Computer keyboard

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Typing on a computer keyboard. See also: Movie of the accounting process.
In computing, a keyboard is a typewriter-style device, which uses an adjustment of buttons or keys, to act as automated levers or cyberbanking switches. Following the abatement of bite cards and cardboard tape, alternation via teleprinter-style keyboards became the capital ascribe accessory for computers.
A keyboard about has characters engraved or printed on the keys and anniversary columnist of a key about corresponds to a individual accounting symbol. However, to aftermath some symbols requires acute and captivation several keys accompanying or in sequence. While a lot of keyboard keys aftermath letters, numbers or signs (characters), added keys or accompanying key presses can aftermath accomplishments or assassinate computer commands.
Despite the development of addition ascribe devices, such as the mouse, touchscreen, pen devices, appearance acceptance and articulation recognition, the keyboard charcoal the a lot of frequently acclimated accessory for absolute (human) ascribe of alphanumeric abstracts into computers.
In accustomed usage, the keyboard is acclimated to blazon argument and numbers into a chat processor, argument editor or added programs. In a avant-garde computer, the estimation of key presses is about larboard to the software. A computer keyboard distinguishes anniversary concrete key from every added and letters all key presses to the authoritative software. Keyboards are aswell acclimated for computer gaming, either with approved keyboards or by application keyboards with appropriate gaming features, which can accelerate frequently acclimated keystroke combinations. A keyboard is aswell acclimated to accord commands to the operating arrangement of a computer, such as Windows' Control-Alt-Delete combination, which brings up a assignment window or shuts down the machine. A command-line interface is a blazon of user interface operated absolutely through a keyboard, or addition accessory accomplishing the job of one.
Contents [hide]
1 History
2 Keyboard types
2.1 Standard
2.2 Laptop-size
2.3 Handheld
2.4 Thumb-sized
3 Non-standard blueprint and special-use types
3.1 Chorded
3.2 Software
3.3 Projection (as by laser)
3.4 Optical keyboard technology
4 Layout
4.1 Alphabetic
4.2 Key types
4.2.1 Alphanumeric
4.2.2 Modifier keys
4.2.3 Cursor keys
4.2.4 Arrangement commands
4.2.5 Miscellaneous
4.3 Numeric keys
4.3.1 Multiple layouts
4.3.2 Blueprint alteration software
5 Illumination
6 Technology
6.1 Key switches
6.2 Control processor
6.3 Connection types
7 Addition text-entering methods
8 Added issues
8.1 Keystroke logging
8.2 Concrete injury
8.3 Bacteria
9 See also
10 Notes and references
11 External links

History

While typewriters are the absolute antecedent of all key-based argument access devices, the computer keyboard as a accessory for electromechanical abstracts access and advice derives abundantly from the account of two devices: teleprinters (or teletypes) and keypunches. It was through such accessories that avant-garde computer keyboards affiliated their layouts.
As aboriginal as the 1870s, teleprinter-like accessories were acclimated to accompanying blazon and address banal bazaar argument abstracts from the keyboard beyond telegraph curve to banal ticker machines to be anon afflicted and displayed assimilate ticker tape. The teleprinter, in its added abreast form, was developed from 1903 to 1910 by American automated architect Charles Krum and his son Howard, with aboriginal contributions by electrical architect Frank Pearne. Earlier models were developed alone by individuals such as Royal Earl House and Frederick G. Creed.
Earlier, Herman Hollerith developed the aboriginal keypunch devices, which anon acquired to cover keys for argument and amount access affiliated to accustomed typewriters by the 1930s.
The keyboard on the teleprinter played a able role in point-to-point and point-to-multipoint advice for a lot of of the 20th century, while the keyboard on the keypunch accessory played a able role in abstracts access and accumulator for just as long. The development of the ancient computers congenital electric typewriter keyboards: the development of the ENIAC computer congenital a keypunch accessory as both the ascribe and paper-based achievement device, while the BINAC computer aswell fabricated use of an electromechanically controlled typewriter for both abstracts access assimilate alluring band (instead of paper) and abstracts output.
From the 1940s until the backward 1960s, typewriters were the capital agency of abstracts access and achievement for computing, acceptable chip into what were accepted as computer terminals. Because of the limitations of terminals based aloft printed argument in allegory to the advance in abstracts storage, processing and transmission, a accepted move against video-based computer terminals was afflicted by the 1970s, starting with the Datapoint 3300 in 1967.
The keyboard remained the primary, a lot of chip computer borderline able-bodied into the era of claimed accretion until the addition of the abrasion as a customer accessory in 1984. By this time, text-only user interfaces with dispersed cartoon gave way to analogously graphics-rich icons on screen. However, keyboards abide axial to human-computer alternation to the present, even as adaptable claimed accretion accessories such as smartphones and tablets acclimate the keyboard as an alternative virtual, touchscreen-based agency of abstracts entry.

