View source for LK201

{{sources|date=September 2017}}
The '''LK201''' is a detachable computer keyboard introduced by [[Digital Equipment Corporation]] of [[Maynard, Massachusetts|Maynard]], [[Massachusetts]] in 1982. It was first used by Digital's [[VT220]] ANSI/ASCII terminal and was subsequently used by the [[Rainbow-100]], [[DECmate#DECmate II|DECmate-II]], and [[Pro-350]] microcomputers and many of Digital's computer workstations such as the [[VAXstation]] and [[DECstation]] families.

[[Image:Lk201.jpg|thumb|right]]

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 [[arrow keys|cursor keys]] were arranged in what has now become the standard "Inverted T" arrangement seen on essentially all contemporary full-sized computer keyboards.<ref>{{cite web | url=http://www.eldacur.com/~brons/NerdCorner/InverseT-History.html | title=Inverse-T History | author=Jim Burrows}}</ref><ref>{{cite conference | book-title=Proceedings of CHI '85 Human Factors in Computing Systems | author=Michael Good | pages=93–97 | url=http://michaelgood.info/publications/text-editing/the-use-of-logging-data-in-the-design-of-a-new-text-editor/ | title=The Use of Logging Data in the Design of a New Text Editor | publisher=[[Association for Computing Machinery]] | year=1985}}</ref> The keyboard also added a [[Compose key]] to allow typing of all of the characters in the terminal's [[Multinational Character Set|extended character set]] using two-stroke mnemonics, for instance {{keypress|Compose|u|"|chain=}} produced {{char|ü}}. An LED on the keyboard indicated an ongoing compose sequence.

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 {{nowrap|4 position}} [[modular connector]] over which flowed {{nowrap|12 [[volt]]}} power and {{nowrap|4800 bit/s}} [[Asynchronous serial communication|asynchronous serial]] data.

At the time of its introduction, the differences between the new layout and the traditional [[Teletype Model 33]] and [[VT100]] layouts proved disruptive, but the LK201's key arrangement was emulated by the even more successful [[Model M keyboard]] and through it became the de facto standard for all full-sized computer keyboards.  Today's standard layout differs primarily in the restoration of the [[Esc key|Escape Key]] found on the VT100 and that the [[numeric keypad]] has two double-height keys instead of one, decreasing the number pad keys from 18 to 17. The VT220 [[Compose key]] would survive in the European ISO standard but not in the U.S. ANSI standard.

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 [[Esc key|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.

== References ==
<references />

== External links ==
* [http://www.netbsd.org/docs/Hardware/Machines/DEC/lk201.html BSD documentation on LK201 keyboard]
* [https://web.archive.org/web/20070929174604/http://www.wickensonline.co.uk/public-gallery/LK201/index.html More pictures of the LK201 including internals]
* [http://www.netbsd.org/docs/Hardware/Machines/DEC/LK201_large_keycodes.jpg LK201 Keycode and Keyboard Division Chart (in color) (jpg 67k)] (The scancode of Right Shift is xab, not xae which is (Left) Shift only (see the next reference).
* [http://www.netbsd.org/docs/Hardware/Machines/DEC/lk201_keycodes.html LK201 Keycodes and Keyboard Divisions]

{{Digital Equipment Corporation}}

[[Category:Computer keyboard models]]
[[Category:DEC hardware]]