VT500s only a short time before selling off their entire terminal division in August 1995. This brought the VT series to a close, after a total of about six million terminals had been sold.

The VT520 was available from

Boundless Technologies

until the company went defunct in 2003.

Description

By the mid-1990s the price of low-end PCs was rapidly falling to under $1000. When equipped with a

PS/2 keyboard connector which made them easier to integrate into a mixed computing environment. They also had two DEC proprietary MMJ

serial connectors and a DEC proprietary keyboard port like their predecessors.

The VT510 was introduced in 1993 as an all-in-one unit with a built-in 14" display.

SVGA port for connection to an external user-supplied monitor.^[4]

Like all models of the VT series, the VT500's primary purpose is to act as an ANSI standard terminal. The VT510 supported only a single session, while the 520 and 525 supported up to four sessions, up from two in earlier VTs. The user can flip between the sessions using control sequences on the keyboard (typically F4), or display multiple sessions at the same time by splitting the screen horizontally or vertically. All models have multiple

sixels, and perform single-character swaps using the National Replacement Character Set

, swapping $ with £ for use with UK keyboards for instance.

The speed of the serial ports was increased to 115.2 kbps, up from 38.4 kbps on the VT300s. Any one of the serial ports could support two sessions using TD/SMP. Like earlier models of the VT line, the 500s could be put into modes emulating the

ADDS TeleVideo and other terminals. The 500s also directly supported ANSI commands for color, like the Wyse, in addition to the custom escape sequences

used for color support on previous VT models.

Another new feature was the inclusion of a set of

desk accessories

running on the terminal's CPU. These included a calculator, alarm clock, calendar, and a character set viewer.

Terminal emulator specifications may refer to VT500 instead of VT510, VT520 and VT525 in the statements about their compatibility.