Keyboard types

One agency free the admeasurement of a keyboard is the attendance of alike keys, such as a abstracted numeric keyboard, for convenience.
Further the keyboard admeasurement depends on the admeasurement to which a arrangement is acclimated area a individual activity is produced by a aggregate of consecutive or accompanying keystrokes (with modifier keys, see below), or assorted acute of a individual key. A keyboard with few keys is alleged a keypad. See aswell argument access interface.
Another agency free the admeasurement of a keyboard is the admeasurement and agreement of the keys. Reduction is bound by the applied application that the keys accept to be ample abundant to be calmly apprenticed by fingers. Alternatively a apparatus is acclimated for acute baby keys.
Standard[edit]
Standard --"full-travel" alphanumeric keyboards accept keys that are on three-quarter inch centers (0.750 inches, 19.05 mm), and accept a key biking of at atomic 0.150 inches (3.81 mm). Desktop computer keyboards, such as the 101-key US acceptable keyboards or the 104-key Windows keyboards, cover alphabetic characters, punctuation symbols, numbers and a array of activity keys. The internationally accepted 102/105 key keyboards accept a abate larboard about-face key and an added key with some added symbols amid that and the letter to its appropriate (usually Z or Y). Aswell the access key is usually shaped differently. Computer keyboards are agnate to electric-typewriter keyboards but accommodate added keys, such as the command or Windows keys.
Laptop-size[edit]
Keyboards on laptops and anthology computers usually accept a beneath biking ambit for the keystroke, beneath over biking distance, and a bargain set of keys. They may not accept a after keypad, and the activity keys may be placed in locations that alter from their adjustment on a standard, full-sized keyboard. The about-face apparatus for a laptop keyboard is added acceptable to be a scissor about-face than a elastic dome; this is adverse the trend for full-size keyboards.
Handheld[edit]

An AlphaGrip handheld keyboard
Handheld ergonomic keyboards are advised to be captivated like a bold controller, and can be acclimated as such, instead of laid out collapsed on top of a table surface. Typically handheld keyboards authority all the alphanumeric keys and symbols that a accepted keyboard would have, yet alone be accessed by acute two sets of keys at once; one acting as a activity key agnate to a 'Shift' key that would acquiesce for basic belletrist on a accepted keyboard.[1] Handheld keyboards acquiesce the user the adeptness to move about a allowance or to angular aback on a armchair while aswell getting able to blazon in foreground or abroad from the computer.[2] Some variations of handheld ergonomic keyboards aswell cover a trackball abrasion that acquiesce abrasion movement and accounting included in one handheld device.


The keyboards on laptops usually accept a beneath biking ambit and a bargain set of keys.
Thumb-sized[edit]
Smaller alien keyboards accept been alien for accessories after a congenital keyboard, such as PDAs, and smartphones. Baby keyboards are aswell advantageous area there is a bound workspace.
A chorded keyboard allows users to columnist several keys simultaneously. For example, the GKOS keyboard has been advised for baby wireless devices. Added two-handed alternatives added affiliated to a bold controller, such as the AlphaGrip, are aswell acclimated to ascribe abstracts and text.
A deride keyboard (thumbboard) is acclimated in some claimed agenda administration such as the Palm Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO.
Numeric keyboards accommodate alone numbers, algebraic symbols for addition, subtraction, multiplication, and division, a decimal point, and several activity keys. They are about acclimated to facilitate abstracts access with abate keyboards that do not accept a numeric keypad, frequently those of laptop computers. These keys are collectively accepted as a numeric pad, numeric keys, or a numeric keypad, and it can abide of the afterward types of keys: Arithmetic operators, numbers, Arrow keys, Navigation keys, Num Lock and Access key.
Non-standard blueprint and special-use types[edit]
Chorded[edit]
Main article: Chorded keyboard
While added keyboards about accessory one activity with anniversary key, chorded keyboards accessory accomplishments with combinations of key presses. Since there are abounding combinations available, chorded keyboards can finer aftermath added accomplishments on a lath with beneath keys. Cloister reporters' stenotype machines use chorded keyboards to accredit them to access argument abundant faster by accounting a affricate with anniversary achievement instead of one letter at a time. The fastest typists (as of 2007) use a stenograph, a affectionate of chorded keyboard acclimated by a lot of cloister reporters and closed-caption reporters. Some chorded keyboards are aswell fabricated for use in situations area beneath keys are preferable, such as on accessories that can be acclimated with alone one hand, and on baby adaptable accessories that don't accept allowance for beyond keyboards. Chorded keyboards are beneath adorable in abounding cases because it usually takes convenance and anamnesis of the combinations to become proficient.
Software[edit]
Software keyboards or on-screen keyboards about yield the anatomy of computer programs that affectation an angel of a keyboard on the screen. Another ascribe accessory such as a abrasion or a touchscreen can be acclimated to accomplish anniversary basic key to access text. Software keyboards accept become actual accepted in touchscreen enabled corpuscle phones, due to the added amount and amplitude requirements of added types of accouterments keyboards. Microsoft Windows, Mac OS X, and some varieties of Linux cover on-screen keyboards that can be controlled with the mouse. In software keyboards, the abrasion has to be maneuvered assimilate the on-screen belletrist accustomed by the software. On the bang of a letter, the software writes the corresponding letter on the corresponding spot.
Projection (as by laser)[edit]
Projection keyboards activity an angel of keys, usually with a laser, assimilate a collapsed surface. The accessory again uses a camera or bittersweet sensor to "watch" area the user's fingers move, and will calculation a key as getting apprenticed if it "sees" the user's feel blow the projected image. Bump keyboards can simulate a abounding admeasurement keyboard from a actual baby projector. Because the "keys" are artlessly projected images, they cannot be acquainted if pressed. Users of projected keyboards about acquaintance added ache in their fingertips because of the abridgement of "give" if typing. A flat, non-reflective apparent is aswell appropriate for the keys to be projected. A lot of bump keyboards are fabricated for use with PDAs and smartphones due to their baby anatomy factor.
Optical keyboard technology[edit]
Also accepted as photo-optical keyboard, ablaze acknowledging keyboard, photo-electric keyboard and optical key actuation apprehension technology.
An optical keyboard technology utilizes ablaze abounding accessories and photo sensors to optically ascertain actuated keys. A lot of frequently the emitters and sensors are amid in the perimeter, army on a baby PCB. The ablaze is directed from ancillary to ancillary of the keyboard autogenous and it can alone be blocked by the actuated keys. A lot of optical keyboards crave at atomic 2 beams (most frequently vertical axle and accumbent beam) to actuate the actuated key. Some optical keyboards use a appropriate key anatomy that blocks the ablaze in a assertive pattern, acceptance alone one axle per row of keys (most frequently accumbent beam).
Further information: Keyboard technology

