The 104-key PC US English QWERTY keyboard layout evolved from the standard typewriter keyboard with extra keys special to computing. The United States of America —commonly referred to as the English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States QWERTY (ˈkwɜː(rti is the most common modern-day Keyboard layout on English-language computer and Typewriter keyboards It takes its A typewriter is a mechanical or Electromechanical device with a set of "keys" that when pressed cause characters to be printed on a medium

The Dvorak Simplified Keyboard layout arranges keys so that frequently used keys are easiest to press. The Dvorak Simplified Keyboard (ˈdvɔræk or) is a Keyboard layout patented in 1936 by Dr Advocates of this keyboard layout claim that it reduces muscle fatigue when typing common English.

The standard Hebrew keyboard, shown here, lets the user type in both Hebrew and the Latin alphabet. A Hebrew keyboard ( Hebrew: מקלדת עברית mikledet ivrit) comes in two different Keyboard layouts Most Hebrew keyboards contain both Hebrew

The Microwriter MW4 (circa 1980), as used by Douglas Adams, features a chording keyboard

In computing, a keyboard is a peripheral partially modeled after the typewriter keyboard. The Microwriter is a hand-held portable word-processor with an innovative chording keyboard. Douglas Noël Adams (11 March 1952 &ndash 11 May 2001 was an English author comic Radio dramatist A keyset or chorded keyboard (also called a chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters Computing is usually defined like the activity of using and developing Computer technology Computer hardware and software. For an account of the words periphery and peripheral as they are used in biology sociology politics computer hardware and other fields see the A typewriter is a mechanical or Electromechanical device with a set of "keys" that when pressed cause characters to be printed on a medium

Physically, a keyboard is an arrangement of buttons, or keys. A push-button (often simply " button " or " pushbutton " is a simple Switch mechanism for controlling some aspect of a Machine A keyboard typically has characters engraved or printed on the keys; in most cases, each press of a key corresponds to a single written symbol. Engraving is the practice of incising a design onto a hard usually flat surface by cutting grooves into it Printing is a process for reproducing text and image typically with ink on Paper using a printing press The musical instrument is spelled Cymbal. A symbol is something --- such as an object, Picture, written word a sound a piece However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself. See input method editor.

A majority of all keyboard keys produce letters, numbers or signs (characters) that are appropriate for the operator's language. A letter is an element in an Alphabetic system of writing such as the Greek alphabet and its descendants A number is an Abstract object, tokens of which are Symbols used in Counting and measuring. A sign is an entity which signifies another entity A natural sign is an entity which bears a causal relation to the signified entity as thunder is a sign of storm For other uses see Character. In Computer and machine-based Telecommunications terminology a character is a unit of A language is a dynamic set of visual auditory or tactile Symbols of Communication and the elements used to manipulate them Other keys can produce actions when pressed, and other actions are available by the simultaneous pressing of more than one action key.

Designs

Keyboard layouts (QWERTY, Dvorak, et al)

Main article: Keyboard layout

There exists a large number of different arrangements of symbols on keys. QWERTY keyboardjpg|thumb|right|300px|QWERTY keyboard on a Laptop of 2007]]A keyboard layout is any specific mechanical, visual, or functional These different keyboard layouts arise mainly because different people need easy access to different symbols; typically, this is because they are writing in different languages, but specialized keyboard layouts for mathematics, accounting, and computer programming also exist. QWERTY keyboardjpg|thumb|right|300px|QWERTY keyboard on a Laptop of 2007]]A keyboard layout is any specific mechanical, visual, or functional

Most of the more common keyboard layouts (QWERTY-based and similar) were designed in the era of the mechanical typewriters, so their ergonomics had to be slightly compromised in order to tackle some of the technical limitations of the typewriters. QWERTY (ˈkwɜː(rti is the most common modern-day Keyboard layout on English-language computer and Typewriter keyboards It takes its The letters were attached to levers that needed to move freely; because jamming would result if commonly used letters were placed too close to one another, Christopher Sholes invented the QWERTY layout. Christopher Latham Sholes ( February 14, 1819 - February 17, 1890) was an American Inventor who invented the first However, with the advent of modern electronics, this is no longer an issue. QWERTY layouts and their brethren had been a de facto standard for decades prior to the introduction of the very first computer keyboard, and were primarily adopted for electronic keyboards for this reason. Alternative layouts do exist, the best known of which is Dvorak; however, these are not in widespread use. The Dvorak Simplified Keyboard (ˈdvɔræk or) is a Keyboard layout patented in 1936 by Dr

