A keyset or chorded keyboard (also called a chorded keyset, ''chord keyboard'' or ''chording keyboard'') is a
computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a "
chord" on a
piano
The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some early pianos used leather). It is played using a keyboa ...
. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device (such as a pocket-sized computer or a
bicycle handlebar
A bicycle handlebar is the steering control for bicycles. It is the equivalent of a tiller for vehicles and vessels, as it is most often directly mechanically linked to a pivoting front wheel via a stem which in turn attaches it to the fork. B ...
) that is too small to contain a normal-sized keyboard.
A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a
keyer
A keyer is a device for signaling by hand, by way of pressing one or more switches. Modern keyers typically have a large number of switches but not as many as a full-size keyboard; typically between four and fifty. A keyer differs from a keyboar ...
.
Douglas Engelbart
Douglas Carl Engelbart (January 30, 1925 – July 2, 2013) was an American engineer and inventor, and an early computer and Internet pioneer. He is best known for his work on founding the field of human–computer interaction, particularly ...
introduced the chorded keyset as a computer interface in 1968 at what is often called "
The Mother of All Demos
"The Mother of All Demos" is a name retroactively applied to a landmark computer demonstration, given at the Association for Computing Machinery / Institute of Electrical and Electronics Engineers (ACM/IEEE)—Computer Society's Fall Joint Compu ...
".
Principles of operation
Each key is mapped to a number and then can be mapped to a corresponding letter or command. By pressing two or more keys together the user can generate many combinations. In Engelbart's original mapping, he used five keys: 1, 2, 4, 8, 16. The keys were mapped as follows: a = 1, b = 2, c = 3, d = 4, and so on. If the user pressed keys 1 and 2 simultaneously, and then released the keys, 1 and 2 would be added to 3, and since C is the 3rd letter of the alphabet, and the letter "c" appeared. Unlike pressing a chord on a piano, the chord is recognized only after all the keys or mouse buttons are released. Since Engelbart introduced the keyset, several different designs have been developed based on similar concepts.
As a crude example, each finger might control one key which corresponds to one
bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...
in a
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
, so that using seven keys and seven fingers, one could enter any
character
Character or Characters may refer to:
Arts, entertainment, and media Literature
* ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk
* ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...
in the
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 ...
set—if the user could remember the binary codes. Due to the small number of keys required, chording is easily adapted from a desktop to mobile environment.
Practical devices generally use simpler chords for common characters (''e.g.,''
Baudot), or may have ways to make it easier to remember the chords (''e.g.,''
Microwriter
The Microwriter is a hand-held portable word-processor with a chording keyboard. First demonstrated in 1978, it was invented by UK-based, US-born film director Cy Endfield and his partner Chris Rainey and was marketed in the early 1980s by Microwr ...
), but the same principles apply. These portable devices first became popular with the
wearable computer
A wearable computer, also known as a body-borne computer, is a computing device worn on the body. The definition of 'wearable computer' may be narrow or broad, extending to smartphones or even ordinary wristwatches.
Wearables may be for general ...
movement in the 1980s.
Thad Starner from Georgia Institute of Technology and others published numerous studies showing that two-handed chorded text entry was faster and yielded fewer errors than on a
QWERTY
QWERTY () is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six Computer keyboard keys#Types, keys on the top left letter row of the keyboard ( ). The QWERTY design is based on a layout created f ...
keyboard. Currently
stenotype machine
A steno machine, stenotype machine, shorthand machine, stenograph or steno writer is a specialized chorded keyboard or typewriter used by stenographers for shorthand use. In order to pass the United States Registered Professional Reporter test, a ...
s hold the record for fastest word entry. Many stenotype users can reach 300 words per minute. However, stenographers typically train for three years before reaching professional levels of speed and accuracy.
History
The earliest known chord keyboard was part of the "five-needle"
telegraph
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas p ...
operator station, designed by
Wheatstone and
Cooke
Cooke is a surname derived from the occupation of cook. Notable people with the surname include:
* Alexander Cooke (died 1614), English actor
* Alfred Tyrone Cooke, of the Indo-Pakistani wars
* Alistair Cooke KBE (1908–2004), British-American j ...
in 1836, in which any two of the five needles could point left or right to indicate letters on a grid. It was designed to be used by untrained operators (who would determine which keys to press by looking at the grid), and was not used where trained telegraph operators were available.