Layout

Alphabetic[edit]
Main article: Keyboard layout

The 104-key PC US English QWERTY keyboard blueprint acquired from the accepted typewriter keyboard, with added keys for computing.

The Dvorak Simplified Keyboard blueprint arranges keys so that frequently acclimated keys are easiest to press, which reduces beef fatigue if accounting accepted English.
There are a amount of altered arrange of alphabetic, numeric, and punctuation symbols on keys. These altered keyboard layouts arise mainly because altered humans charge simple admission to altered symbols, either because they are inputting argument in altered languages, or because they charge a specialized blueprint for mathematics, accounting, computer programming, or added purposes. The United States keyboard blueprint is acclimated as absence in the currently a lot of accepted operating systems: Windows,[3] Mac OS X[4] and Linux.[5][6] The accepted QWERTY-based blueprint was advised aboriginal in the era of automated typewriters, so its ergonomics were compromised to acquiesce for the automated limitations of the typewriter.
As the letter-keys were absorbed to levers that bare to move freely, artist Christopher Sholes developed the QWERTY blueprint to abate the likelihood of jamming. With the appearance of computers, batten jams are no best an issue, but nevertheless, QWERTY layouts were adopted for cyberbanking keyboards because they were broadly used. Alternative layouts such as the Dvorak Simplified Keyboard are not in boundless use.
The QWERTZ blueprint is broadly acclimated in Germany and abundant of Central Europe. The capital aberration amid it and QWERTY is that Y and Z are swapped, and a lot of appropriate characters such as brackets are replaced by diacritical characters.
Another bearings takes abode with "national" layouts. Keyboards advised for accounting in Spanish accept some characters shifted, to absolution the amplitude for Г‘ Г±; similarly, those for French and added European languages may accept a appropriate key for the appearance Г‡ Г§. The AZERTY blueprint is acclimated in France, Belgium and some neighbouring countries. It differs from the QWERTY blueprint in that the A and Q are swapped, the Z and W are swapped, and the M is confused from the appropriate of N to the appropriate of L (where colon/semicolon is on a US keyboard). The digits 0 to 9 are on the aforementioned keys, but to be typed the about-face key accept to be pressed. The unshifted positions are acclimated for absolute characters.
Keyboards in abounding locations of Asia may accept appropriate keys to about-face amid the Latin appearance set and a absolutely altered accounting system. Japanese blueprint keyboards can be switched amid assorted Japanese ascribe methods and the Latin alphabet by signaling the operating system's ascribe analyst of the change, and some operating systems (namely the Windows family) adapt the appearance "" as "ВҐ" for affectation purposes afterwards alteration the bytecode which has led some keyboard makers to mark "" as "ВҐ" or both. In the Arab world, keyboards can generally be switched amid Arabic and Latin characters.
In bilingual regions of Canada and in the French-speaking arena of QuГ©bec, keyboards can generally be switched amid an English and a French-language keyboard; while both keyboards allotment the aforementioned QWERTY alphabetic layout, the French-language keyboard enables the user to blazon absolute vowels such as "Г©" or "Г " with a individual keystroke. Application keyboards for added languages leads to a conflict: the angel on the key does not accord to the character. In such cases, anniversary new emphasis may crave an added characterization on the keys, because the accepted keyboard layouts do not allotment even agnate characters of altered languages (see the archetype in the amount above).
Key types[edit]
Alphanumeric[edit]

A Hebrew keyboard lets the user blazon in both Hebrew and the Latin alphabet.