The number of keys on a keyboard varies from the standard of 101 keys introduced in the late 1980s to the 104-key Windows keyboards and all the way up to 130 keys or more, with many of the additional keys being symbol-less programmable keys that can simulate multiple functions such as starting a web browser or e-mail client. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. A web browser is a software application which enables a user to display and interact with text images videos music games and other information typically located on a An e-mail client, aka Mail User Agent (MUA aka e-mail reader is a frontend Computer program used to manage E-mail. There also were "Internet keyboards," sold in the late 1990s, that replaced the function keys with pre-programmed internet shortcuts. Pressing the shortcut keys would launch a browser to go to that website. A keyboard shortcut (or accelerator key, shortcut key, hot key, key binding, keybinding, key combo, etc

Connection types

There are several different ways of connecting a keyboard which have evolved over the years. These include the standard AT (DIN-5) connector commonly found on pre-80486 motherboards, which was eventually replaced by the PS/2 and USB connection. A DIN connector is a connector that was originally standardized by the Deutsches Institut für Normung (DIN the German national standards organization The PS/2 connector is used for connecting some keyboards and mice to a PC compatible computer system Prior to the iMac line of systems, Apple Computer used ADB, a proprietary system, for its keyboard connector. Apple Inc, ( formerly Apple Computer Inc, is an American Multinational corporation with a focus on designing and manufacturing Consumer electronics Apple Desktop Bus (or ADB) is an obsolete bit-serial Computer bus connecting low-speed devices to computers

Wireless types

Wireless keyboards have become popular for their increased user freedom. Wireless communication is the transfer of information over a distance without the use of electrical conductors or " Wires quot However, a wireless keyboard needs batteries to work and may pose a security problem due to the risk of eavesdropping. Eavesdropping is the act of surreptitiously listening to a private conversation ^[1]

A wireless keyboard often includes a required combination transmitter and receiver unit that attaches to the computer's keyboard port (see Connection types above). The wireless aspect is achieved either by radio frequency (RF) or by infrared (IR) signals sent and received from both the keyboard and the unit attached to the computer. Radio frequency ( RF) is a Frequency or rate of Oscillation within the range of about 3 Hz to 300 GHz Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of A wireless keyboard may use an industry standard RF, called Bluetooth. Bluetooth is a wireless protocol utilizing short-range communications technology facilitating data transmission over short distances from fixed and/or mobile devices creating wireless With Bluetooth, the transceiver may be built into the computer.

Buckling spring vs. dome switch

Keys on older IBM keyboards were made with a "buckling spring" mechanism, in which a coil spring under the key buckles under pressure from the user's finger, pressing a rubber dome, whose inside is coated with conductive graphite, which connects two leads below, completing a circuit. There are many types of keyboard, usually differentiated by the Switch technology employed in their operation This produces a clicking sound, and a "positive" feel of feedback, so that the typist knows when the key is fully pressed. Keys on most modern keyboards are made with a so-called "dome switch" mechanism, without the buckling spring. There are many types of keyboard, usually differentiated by the Switch technology employed in their operation In Computing, a keyboard is an Input device partially modelled after the typewriter keyboard which uses an arrangement of buttons or keys Many typists prefer the buckling spring board, which is still manufactured. ^[2][3]

Alternatives to the "regular" keyboard

Most keyboards are rigid, but this foldable keyboard demonstrates one of many variations from the usual.

A multimedia keyboard like this one offers special keys for accessing music, web, and other oft-used programs.

