 Original DEC VT520, still in daily use in 2019 on an RS232 serialconsole crash cart in adata center. | |
| Manufacturer | DEC |
|---|---|
| Type | Computer terminal |
| Release date | September 1993 (1993-09) |
| Display | 14"CRT 80x24 or 132x24 characters |
| Input | Computer keyboard |
| Connectivity | RS-232 |
| Predecessor | VT420 |
TheVT520 is anANSI standardcomputer terminal introduced byDigital Equipment Corporation (DEC) in 1993 and 1994.[1] The VT520 is a multi-session monochrome text-only terminal with a built-in 14" monitor. TheVT510 was a single-session version, while theVT525 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 theVT420 text andVT340 graphics terminals. It was introduced in an era when the market was being flooded by low-costIBM PC clones which could perform the same functions using aterminal 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 fromBoundless Technologies until the company went defunct in 2003.
By the mid-1990s the price of low-end PCs was rapidly falling to under $1000. When equipped with aterminal emulator, these machines could perform all the functions of a DEC terminal, as well as running software locally. The terminal market began to crash, but remained important to DEC's coreminicomputer business. DEC responded by introducing the VT500 series as simplified and lower-cost options to the existingVT420 andVT340. The new 500s were text-only but they added anRS-232C serial port and aCentronics port as well as aPS/2 keyboard connector which made them easier to integrate into a mixed computing environment. They also had two DEC proprietaryMMJ serial connectors and a DEC proprietary keyboard port like their predecessors.
The VT510 was introduced in 1993 as an all-in-one unit with a built-in 14" display.[2] The VT520 was similar[3] but supported up to 4 sessions using a system known asTD/SMP.[a] The later VT525 color terminal dispensed with the integrated monitor as well, packaging the system into apizza box case with anSVGA port for connection to an external user-supplied monitor.[4]
Like all models of the VT series, the VT500's primary purpose is to act as an ANSI standard terminal. The VT510 supported only a single session, while the 520 and 525 supported up to four sessions, up from two in earlier VTs. The user can flip between the sessions using control sequences on the keyboard (typicallyF4), or display multiple sessions at the same time by splitting the screen horizontally or vertically. All models have multiplecharacter sets inROM, supporting DEC, international and PC characters. They can also replace any of these by downloading custom characters usingsixels, and perform single-character swaps using theNational Replacement Character Set, swapping$ 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 theVT100 andVT52, but added a wide variety of other emulations forWyse,ADDSTeleVideo and other terminals. The 500s also directly supported ANSI commands for color, like the Wyse, in addition to the customescape sequences used for color support on previous VT models.
Another new feature was the inclusion of a set ofdesk 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.
| Key people |
|  | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Instruction set architectures, processors |
| ||||||||
| Computer terminals | |||||||||
| Operating systems | |||||||||
| Programming languages | |||||||||
| Character sets |
| ||||||||
| Bus standards | |||||||||
| Otherhardware | |||||||||
| Related topics |
| ||||||||
