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 unt ...

of Maynard,

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

in 1982. It was first used by Digital's

VT220 The VT220 is a computer terminal introduced by Digital Equipment Corporation (DEC) in November 1983. The VT240 added monochrome ReGIS vector graphics support to the base model, while the VT241 did the same in color. The 200 series replaced the s ...

ANSI/ASCII terminal and was subsequently used by the

Rainbow-100 The Rainbow 100 is a microcomputer introduced by Digital Equipment Corporation (DEC) in 1982. This desktop unit had a monitor similar to the VT220 and a dual-CPU box with both Zilog Z80 and Intel 8088 CPUs. The Rainbow 100 was a triple-use m ...

, DECmate-II, and

Pro-350 The Professional 325 (PRO-325), Professional 350 (PRO-350), and Professional 380 (PRO-380) are PDP-11 compatible microcomputers introduced in 1982 by Digital Equipment Corporation (DEC) as high-end competitors to the IBM PC. History Like the c ...

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 either ...

and

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 (more widely known) two both released in 1989. These compri ...

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 palm-sized, usually-17-key section of a standard computer keyboard, usually on the far right. It provides calculator-style efficiency for entering numbers. The idea of a 10-key nu ...

. The

cursor keys Arrow keys or cursor movement keys are buttons on a computer keyboard that are either programmed or designated to move the cursor in a specified direction. The term "cursor movement key" is distinct from "arrow key" in that the former term may ...

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 A modular connector is a type of electrical connector for cords and cables of electronic devices and appliances, such as in computer networking, telecommunication equipment, and audio headsets. Modular connectors were originally developed fo ...

over which flowed power and

asynchronous serial Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal wit ...

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 machines. 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 f ...

layouts proved disruptive, but the LK201's key arrangement was emulated by the even more successful

Model M keyboard Model M designates a group of computer keyboards designed and manufactured by IBM starting in 1985, and later by Lexmark International, Maxi Switch, and Unicomp. The keyboard's many variations have their own distinct characteristics, with ...

and through it become 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 escape ...

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, multiuser 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, and ot ...

-oriented keyboard, the

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 DEC 3000 AXP workstations. The keyboard is optimized for use ...

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

. Many Unix users preferred a narrower,

ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...

-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