LK201
Encyclopedia
The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation
of Maynard
, Massachusetts
in 1982. It was first used by Digital's VT220
ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer workstations such as the VAXstation
and DECstation
families.
The keyboard layout was new at the time, adding a set of cursor and miscellaneous keys between the main keyboard and the numeric keypad. The cursor keys
were arranged in what has now become the standard "Inverted T" arrangement seen on essentially all contemporary full-sized computer keyboards. Ergonomic considerations caused the keyboard to be designed with a very low profile; it was very thin, especially when compared to the keyboard used on the VT100. The keyboard connected using a 4 position modular connector
over which flowed 12 volt
power and 4800 bit-per-second asynchronous serial data.
The keyboard also added a Compose key
. This allowed the typing of all of the characters in the terminal's extended character set using two-stroke mnemonics to represent the characters. An umlaut
, for example, ü could be typed by pressing the following sequence:
An LED on the keyboard indicated an on-going compose sequence.
At the time of its introduction, the differences between the new layout and the traditional ASR33
and VT100
layouts proved disruptive, but the LK201's key arrangement has become the defacto standard for all full-sized computer keyboards, differing primarily in the fact that the LK201's numeric keypad contained 18 keys and most subsequent layouts contain only 17 keys.
Follow-on keyboards from Digital refined the design introduced with the LK201. One notable departure from the basic LK201 design was a Unix
-oriented keyboard, the LK421
, that omitted the added middle group of cursor and miscellaneous function keys but included a dedicated Escape Key
. Many Unix users preferred a narrower, ASCII
-oriented keyboard rather than the rather-wide LK201 arrangement and the Escape Key was essential for several popular Unix editors.
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
of Maynard
Maynard, Massachusetts
Maynard is a town in Middlesex County, Massachusetts, United States. As of the 2010 census, the town population was 10,106.- History :Maynard, located on the Assabet River, was incorporated as an independent municipality in 1871. Prior to that it was known as 'Assabet Village' but was legally...
, Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
in 1982. It was first used by Digital's VT220
VT220
The VT220 was a terminal produced by Digital Equipment Corporation from 1983 to 1987.-Hardware:The VT220 improved on the earlier VT100 series of terminals with a redesigned keyboard, much smaller physical packaging, and a much faster microprocessor...
ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate-II, and Pro-350 microcomputers and many of Digital's computer workstations such as the VAXstation
VAXstation
The VAXstation was a family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture .- VAXstation I :...
and DECstation
DECstation
The DECstation was a brand of computers used by DEC, and refers to three distinct lines of computer systems—the first released in 1978 as a word processing system, and the latter two both released in 1989. These comprised a range of computer workstations based on the MIPS architecture and a...
families.
The keyboard layout was new at the time, adding a set of cursor and miscellaneous keys between the main keyboard and the numeric keypad. The cursor keys
Arrow keys
Cursor movement keys or arrow keys are buttons on a computer keyboard that are either programmed or designated to move the cursor in a specified direction....
were arranged in what has now become the standard "Inverted T" arrangement seen on essentially all contemporary full-sized computer keyboards. Ergonomic considerations caused the keyboard to be designed with a very low profile; it was very thin, especially when compared to the keyboard used on the VT100. The keyboard connected using a 4 position modular connector
Modular connector
Modular connector is the name given to a family of electrical connectors originally used in telephone wiring and now used for many other purposes. Many applications that originally used a bulkier, more expensive connector have now migrated to modular connectors...
over which flowed 12 volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
power and 4800 bit-per-second asynchronous serial data.
The keyboard also added a Compose key
Compose key
A compose key, available on some computer keyboards, is a special kind of modifier key designated to signal the software to interpret the following sequence of two keystrokes as a combination in order to produce a character not found directly on the keyboard...
. This allowed the typing of all of the characters in the terminal's extended character set using two-stroke mnemonics to represent the characters. An umlaut
Umlaut (diacritic)
The diaeresis and the umlaut are diacritics that consist of two dots placed over a letter, most commonly a vowel. When that letter is an i or a j, the diacritic replaces the tittle: ï....
, for example, ü could be typed by pressing the following sequence:
- Compose
- u
- " (double quote, mnemonically like the dots above the umlaut)
An LED on the keyboard indicated an on-going compose sequence.
At the time of its introduction, the differences between the new layout and the traditional ASR33
ASR33
The Teletype Model ASR-33 was a very popular model of teleprinter. Introduced about 1963 by Teletype Corporation and designed for light-duty office use, it was less rugged and less expensive than earlier Teletype machines or its heavy-duty cousin, the Model 35-ASR.The Model 33's printing mechanism...
and VT100
VT100
The VT100 is a video terminal that was made by Digital Equipment Corporation . Its detailed attributes became the de facto standard for terminal emulators.-History:...
layouts proved disruptive, but the LK201's key arrangement has become the defacto standard for all full-sized computer keyboards, differing primarily in the fact that the LK201's numeric keypad contained 18 keys and most subsequent layouts contain only 17 keys.
Follow-on keyboards from Digital refined the design introduced with the LK201. One notable departure from the basic LK201 design was a Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
-oriented keyboard, the LK421
LK421
The LK421 was a detachable computer keyboard manufactured by Digital Equipment Corporation of Maynard, Massachusetts and supplied as an option to the standard LK401 keyboard with their DECstation workstations...
, that omitted the added middle group of cursor and miscellaneous function keys but included a dedicated Escape Key
Esc key
On computer keyboards, the Esc key is a key labeled Esc or Escape that is used to generate the ASCII Escape character , the character code traditionally used to initiate an escape sequence...
. Many Unix users preferred a narrower, ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
-oriented keyboard rather than the rather-wide LK201 arrangement and the Escape Key was essential for several popular Unix editors.