Specialty keyboards

A specialty keyboard is a standard keyboard with software keyboard shortcuts marked on color-coded keys. They help users to learn and use the keyboard shortcuts for particular software applications. A keyboard shortcut (or accelerator key, shortcut key, hot key, key binding, keybinding, key combo, etc It is very popular with videographers who have to spend hours editing their raw video. Videography refers to the process of capturing moving Images on Electronic media (e The keyboard helps to increase the speed of their work. It is also starting to catch on in other applications, such as graphic designers using Photoshop keyboards, audio editors using audio editing keyboards, etc. A graphic designer (also known as a graphic artist and communication designer) is a professional within the Graphic design and Graphic arts industry A digital audio editor is a computer application for Audio editing, i There is no reason why other applications such as word processing and email programs cannot take advantage of specialty keyboards' shortcut keycaps. Word processing is the creation of documents using a Word processor. Electronic mail, often abbreviated to e-mail, email, or originally eMail, is a Store-and-forward method of writing sending receiving

Smaller keyboards

A standard keyboard is physically quite large, as each key must remain large enough to be easily pressed by fingers. Other types of keyboards have been proposed for small portable equipment where a standard keyboard is too large. One way to reduce the size of the keyboard is to reduce the number of keys and use chording keyer, i. A keyset or chorded keyboard (also called a chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters A keyer is a device for signaling by hand by way of pressing one or more switches e. pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. A keyset or chorded keyboard (also called a chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters Other two-handed alternatives more akin to a game controller, such as the AlphaGrip, are also used as a way to input data and text. A game controller is an Input device used to control a Video game. The AlphaGrip is a hand-held Computer keyboard and game controller that is being marketed as an alternative to the traditional design

Another way to reduce the size of a keyboard is to use smaller buttons and pack them closer together. Such keyboards, often called a "thumbboard" (thumbing) are used in some personal digital assistants such as the Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO. A thumb keyboard, or a thumbboard is a type of keyboard commonly found on PDAs Mobile phones and PDA phones which has a familiar layout to an The BlackBerry is a Wireless Handheld device introduced in 1999 as a two-way pager In Personal computers Ultra-Mobile PC (often abbreviated UMPC) is a small Form factor (a standard size and shape for Tablet PCs and subnotebook/ OQO is a US computer hardware company the manufacturer of Subnotebook, handheld computers named the OQO model 02 and OQO model e2

Keyboards with extra keys

Multimedia keyboards

Multimedia keyboards offer special keys for accessing music, web, and other oft-used programs. They also usually have other convenient controls, such as a mute button, volume buttons or knob, and standby (sleep) button. The MUTE Network (or MUTE-net) is a Peer-to-peer and Friend-to-friend File sharing network developed with anonymity in mind KNOB is a commercial Radio station in Healdsburg California, broadcasting to the Santa Rosa California area on 96

Gaming keyboards

Some gaming keyboards offer extra function keys which can be programmed with keystroke macros. A personal computer Game (also known as a computer game or simply PC game) is a Video game played on a Personal computer, rather For example, ctrl+shift+y could be a keystroke that is frequently used in a certain computer game. But it is a physically awkward (or, at least, annoying) combination for the hands to reach for repeatedly. It may be very useful to assign that keystroke combination to one function key. Some keyboards (Such as the Logitech G11 or G15) have a keypad full of "G keys" to the left of the QWERTY keyboard for this purpose. The Logitech G11 is a keyboard produced by Logitech designed specifically for gamers The Logitech G15 is a keyboard produced by Logitech designed specifically for gamers The keystroke macros can be reprogrammed at will.

The development of these keyboards was spurred by gaming, but the concept can also be very convenient in non-gaming applications, such as office work. Any keystroke combination that is awkward or annoying but frequently needed can be replaced with a "G key". The meaning of the "G key" press can automatically change depending on which application has focus, thus extending the number of macros available given a certain limited number of G keys. In Computing, the focus indicates the component of the Graphical user interface which is currently selected to receive input

Virtual keyboards

A relatively new type of keyboard, the I-Tech Virtual Laser Keyboard, works by projecting an image of a full-size keyboard onto a surface. A projection keyboard is a Virtual keyboard that can be projected and touched on any surface Sensors in the projection unit identify which key is being "pressed" and relay the signals to a computer or personal digital assistant. A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument

