Editing DEC LK201

{{infobox dkeyboard
| image name   = LK201AA_top.jpg
| pn           = 
| branding     = 
| fcc          = 
| manufacturer = [[Digital Equipment Corporation|DEC]]
| switch       = 
| layouts      = 105-key DEC "ANSI Layout" (aka. VMS Layout)
| interface    = RS423, 4800 bps
| weight       =
| introduced   = 1982
| price        = 
}}

The '''DEC LK201''' keyboard was made by [[Digital Equipment Corporation]] (DEC) for the [http://terminals-wiki.org/wiki/index.php/DEC_VT220 DEC VT-220] terminal. Several succeeding terminals and workstations from DEC were compatible with this keyboard, and there were several compatible clones from other manufacturers.

==Construction==
The LK201 is a membrane keyboard. [[Keycap]]s with cruciform pegs sit within a plastic assembly, and operate metal springs that press down on the membrane.<ref>Soretonaku Keyboard — [http://park10.wakwak.com/~jpspace/key/kaitai_lk201.html 解体新書DEC LK201 Keyboard]</ref>

==Layout==
The layout of the LK201 has been very influential on subsequent systems. The main typing area has what later became the [[ISO]] layout, a QWERTY keyboard with a vertical Enter key, Tab to the left of 'Q' and a '<' key to the left of 'Z'. Like its predecessor, the keyboard for the VT102, both the [[control key|control]] and [[caps lock]] keys are to the left of 'A'. The break and [[delete key|delete]] keys were moved slightly to the right into a new group of keys, so that there was space to the right of the [[enter key]].

Function keys are on a top row, separated into several groups. There is also a [[numeric keypad]] on the right side with four additional function keys.

The LK201 was also (one of) the first keyboards to have a [[compose key]], which was situated to the left of the space bar.

===Inverse T===
[[File:Cursor keys--LK201.svg|right|thumb|Inverse-T layout introduced by the LK201]]

The LK201 is most famous for being the keyboard that popularised the inverse-T [[cursor keys|cursor key]] arrangement. While the LK201 was not the first keyboard to use this arrangement, it was chosen after serious studies into usability.<ref name="NerdCorner">Tim Burrows. [http://www.eldacur.com/~brons/NerdCorner/InverseT-History.html "Inverse-T History"], The Nerd Corner. Sep 21, 2009. (Acquired May 22, 2012)</ref> Whether the design was independently re-invented, or copied from an earlier keyboard, is not known.

===Followers===
DEC, being a major player in the computing industry in the early 1980s inspired many successors with its keyboard layouts.
The location of the cursor keys, the delete key and function keys were especially copied.

In 1983-1984 the IBM engineering task force developing the [[IBM Enhanced Keyboard|IBM Enhanced Keyboard (Model M)]] co-opted the layout of the LK201, including its signature inverted-T arrow cluster, but moved one row down.

Others layouts clearly influenced were [[Atari ST]] (1985), [[NEC PC-8801]] (from 1986) and [[Amiga]] (from 1987).
Apple copied IBM's layout with the [[Apple Extended Keyboard]] (1987).

==Variants==
There are many variants of the LK201 for localisation and other purposes. The keyboard code contains a two character suffix indicating the variant. For example, the LK201-AA is the USA/UK variant. There was a variant with APL keycaps, the LK201-EC.

==Copies==
Many keyboards copied the LK201 layout outright:

*[[:Category:Clones of the DEC LK201|Clones of the DEC LK201]]

==Gallery==
===LK201===
<gallery widths="250" heights="167">
File:LK201.jpg|LK201 with special keycaps labelled for [http://www.computinghistory.org.uk/det/15107/WPS-PLUS-for-VMS/ WPS/PLUS] functions (WPS/PLUS was originally a stand-alone VAX/VMS product that was later incorporated into [http://en.wikipedia.org/wiki/ALL-IN-1 ALLIN1])
File:LK201_top.jpg|Top view
File:LK201_bottom.jpg|Bottom view
File:LK201_feet.jpg|Removable feet
File:LK201_label.jpg|Product label
</gallery>
===LK201AA===
<gallery widths="250" heights="167">
File:LK201AA.jpg|LK201 with standard keycaps
File:LK201AA_top.jpg|Top view
File:LK201AA_bottom.jpg|Bottom view
File:LK201AA_profile.jpg|Side profile
File:LK201AA_cursor.jpg|Cursor key block
File:LK201AA_function_labels.jpg|Function key label holder, not present on original LK201
File:LK201AA_mounts.jpg|Key mounts
File:LK201AA_stems.jpg|Keycap stems, including extra spring for SHIFT
File:LK201AA_springs_left.jpg|Leaf springs, left side view
File:LK201AA_springs_right.jpg|Leaf springs, right side view
File:LK201AA_open.jpg|Without case
File:LK201AA_reverse.jpg|Reverse showing heat-staked mounts
File:LK201AA_controller.jpg|Controller
File:LK201AA_label.jpg|Product label
</gallery>

==References==
<references />

==External links==

*[https://en.wikipedia.org/wiki/LK201 LK201] on Wikipedia.
*[http://www.wickensonline.co.uk/retro/allin1.html ALLIN1] Information.
*[https://web.archive.org/web/20150510115857/http://www.wickensonline.co.uk/public-gallery/LK201/index.html More LK201 Pictures].

[[Category:Terminal keyboards]]
[[Category:DEC keyboards]]
[[Category:Vintage keyboards]]
[[Category:Keyboards with membrane switches]]
[[Category:List of all keyboards]]