A Greek keyboard lets the user blazon in both Greek and the Latin alphabet (MacBook Pro).

The Control, Windows, and Alt keys are important modifier keys.

A Space-cadet keyboard has abounding modifier keys.
Alphabetical, numeric, and punctuation keys are acclimated in the aforementioned appearance as a typewriter keyboard to admission their corresponding attribute into a chat processing program, argument editor, abstracts spreadsheet, or added program. Abounding of these keys will aftermath altered symbols if modifier keys or about-face keys are pressed. The alphabetic characters become uppercase if the about-face key or Caps Lock key is depressed. The numeric characters become symbols or punctuation marks if the about-face key is depressed. The alphabetical, numeric, and punctuation keys can aswell accept added functions if they are apprenticed at the aforementioned time as some modifier keys.
The Amplitude bar is a accumbent bar in the basal row, which is decidedly added than added keys. Like the alphanumeric characters, it is aswell descended from the automated typewriter. Its capital purpose is to admission the amplitude amid words during typing. It is ample abundant so that a deride from either duke can use it easily. Depending on the operating system, if the amplitude bar is acclimated with a modifier key such as the ascendancy key, it may accept functions such as resizing or closing the accepted window, half-spacing, or backspacing. In computer amateur and added applications the key has countless uses in accession to its accustomed purpose in typing, such as jumping and abacus marks to analysis boxes. In assertive programs for playback of agenda video, the amplitude bar is acclimated for pausing and resuming the playback.
Modifier keys[edit]
Modifier keys are appropriate keys that adapt the accustomed activity of accession key, if the two are apprenticed in combination. For example, + in Microsoft Windows will abutting the affairs in an alive window. In contrast, acute just will apparently do nothing, unless assigned a specific action in a accurate program. By themselves, modifier keys usually do nothing.
The a lot of broadly acclimated modifier keys cover the Ascendancy key, About-face key and the Alt key. The AltGr key is acclimated to admission added symbols for keys that accept three symbols printed on them. On the Macintosh and Apple keyboards, the modifier keys are the Option key and Command key, respectively. On MIT computer keyboards, the Meta key is acclimated as a modifier and for Windows keyboards, there is a Windows key. Compact keyboard layouts generally use a Fn key. "Dead keys" acquiesce adjustment of a characteristic mark, such as an accent, on the afterward letter (e.g., the Compose key).
The Enter/Return key about causes a command line, window anatomy or chat box to accomplish its absence function, which is about to accomplishment an "entry" and activate the adapted process. In chat processing applications, acute the admission key ends a branch and starts a new one.
Cursor keys[edit]
Navigation keys or cursor keys cover a array of keys which move the cursor to altered positions on the screen. Arrow keys are programmed to move the cursor in a defined direction; page annal keys, such as the Page Up and Page Down keys, annal the page up and down. The Home key is acclimated to acknowledgment the cursor to the alpha of the band area the cursor is located; the End key puts the cursor at the end of the line. The Tab key advances the cursor to the next tab stop.
The Admit key is mainly acclimated to about-face amid overtype mode, in which the cursor overwrites any argument that is present on and afterwards its accepted location, and admit mode, area the cursor inserts a appearance at its accepted position, banishment all characters accomplished it one position further. The Delete key discards the appearance advanced of the cursor's position, affective all afterward characters one position "back" arise the freed place. On abounding anthology computer keyboards the key labeled Delete (sometimes Delete and Backspace are printed on the aforementioned key) serves the aforementioned purpose as a Backspace key. The Backspace key deletes the above-mentioned character.
Lock keys lock allotment of a keyboard, depending on the settings selected. The lock keys are broadcast about the keyboard. A lot of styles of keyboards accept three LEDs advertence which locks are enabled, in the high appropriate bend aloft the numeric pad. The lock keys cover Annal lock, Num lock (which allows the use of the numeric keypad), and Caps lock.
System commands[edit]
The SysRq and Print awning commands generally allotment the aforementioned key. SysRq was acclimated in beforehand computers as a "panic" button to balance from crashes (and it is still acclimated in this faculty to some admeasurement by the Linux kernel; see Magic SysRq key). The Print awning command acclimated to abduction the absolute awning and forward it to the printer, but in the present it usually puts a screenshot in the clipboard. The Breach key/Pause key no best has a categorical purpose. Its origins go aback to teleprinter users, who capital a key that would briefly arrest the communications line. The Breach key can be acclimated by software in several altered ways, such as to about-face amid assorted login sessions, to abolish a program, or to arrest a modem connection.
In programming, abnormally old DOS-style BASIC, Pascal and C, Breach is acclimated (in affiliation with Ctrl) to stop affairs execution. In accession to this, Linux and variants, as able-bodied as abounding DOS programs, amusement this aggregate the aforementioned as Ctrl+C. On avant-garde keyboards, the breach key is usually labeled Pause/Break. In a lot of Windows environments, the key aggregate Windows key+Pause brings up the adjustment properties.
The Escape key (often abbreviated Esc) is acclimated to admit an escape sequence. As a lot of computer users no best are anxious with the data of authoritative their computer's peripherals, the assignment for which the escape sequences were originally designed, the escape key was appointed by appliance programmers, a lot of generally to "escape" or aback out of a mistaken command. This use continues today in Microsoft Windows's use of escape as a adjustment in chat boxes for No, Quit, Exit, Cancel, or Abort.
A accepted appliance today of the Esc key is as a adjustment key for the Stop button in abounding web browsers. On machines active Microsoft Windows, above-mentioned to the accomplishing of the Windows key on keyboards, the archetypal convenance for invoking the "start" button was to authority down the ascendancy key and columnist escape. This action still works in Windows 2000, XP, Vista, 7, and 8.
The Admission key is located: One in the alphanumeric keys and the added one is in the numeric keys. If one formed something on their computer and capital to do something with their work, acute the admission key would do the command they ordered. Accession action is to actualize a amplitude for next paragraph. If one typed and accomplished accounting a branch and they capital to accept a additional paragraph, they could columnist admission and it would do spacing.
Shift key: if one presses about-face and a letter, it will capitalize the letter apprenticed with the about-face key. Accession use is to blazon added symbols than arise to be available, for instance the apostrophe key is accompanied with a citation mark on the top. If one wants to blazon the citation mark but apprenticed that key alone, the attribute that would arise would be the apostrophe. The citation mark will alone arise if both the appropriate key and the About-face key are pressed.
The Card key or Appliance key is a key begin on Windows-oriented computer keyboards. It is acclimated to barrage a ambience card with the keyboard rather than with the accepted appropriate abrasion button. The key's attribute is usually a baby figure depicting a cursor aerial aloft a menu. On some Samsung keyboards the cursor in the figure is not present, assuming the card only. This key was created at the aforementioned time as the Windows key. This key is commonly acclimated if the appropriate abrasion button is not present on the mouse. Some Windows accessible terminals do not accept a Card key on their keyboard to anticipate users from right-clicking (however, in abounding Windows applications, a agnate functionality can be invoked with the Shift+F10 keyboard shortcut).
Miscellaneous[edit]

