DEC LK201

DEC LK201

Manufacturer	DEC
Layouts	105-key DEC "ANSI Layout" (aka. VMS Layout)
Interface	RS423, 4800 bps
Introduced	1982

The DEC LK201 keyboard was made by Digital Equipment Corporation (DEC) for the 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. Keycaps with cruciform pegs sit within a plastic assembly, and operate metal springs that press down on the membrane.<ref>Soretonaku Keyboard — 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 and caps lock keys are to the left of 'A'. The break and 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

Inverse-T layout introduced by the LK201

The LK201 is most famous for being the keyboard that popularised the inverse-T 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. "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 (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:

• Clones of the DEC LK201

Gallery

LK201

• 
  LK201 with special keycaps labelled for WPS/PLUS functions (WPS/PLUS was originally a stand-alone VAX/VMS product that was later incorporated into ALLIN1)
• 
  Top view
• 
  Bottom view
• 
  Removable feet
• 
  Product label

LK201AA

• 
  LK201 with standard keycaps
• 
  Top view
• 
  Bottom view
• 
  Side profile
• 
  Cursor key block
• 
  Function key label holder, not present on original LK201
• 
  Key mounts
• 
  Keycap stems, including extra spring for SHIFT
• 
  Leaf springs, left side view
• 
  Leaf springs, right side view
• 
  Without case
• 
  Reverse showing heat-staked mounts
• 
  Controller
• 
  Product label

References

<references />

External links

• LK201 on Wikipedia.
• ALLIN1 Information.
• More LK201 Pictures.