The first widespread use of a chord keyboard was in the
stenotype machine used by court reporters, which was invented in 1868 and is still in use. The output of the stenotype was originally a phonetic code that had to be transcribed later (usually by the same operator who produced the original output), rather than arbitrary text—automatic conversion software is now commonplace.
In 1874, the five-bit
Baudot telegraph code and a matching 5-key chord keyboard was designed to be used with the operator forming the codes manually. The code is optimized for speed and low wear: chords were chosen so that the most common characters used the simplest chords. But telegraph operators were already using typewriters with QWERTY keyboards to "copy" received messages, and at the time it made more sense to build a typewriter that could generate the codes automatically, rather than making them learn to use a new input device.
![IBM 026 card code](https://upload.wikimedia.org/wikipedia/commons/8/8f/IBM_026_card_code.png)
Some early
keypunch
A keypunch is a device for precisely punching holes into stiff paper cards at specific locations as determined by keys struck by a human operator. Other devices included here for that same function include the gang punch, the pantograph punch, ...
machines used a keyboard with 12 labeled keys to punch the correct holes in paper cards. The numbers 0 through 9 were represented by one punch; 26 letters were represented by combinations of two punches, and symbols were represented by combinations of two or three punches.
Braille
Braille (Pronounced: ) is a tactile writing system used by people who are visually impaired, including people who are Blindness, blind, Deafblindness, deafblind or who have low vision. It can be read either on Paper embossing, embossed paper ...
(a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When
Louis Braille
Louis Braille (; ; 4 January 1809 – 6 January 1852) was a French educator and the inventor of a reading and writing system, named braille after him, intended for use by visually impaired people. His system is used worldwide and remains virtua ...
invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892,
Frank Haven Hall
Frank Haven Hall (February 9, 1841 – January 3, 1911) was an American inventor and essayist who is credited with inventing the Hall braille writer and the stereographer machine. He also invented the first successful mechanical point writer and ...
, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The
Perkins Brailler
The Perkins Brailler is a "braille typewriter" with a key corresponding to each of the six dots of the braille code, a space key, a backspace key, and a line space key. Like a manual typewriter, it has two side knobs to advance paper through t ...
, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been very successful as a mass market affordable product. Braille, like Baudot, uses a number symbol and a shift symbol, which may be repeated for shift lock, to fit numbers and upper case into the 63 codes that 6 bits offer.
After World War II, with the arrival of electronics for reading chords and looking in tables of "codes", the postal
sorting office
A sorting office or processing and distribution center (P&DC; name used by the United States Postal Service (USPS)) is any location where postal operators bring mail after collection for sorting into batches for delivery to the addressee, which ...
s started to research chordic solutions to be able to employ people other than trained and expensive typists. In 1954, an important concept was discovered: chordic production is easier to master when the production is done at the release of the keys instead of when they are pressed.
Researchers at
IBM investigated chord keyboards for both typewriters and computer data entry as early as 1959, with the idea that it might be faster than touch-typing if some chords were used to enter whole words or parts of words. A 1975 design by
IBM Fellow
An IBM Fellow is an appointed position at IBM made by IBM's CEO. Typically only four to nine (eleven in 2014) IBM Fellows are appointed each year, in May or June. Fellow is the highest honor a scientist, engineer, or programmer at IBM can achie ...
Nat Rochester had 14 keys that were dimpled on the edges as well as the top, so one finger could press two adjacent keys for additional combinations. Their results were inconclusive, but research continued until at least 1978.
Doug Engelbart
Douglas Carl Engelbart (January 30, 1925 – July 2, 2013) was an American engineer and inventor, and an early computer and Internet pioneer. He is best known for his work on founding the field of human–computer interaction, particularly ...
began experimenting with keysets to use with the mouse in the mid 1960s. In a famous 1968
demonstration, Engelbart introduced a computer human interface that included the
QWERTY
QWERTY () is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six Computer keyboard keys#Types, keys on the top left letter row of the keyboard ( ). The QWERTY design is based on a layout created f ...
keyboard, a three button
mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
, and a five key keyset. Engelbart used the keyset with his left hand and the mouse with his right to type text and enter commands. The mouse buttons marked selections and confirmed or aborted commands.
Users in Engelbart's Augmentation Research Center at
SRI
Shri (; , ) is a Sanskrit term denoting resplendence, wealth and prosperity, primarily used as an honorific.
