The LK201 is a detachable computer keyboard introduced by

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until ...

of Maynard,

Massachusetts Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...

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 The VAXstation is a discontinued family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture. VAXstation systems were typically shipped with eithe ...

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 A numeric keypad, number pad, numpad, or ten key, is the calculator-style group of ten numeric keys accompanied by other keys, usually on the far right side of computer keyboard. This grouping allows quick number entry with right hand, ...

. The cursor keys were arranged in what has now become the standard "Inverted T" arrangement seen on essentially all contemporary full-sized computer keyboards. The keyboard also added a

Compose key A compose key (sometimes called multi key) is a key on a computer keyboard that indicates that the following (usually 2 or more) keystrokes trigger the insertion of an alternate character, typically a precomposed character or a symbol. For insta ...

to allow typing of all of the characters in the terminal's extended character set using two-stroke mnemonics, for instance produced . 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 modular connector over which flowed power and asynchronous serial data. At the time of its introduction, the differences between the new layout and the traditional

Teletype Model 33 The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype models. The Teletype Corporation introduced the Model 33 as a commercial product in 1963, after ...

and

VT100 The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation (DEC). It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, and added a number of extended codes for special ...

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

Escape Key On computer keyboards, the Esc key (named ''Escape key'' in the international standard series ISO/IEC 9995) is a key used to generate the escape character (which can be represented as ASCII code 27 in decimal, Unicode U+001B, or ). The escap ...

found on the VT100 and that the

has two double-height keys instead of one, decreasing the number pad keys from 18 to 17. The VT220

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 Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

-oriented keyboard, the LK421, that omitted the added middle group of cursor and miscellaneous function keys but included a dedicated

. Many Unix users preferred a narrower,

ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

-oriented keyboard rather than the rather-wide LK201 arrangement and the Escape Key was essential for several popular Unix editors.

References

External links

BSD documentation on LK201 keyboard

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).

{{Digital Equipment Corporation Computer keyboard models DEC hardware