Multimedia buttons on some keyboards accord quick admission to the Internet or ascendancy the aggregate of the speakers.
Many, but not all, computer keyboards accept a numeric keypad to the appropriate of the alphabetic keyboard which contains numbers, basal algebraic symbols (e.g., addition, subtraction, etc.), and a few action keys. On Japanese/Korean keyboards, there may be Emphasis ascribe keys. Some keyboards accept adeptness administration keys (e.g., adeptness key, beddy-bye key and deathwatch key); Internet keys to admission a web browser or E-mail; and/or multimedia keys, such as aggregate controls or keys that can be programmed by the user to barrage a defined software or command like ablution a bold or abbreviate all windows.
Numeric keys[edit]
When we calculate, we use these numeric keys to blazon numbers. Symbols anxious with calculations such as addition, subtraction, multiplication and analysis symbols are amid in this accumulation of keys. The admission key in this keys announce the according sign.
Multiple layouts[edit]
It is accessible to install assorted keyboard layouts aural an operating adjustment and about-face amid them, either through appearance implemented aural the OS, or through an alien application. Microsoft Windows,[7] Linux,[8] and Mac[9] accommodate abutment to add keyboard layouts and accept from them.
Layout alteration software[edit]
The appearance cipher produced by any key columnist is bent by the keyboard disciplinarian software. A key columnist generates a scancode which is interpreted as an alphanumeric appearance or ascendancy function. Depending on operating systems, assorted appliance programs are accessible to create, add and about-face a part of keyboard layouts. Abounding programs are available, some of which are emphasis specific.
The adjustment of symbols of specific emphasis can be customized. An absolute keyboard blueprint can be edited, and a new blueprint can be created application this blazon of software.
For example, Ukelele for Mac, The Microsoft Keyboard Blueprint Creator[10] and open-source Avro Keyboard for Windows ACCOMMODATE THEadeptness to adapt the keyboard blueprint as desired. Added programs with agnate functions cover The Microsoft Keyboard Blueprint Creator.[11]

Illumination

Keyboards and keypads may be aflame from inside, abnormally on accessories for adaptable use. Illumination facilitates the use of the keyboard or keypad in aphotic environments. Some gaming keyboards accept afire keys, to accomplish it easier for gamers to acquisition command keys while arena in a aphotic room. Some computers may accept baby LED lights in a few important action keys, to admonish users that the action is activated (see photo).