The word is widely used in South and Southeast Asian languages such as Marathi, Malay (including Indonesian and Malaysian), Javanes ...
became proficient with the mouse and keyset. In the 1970s the funding Engelbart's group received from the
Advanced Research Projects Agency
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military.
Originally known as the Adv ...
(ARPA) was cut and many key members of Engelbart's team went to work for
Xerox PARC
PARC (Palo Alto Research Center; formerly Xerox PARC) is a research and development company in Palo Alto, California. Founded in 1969 by Jacob E. "Jack" Goldman, chief scientist of Xerox Corporation, the company was originally a division of Xero ...
where they continued to experiment with the mouse and keyset. Keychord sets were used at Xerox PARC in the early 1980s, along with mice,
GUI
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
s, on the Xerox Star and Alto workstations. A one button version of the mouse was incorporated into the
Apple Macintosh
The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software en ...
but
Steve Jobs
Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; a ...
decided against incorporating the chorded keyset.
![Xerox Alto keyset](https://upload.wikimedia.org/wikipedia/commons/6/67/Xerox_Alto_keyset.jpg)
In the early 1980s,
Philips
Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters i ...
Research labs at
Redhill, Surrey
Redhill () is a town in the borough of Reigate and Banstead within the county of Surrey, England. The town, which adjoins the town of Reigate to the west, is due south of Croydon in Greater London, and is part of the London commuter belt. The ...
did a brief study into small, cheap keyboards for entering text on a telephone. One solution used a grid of hexagonal keys with symbols inscribed into dimples in the keys that were either in the center of a key, across the boundary of two keys, or at the joining of three keys. Pressing down on one of the dimples would cause either one, two or three of the hexagonal buttons to be depressed at the same time, forming a chord that would be unique to that symbol. With this arrangement, a nine button keyboard with three rows of three hexagonal buttons could be fitted onto a telephone and could produce up to 33 different symbols. By choosing widely separated keys, one could employ one dimple as a 'shift' key to allow both letters and numbers to be produced. With eleven keys in a 3/4/4 arrangement, 43 symbols could be arranged allowing for lowercase text, numbers and a modest number of punctuation symbols to be represented along with a 'shift' function for accessing uppercase letters. While this had the advantage of being usable by untrained users via 'hunt and peck' typing and requiring one less key switch than a conventional 12 button keypad, it had the disadvantage that some symbols required three times as much force to depress them as others which made it hard to achieve any speed with the device. That solution is still alive and proposed by Fastap and Unitap among others, and a commercial phone has been produced and promoted in Canada during 2006.
Standards
Historically, the
baudot and
braille
Braille (Pronounced: ) is a tactile writing system used by people who are visually impaired, including people who are Blindness, blind, Deafblindness, deafblind or who have low vision. It can be read either on Paper embossing, embossed paper ...
keyboards were standardized to some extent, but they are unable to replicate the full character set of a modern keyboard. Braille comes closest, as it has been extended to eight bits.
The only proposed modern standard, GKOS (or
Global Keyboard Open Standard
Global means of or referring to a globe and may also refer to:
Entertainment
* Global (Paul van Dyk album), ''Global'' (Paul van Dyk album), 2003
* Global (Bunji Garlin album), ''Global'' (Bunji Garlin album), 2007
* Global (Humanoid album), ''Gl ...
) can support most characters and functions found on a computer keyboard but has had little commercial development. There is, however, a GKOS keyboard application available for iPhone since May 8, 2010, for Android since October 3, 2010 and for MeeGo Harmattan since October 27, 2011.
Stenography
Stenotype machines (sometimes used by Court Reporters) use a chording keyboard to represent sounds: on the standard keyboard, the 'U' represents the sound (and word) 'you', and the three-key trigraph 'K' 'A' 'T' represents the sound and word 'cat'. The stenotype keyboard is explicitly ordered 'K', on the left, is the starting sound. 'S' and 'T', which are common starting sounds and also common ending sounds, are available on both sides of the keyboard: 'TAT' is 3-key chord, using both T keys. .
Open-source designs
Four
open-source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...
keyer/keyset designs are available: The pickey, a
PS/2 device based on the
PIC microcontroller
PIC (usually pronounced as ''"pick"'') is a family of microcontrollers made by Microchip Technology, derived from the PIC1650"PICmicro Family Tree", PIC16F Seminar Presentation originally developed by General Instrument's Microelectronics ...