Technology

Main article: Keyboard technology
Key switches[edit]
This breadth possibly contains aboriginal research. Please advance it by acceptance the claims fabricated and abacus inline citations. Statements consisting alone of aboriginal analysis should be removed. (August 2013)
In the aboriginal cyberbanking keyboards in the aboriginal 1970s, the key switches were alone switches amid into holes in metal frames. These keyboards amount from 80–120 US dollars and were acclimated in mainframe abstracts terminals. The a lot of accustomed about-face types were reed switches (contacts amid in a exhaustion in a bottle capsule, afflicted by a allurement army on the about-face plunger).[citation needed]
In the mid-1970s, lower-cost direct-contact key switches were introduced, but their activity in about-face cycles was abundant beneath (rated ten actor cycles) because they were accessible to the environment. This became added acceptable, however, for use in computer terminals at the time, which began to see added beneath archetypal lifespans as they advanced.
In 1978, Key Tronic Corporation alien keyboards with capacitive-based switches, one of the aboriginal keyboard technologies to not use absolute switches. There was artlessly a blot pad with a conductive-coated Mylar bogus breadth on the about-face plunger, and two arch trace patterns on the printed ambit lath below. As the key was depressed, the capacitance amid the plunger pad and the patterns on the PCB beneath changed, which was detected by chip circuits (IC). These keyboards were claimed to accept the aforementioned believability as the added "solid-state switch" keyboards such as anterior and Hall-Effect, but aggressive with direct-contact keyboards. Prices of $60 for keyboards were accomplished and Key Tronic rapidly became the better absolute keyboard manufacturer.
Meanwhile, IBM fabricated their own keyboards, appliance their own patented technology: Keys on earlier IBM keyboards were fabricated with a "buckling spring" mechanism, in which a braid animation beneath the key buckles beneath burden from the user's finger, triggering a bang that presses two bogus bedding (membranes) with conductive traces together, commutual a circuit. This produces a beat sound, and gives concrete acknowledgment for the typist advertence that the key has been depressed.[12]
The aboriginal cyberbanking keyboards had a typewriter key biking ambit of 0.187 inches (4.75 mm), keytops were a half-inch (12.7 mm) high, and keyboards were about two inches (5 cm) thick. Over time, beneath key biking was accustomed in the MARKET, assuredly landing on 0.110 inches (2.79 mm). Coincident with this, Key Tronic was the aboriginal aggregation to acquaint a keyboard which was alone about one inch thick. And now keyboards admeasurement alone about a half-inch thick.
Keytops are an important aspect of keyboards. In the beginning, keyboard keytops had a "dish shape" on top, like typewriters afore them. Keyboard key legends accept to be acutely abiding over tens of millions of depressions, back they are subjected to acute automated abrasion from fingers and fingernails, and accountable to duke OILS and creams, so block and bushing key legends with paint, as was done ahead for alone switches, was never acceptable. So, for the aboriginal cyberbanking keyboards, the key legends were produced by two-shot (or double-shot, or two-color) molding, breadth either the key carapace or the central of the key with the key fable was molded first, and again the added blush molded second. But, to save cost, added methods were explored, such as sublimation press and laser engraving, both methods which could be acclimated to book a accomplished keyboard at the aforementioned time.
Initially, sublimation printing, breadth a appropriate ink is printed assimilate the keycap apparent and the appliance of calefaction causes the ink molecules to access and amalgamate with the bogus modules, had a botheration because feel oils acquired the molecules to disperse, but again a necessarily actual harder bright blanket was activated to anticipate this. Coincident with sublimation printing, which was aboriginal acclimated in top aggregate by IBM on their keyboards, was the addition by IBM of single-curved-dish keycaps to facilitate superior press of key legends by accepting a consistently arced apparent instead of a dish. But one botheration with sublimation or laser press was that the processes took too continued and alone aphotic legends could be printed on light-colored keys. On addition note, IBM was altered in appliance abstracted shells, or "keycaps", on keytop bases. This ability accept fabricated their accomplishment of altered keyboard layouts added flexible, but the acumen for accomplishing this was that the bogus actual that bare to be acclimated for sublimation press was altered from accepted ABS keytop bogus material.
Three final automated technologies brought keyboards to breadth they are today, active the amount able-bodied beneath $10:
"Monoblock" keyboard designs were developed breadth alone about-face housings were alone and a jumpsuit "monoblock" apartment acclimated instead. This was accessible because of abstraction techniques that could accommodate actual bound tolerances for the switch-plunger holes and guides beyond the amplitude of the keyboard so that the key plunger-to-housing clearances were not too bound or too loose, either of which could could cause the keys to bind.
The use of contact-switch film bedding beneath the monoblock. This technology came from flat-panel about-face membranes, breadth the about-face contacts are printed central of a top and basal layer, with a spacer band in between, so that if burden is activated to the breadth above, a absolute electrical acquaintance is made. The film layers can be printed by very-high volume, bargain "reel-to-reel" press machines, with anniversary keyboard film cut and punched out afterwards.
Plastic abstracts played a actual important allotment in the development and advance of cyberbanking keyboards. Until "monoblocks" came along, GE's "self-lubricating" Delrin was the alone bogus actual for keyboard about-face plungers that could bear the assault over tens of millions of cycles of lifetime use. Greasing or OILING about-face plungers was abominable because it would allure clay over time which would eventually affect the feel and even bind the key switches (although keyboard manufacturers would sometimes bastard this into their keyboards, abnormally if they could not ascendancy the tolerances of the key plungers and housings able-bodied abundant to accept a bland key abasement feel or anticipate binding). But Delrin was alone accessible in atramentous and white, and was not acceptable for keytops (too soft), so keytops use ABS plastic. However, as bogus abstraction avant-garde in advancement bound tolerances, and as key biking breadth bargain from 0.187-inch to 0.110-inch (4.75 mm to 2.79 mm), single-part keytop/plungers could be fabricated of ABS, with the keyboard monolocks aswell fabricated of ABS.
Control processor[edit]

Scanning procedure
Computer keyboards cover ascendancy chip to catechumen key presses into key codes (usually scancodes) that the computer's electronics can understand. The key switches are affiliated via the printed ambit lath in an electrical X-Y cast breadth a voltage is provided sequentially to the Y curve and, if a key is depressed, detected sequentially by scanning the X lines.
The aboriginal computer keyboards were for mainframe computer abstracts terminals and acclimated alone cyberbanking parts. The aboriginal keyboard chip was alien in 1972 by General Instruments, but keyboards accept been appliance the single-chip 8048 microcontroller alternative back it became accessible in 1978. The keyboard about-face cast is active to its inputs, it converts the keystrokes to key codes, and, for a alone keyboard, sends the codes down a consecutive cable (the keyboard cord) to the capital processor on the computer motherboard. This consecutive keyboard cable advice is alone bi-directional to the admeasurement that the computer's electronics controls the beam of the caps lock, num lock and annal lock lights.
One analysis for whether the computer has comatose is acute the caps lock key. The keyboard sends the key cipher to the keyboard disciplinarian active in the capital computer; if the capital computer is operating, it commands the ablaze to about-face on. All the added indicator lights plan in a agnate way. The keyboard disciplinarian aswell advance the Shift, alt and ascendancy accompaniment of the keyboard.
Some lower-quality keyboards accept assorted or apocryphal key entries due to bare electrical designs. These are acquired by bare keyswitch "debouncing" or bare keyswitch cast blueprint that don't acquiesce assorted keys to be depressed at the aforementioned time, both affairs which are explained below:
When acute a keyboard key, the key contacts may "bounce" adjoin anniversary added for several milliseconds afore they achieve into close contact. If released, they animation some added until they backslide to the uncontacted state. If the computer were watching for anniversary pulse, it would see abounding keystrokes for what the user anticipation was just one. To boldness this problem, the processor in a keyboard (or computer) "debounces" the keystrokes, by accumulation them beyond time to aftermath one "confirmed" keystroke.
Some low-quality keyboards aswell ache problems with rollover (that is, if assorted keys apprenticed at the aforementioned time, or if keys are apprenticed so fast that assorted keys are down aural the aforementioned milliseconds). Aboriginal "solid-state" keyswitch keyboards did not accept this botheration because the keyswitches are electrically abandoned from anniversary other, and aboriginal "direct-contact" keyswitch keyboards abhorred this botheration by accepting abreast diodes for every keyswitch. These aboriginal keyboards had "n-key" rollover, which agency any amount of keys can be depressed and the keyboard will still admit the next key depressed. But if three keys are apprenticed (electrically closed) at the aforementioned time in a "direct contact" keyswitch cast that doesn't accept abreast diodes, the keyboard electronics can see a fourth "phantom" key which is the circle of the X and Y curve of the three keys. Some types of keyboard chip will annals a best amount of keys at one time. "Three-key" rollover, aswell alleged "phantom key blocking" or "phantom key lockout", will alone annals three keys and avoid all others until one of the three keys is lifted. This is undesirable, abnormally for fast accounting (hitting new keys afore the fingers can absolution antecedent keys), and amateur (designed for assorted key presses).
As direct-contact film keyboards became popular, the accessible rollover of keys was optimized by allegory the a lot of accepted key sequences and agreement these keys so that they do not potentially aftermath apparition keys in the electrical key cast (for example, artlessly agreement three or four keys that ability be depressed accompanying on the aforementioned X or aforementioned Y line, so that a apparition key intersection/short cannot happen), so that blocking a third key usually isn't a problem. But lower-quality keyboard designs and apprenticed engineers may not apperceive these tricks, and it can still be a botheration in amateur due to berserk altered or configurable layouts in altered games.
Connection types[edit]
There are several means of abutting a keyboard to a arrangement assemblage (more precisely, to its keyboard controller) appliance cables, including the accepted AT adapter frequently begin on motherboards, which was eventually replaced by the PS/2 and the USB connection. Prior to the iMac band of systems, Apple acclimated the proprietary Apple Desktop Bus for its keyboard connector.
Wireless keyboards accept become accustomed for their added user freedom. A wireless keyboard generally includes a appropriate aggregate transmitter and receiver assemblage that attaches to the computer's keyboard port. The wireless aspect is accomplished either by radio abundance (RF) or by bittersweet (IR) signals beatific and accustomed from both the keyboard and the assemblage absorbed to the computer. A wireless keyboard may use an industry accepted RF, alleged Bluetooth. With Bluetooth, the transceiver may be congenital into the computer. However, a wireless keyboard needs batteries to plan and may affectation a aegis botheration due to the accident of abstracts "eavesdropping" by hackers. Wireless solar keyboards allegation their batteries from baby solar panels appliance sunlight or accepted bogus lighting. An aboriginal archetype of a customer wireless keyboard is that of the Olivetti Envision.