; the spiffchorder, a
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
device based on the
Atmel AVR
AVR is a family of microcontrollers developed since 1996 by Atmel, acquired by Microchip Technology in 2016. These are modified Harvard architecture 8-bit Reduced instruction set computer, RISC single-chip microcontrollers. AVR was one of the f ...
family of microcontrollers; the FeatherChorder, a BLE chorder based on the Adafruit Feather, an all-in-one board incorporating an
Arduino
Arduino () is an open-source hardware and software company, project, and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital devices. Its hardware products are licensed unde ...
-compatible microcontroller; and the GKOS keypad driver for
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
as well as the Gkos library for the Atmel/
Arduino
Arduino () is an open-source hardware and software company, project, and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital devices. Its hardware products are licensed unde ...
open-source board.
Plover is a free, open-source, cross-platform program intended to bring real-time stenographic technology not just to stenographers, but also to hobbyists using anything from professional
Stenotype machines to low-cost
NKRO
Key rollover is the ability of a computer keyboard to correctly handle several simultaneous keystrokes. A keyboard with ''n''-key rollover (NKRO) can correctly detect input from each key on the keyboard at the same time, regardless of how many oth ...
gaming keyboards. It is available for
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
,
Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
, and
macOS
macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
.
Joy2chord is a chorded keyboard driver for Linux. With a configuration file, any joystick or gamepad can be turned into a chorded keyboard. This design philosophy was decided on to lower the cost of building devices, and in turn lower the entry barrier to becoming familiar with chorded keyboards. Macro keys, and multiple modes are also easily implemented with a user space driver.
Commercial devices
One minimal chordic keyboard example is Edgar Matias' Half-Qwerty keyboard described in patent circa 1992 that produces the letters of the missing half when the user simultaneously presses the space bar along with the mirror key. INTERCHI '93 published a study by Matias, MacKenzie and Buxton showing that people who have already learned to touch-type can quickly recover 50 to 70% of their two-handed typing speed. The loss contributes to the speed discussion above. It is implemented on two popular mobile phones, each provided with software disambiguation, which allows users to avoid using the space-bar.
"Multiambic" keyers for use with wearable computers were invented in Canada in the 1970s. Multiambic keyers are similar to chording keyboards but without the board, in that the keys are grouped in a cluster for being handheld, rather than for sitting on a flat surface.
Chording keyboards are also used as portable but two handed input devices for the
visually impaired
Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment ...
(either combined with a
refreshable braille display
A refreshable braille display or braille terminal is an electro-mechanical device for displaying braille characters, usually by means of round-tipped pins raised through holes in a flat surface. Visually impaired computer users who cannot use a s ...
or vocal synthesis). Such keyboards use a minimum of seven keys, where each key corresponds to an individual
braille
Braille (Pronounced: ) is a tactile writing system used by people who are visually impaired, including people who are Blindness, blind, Deafblindness, deafblind or who have low vision. It can be read either on Paper embossing, embossed paper ...
point, except one key which is used as a spacebar. In some applications, the spacebar is used to produce additional chords which enable the user to issue editing commands, such as moving the
cursor
Cursor may refer to:
* Cursor (user interface), an indicator used to show the current position for user interaction on a computer monitor or other display device
* Cursor (databases), a control structure that enables traversal over the records in ...
, or deleting words. Note that the number of points used in braille computing is not 6, but 8, as this allows the user, among other things, to distinguish between small and capital letters, as well as identify the position of the cursor. As a result, most newer chorded keyboards for braille input include at least nine keys.
Touch screen chordic keyboards are available to
smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
users as an optional way of entering text. As the number of keys is low, the button areas can be made bigger and easier to hit on the small screen. The most common letters do not necessarily require chording as is the case with the GKOS keyboard optimised layouts (Android app) where the twelve most frequent characters only require single keys.
The company
CharaChorder
CharaChorder is an American privately held company that specializes in text input devices. Its major products include the CharaChorder One and the CharaChorder Lite, which are keyboards that allow for character and chorded entry.