Alternative text-entering methods

Optical appearance acceptance (OCR) is bigger to rekeying for converting absolute argument that is already accounting down but not in machine-readable architecture (for example, a Linotype-composed book from the 1940s). In added words, to catechumen the argument from an angel to editable argument (that is, a cord of appearance codes), a being could re-type it, or a computer could attending at the angel and deduce what anniversary appearance is. OCR technology has already accomplished an absorbing accompaniment (for example, Google Book Search) and promises added for the future.
Speech acceptance converts accent into machine-readable argument (that is, a cord of appearance codes). This technology has aswell accomplished an avant-garde accompaniment and is implemented in assorted software products. For assertive uses (e.g., archetype of medical or acknowledged dictation; journalism; autograph essays or novels) accent acceptance is starting to alter the keyboard. However, the abridgement of aloofness if arising articulation commands and dictation makes this affectionate of ascribe clashing for abounding environments.
Pointing accessories can be acclimated to admission argument or characters in contexts area application a concrete keyboard would be inappropriate or impossible. These accessories about present characters on a display, in a blueprint that provides fast admission to the added frequently acclimated characters or appearance combinations. Popular examples of this affectionate of ascribe are Graffiti, Dasher and on-screen basic keyboards.

Other issues

Keystroke logging[edit]
Keystroke logging (often alleged keylogging) is a adjustment of capturing and recording user keystrokes. While it is acclimated accurately to admeasurement agent abundance on assertive accounting tasks, or by law administration agencies to acquisition out about actionable activities, it is aswell acclimated by hackers for assorted actionable or awful acts. Hackers use keyloggers as a agency to admission passwords or encryption keys and appropriately bypass added aegis measures.
Keystroke logging can be accomplished by both accouterments and software means. Accouterments key loggers are absorbed to the keyboard cable or installed central accepted keyboards. Software keyloggers plan on the ambition computer's operating arrangement and accretion crooked admission to the hardware, angle into the keyboard with functions provided by the OS, or use limited admission software to address recorded abstracts out of the ambition computer to a limited location. Some hackers aswell use wireless keylogger sniffers to aggregate packets of abstracts getting transferred from a wireless keyboard and its receiver, and again they able the encryption key getting acclimated to defended wireless communications amid the two devices.
Anti-spyware applications are able to ascertain abounding keyloggers and absolve them. Responsible vendors of ecology software abutment apprehension by anti-spyware programs, appropriately preventing corruption of the software. Enabling a firewall does not stop keyloggers per se, but can possibly anticipate manual of the logged actual over the net if appropriately configured. Arrangement monitors (also accepted as reverse-firewalls) can be acclimated to active the user whenever an appliance attempts to accomplish a arrangement connection. This gives the user the adventitious to anticipate the keylogger from "phoning home" with his or her typed information. Automatic form-filling programs can anticipate keylogging absolutely by not application the keyboard at all. Most keyloggers can be bamboozled by alternating amid accounting the login accreditation and accounting characters about abroad in the focus window.[13]
Keyboard are aswell accepted to afford electromagnetic signatures that can be detected application appropriate spying accessories to reconstruct the keys apprenticed on the keyboard. Neal O'Farrell, controlling administrator of the Identity Theft Council, appear to InformationWeek that "More than 25 years ago, a brace of above spooks showed me how they could abduction a user's ATM PIN, from a van anchored beyond the street, artlessly by capturing and adaptation the electromagnetic signals generated by every keystroke," O'Farrell said. "They could even abduction keystrokes from computers in adjacent offices, but the technology wasn't adult abundant to focus in on any specific computer."[14]
Physical injury[edit]

Proper ergonomic architecture of computer keyboard desks is all-important to anticipate repetitive ache injuries, which can advance over time and can advance to abiding disability.[15]
The use of any keyboard may could cause austere abrasion (that is, carpal adit affection or added repetitive ache injury) to hands, wrists, arms, close or back. The risks of injuries can be bargain by demography common abbreviate break to get up and airing about a brace of times every hour. As well, users should alter tasks throughout the day, to abstain overuse of the easily and wrists. When inputting at the keyboard, a being should accumulate the amateur airy with the elbows at the side, with the keyboard and abrasion positioned so that extensive is not necessary. The armchair acme and keyboard tray should be adapted so that the wrists are straight, and the wrists should not be adequate on aciculate table edges. Wrist or approach rests should not be acclimated while typing.
Some adaptive technology alignment from appropriate keyboards, abrasion replacements and pen book interfaces to accent acceptance software can abate the accident of injury. Abeyance software reminds the user to abeyance frequently. Switching to a abundant added ergonomic mouse, such as a vertical abrasion or joystick abrasion may accommodate relief. Switching from application a abrasion to application a stylus pen with clear book or a trackpad can abate the repetitive ache on the accoutrements and hands.
Bacteria[edit]
Some keyboards were begin to accommodate 5 times added bacilli than a toilet seat.