History
The ...
commerially sells chorded entry devices. Their first commercially available device is the CharaChorder One, which features a split design with each having access to 9 switches that can be moved in five directions (up, down, left, right, and pressed) in contrast to typical keyboards. This device allows for both chorded entry as well as traditional character entry. The set of words that can be chorded can be dynamically changed by the user in real time, but by default includes the 300 most common words in the english language. This chorded entry feature allows for potentially extremely fast typing speeds, so much so the founder of the company has been banned from online typing competitions. Additionally, they create the Charachorder Lite with a more traditional keyboard design. The manufacturer claimed that users of the Charachorder One can reach speeds of 300 words per minute, while users of the Charachorder Lite can reach 250 words per minute.
Historical
The WriteHander, a 12-key chord keyboard from NewO Company, appeared in 1978 issues of ROM Magazine, an early microcomputer applications magazine.
Another early commercial model was the six-button
Microwriter
The Microwriter is a hand-held portable word-processor with a chording keyboard. First demonstrated in 1978, it was invented by UK-based, US-born film director Cy Endfield and his partner Chris Rainey and was marketed in the early 1980s by Microwr ...
, designed by
Cy Endfield
Cyril Raker Endfield (November 10, 1914 – April 16, 1995) was an American screenwriter, director, author, magician and inventor. Having been named as a Communist at a House Un-American Activities Committee hearing and subsequently blacklisted ...
and Chris Rainey, and first sold in 1980. Microwriting is the system of chord keying and is based on a set of mnemonics. It was designed only for right-handed use.
In 1982 the Octima 8 keys cord keyboard was presented by Ergoplic Kebords Ltd an Israeli Startup that was founded by Israeli researcher with intensive experience in Man Machine Interface design. The keyboard had 8 keys one for each finger and additional 3 keys that enabled the production of numbers, punctuations and control functions. The keyboard was fully compatible with the IBM PC & AT keyboards and had an Apple IIe version as well. Its key combinations were based on a mnemonic system that enabled fast and easy touch type learning. Within a few hours the user could achieve a typing speed similar to hand writing speed. The unique design also gave a relief from hand stress (Carpal Tunnel Syndrome) and allowed longer typing sessions than traditional keyboards. It was multi-lingual supporting English, German, French and Hebrew.
The
BAT
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...
is a 7-key hand-sized device from Infogrip, and has been sold since 1985. It provides one key for each finger and three for the thumb. It is proposed for the hand which does not hold the mouse, in an exact continuation of Engelbart's vision.
See also
*
BAT keyboard
*
FrogPad
FrogPad is a small chorded keyboard about the size of a numeric keypad that can be used with one hand. It was produced by Frogpad Inc.
The keyboard is optimized by character frequency. 85% of average keystrokes in English text can be typed with ...
*
Keyer
A keyer is a device for signaling by hand, by way of pressing one or more switches. Modern keyers typically have a large number of switches but not as many as a full-size keyboard; typically between four and fifty. A keyer differs from a keyboar ...
*
Microwriter
The Microwriter is a hand-held portable word-processor with a chording keyboard. First demonstrated in 1978, it was invented by UK-based, US-born film director Cy Endfield and his partner Chris Rainey and was marketed in the early 1980s by Microwr ...
*
Palantype
A speech-to-text reporter (STTR), also known as a captioner, is a person who listens to what is being said and inputs it, word for word (wikt:verbatim, verbatim), using an electronic shorthand keyboard, speech recognition software, or a CAT (Com ...
*
Stenotype
*
Velotype
Velotype is the trademark for a type of keyboard for typing text known as a syllabic chord keyboard, an invention of the Dutchmen Nico Berkelmans and Marius den Outer.
History
Marius den Outer invented the Tachotype in 1933. Herman Schweigma ...
syllable-chord keyboard
References
*Bardini, Thierry, ''Bootstrapping: Douglas Engelbart, Coevolution, and the Origins of Personal Computing'' (2000), Chapters 2 & 3, ,
*Engelbart and English, "A Research Center for Augmenting Human Intellect", ''AFIPS Conf. Proc.'', Vol 33, 1968 Fall Joint Computer Conference, p395-410
*Lockhead and Klemmer, ''An Evaluation of an 8-Key Word-Writing Typewriter'', IBM Research Report RC-180, IBM Research Center, Yorktown Heights, NY, Nov 1959.
*Rochester, Bequaert, and Sharp, "The Chord Keyboard", ''IEEE Computer'', December 1978, p57-63
*Seibel, "Data Entry Devices and Procedures", in ''Human Engineering Guide to Equipment Design'', Van Cott and Kinkade (Eds), 1963
{{Keyboard layouts
Computer keyboard types
Physical ergonomics