Keyboard layout alternatives to QWERTY

As explained above, the QWERTY layout was a legacy from mechanical typewriters. In contrast, some keyboard layouts are specifically designed for speed. The most common is the Dvorak layout; more recently, hobbyists have designed other layouts in an attempt to improve on Dvorak and to be easier to learn for existing QWERTY users^[4]. The Dvorak Simplified Keyboard (ˈdvɔræk or) is a Keyboard layout patented in 1936 by Dr The fastest keyboard so far is the stenotype — some people who use a stenotype type faster than 300 words per minute. A stenotype or shorthand machine is a specialized Chorded keyboard or Typewriter used by Stenographers for Shorthand use Words per minute, commonly abbreviated wpm, is a measure of input or output speed

Input by alternate text input devices

It is possible to limit or eliminate the use of computer keyboards with the introduction of alternative methods not based in keystrokes, such as optical character recognition (OCR), speech recognition and pointing-device text input.

OCR

Optical character recognition (OCR) is preferable to rekeying for converting existing text that is already written down but not in machine-readable format (for example, a Linotype-composed book from the 1940s). Optical character recognition, usually abbreviated to OCR, is the Mechanical or electronic translation of Images of handwritten typewritten The Linotype machine (pronounced "Line-O-Type") is a "line casting" machine used in Printing. In other words, to convert the text from an image to editable text (that is, a string of character codes), a person could re-type it, or a computer could look at the image and deduce what each character is. For other uses see Character. In Computer and machine-based Telecommunications terminology a character is a unit of OCR technology has already reached an impressive state (for example, Google Book Search) and promises more for the future. Google Book Search is a tool from Google that searches the full text of books that Google scans OCRs, and stores in its digital database

Speech recognition

Speech recognition converts speech into machine-readable text (that is, a string of character codes). Speech recognition (also known as automatic speech recognition or computer speech recognition) converts spoken words to machine-readable input (for example to keypresses The technology has already reached an impressive state and is already implemented in various software products. Modern Speech recognition software enables a single Computer user to speak text and/or commands to the computer largely but not entirely bypassing the use For certain uses (e. g. , transcription of medical or legal dictation; journalism; writing essays or novels) it is starting to replace the keyboard; however, it does not threaten to replace keyboards entirely anytime soon. It can, however, interpret commands (for example, "close window" or "undo that") in addition to text. Therefore, it has theoretical potential to replace keyboards entirely (whereas OCR replaces them only for a certain kind of task).

Pointing-device text input

There is a class of hardware or software accessories enabling users to enter text efficiently using a pointing device, in contexts where using a physical keyboard would be inappropriate or impossible. A pointing device is an Input interface (specifically a Human interface device) that allows a user to input spatial (ie continuous and multi-dimensional data These accessories typically present characters on a display, in a layout that provides fast access to the more frequently used characters or character combinations. Popular examples of this kind of input are Graffiti, Dasher and on-screen virtual keyboards. Graffiti is the Handwriting recognition software used in PDAs based on the Palm OS. Dasher is a Computer accessibility tool which enables users to write without using a keyboard, by entering text on a screen using a Pointing device A virtual keyboard is a software and/or hardware component that allows a user to enter characters

FITALY (http://www.FITALY.com) is a stylus/one-finger keyboard that can yield 50+ WPM. The key is to stare at the keyboard, not the screen (as in traditional touch typing). No memorization of layout is required. It is engineered for rapid text input (e. g. , some 85% of English words are visible at the center of the keyboard). It is available for many mobile and laptop devices.

Standards

In principle, computer keyboard designs are governed by the ISO/IEC 9995 international standard. ISO/IEC 9995 (less formally "ISO 9995" is an ISO standard defining layouts of computer keyboards

Historical

While the IBM PC keyboard was hardly the first electronic keyboard, it does merit particular mention, if only for its ubiquity. The IBM PC keyboard and its derivative Computer keyboards are standardized The original IBM PC/XT had 83 keys; the AT keyboard had 84 (adding a SysRq key and separating keys into sections, also changing the communication protocol). Next came the "Enhanced" 101 keys (which duplicated the cursor movement keys from the numeric pad, added the function key row along the top and increased their number from 10 to 12, made other minor changes, and included an often-maligned control-key/caps-lock placement swap). The above-mentioned 104 keys were obtained by adding three "windows" keys. The internationally common 102/105 key keyboards have a smaller 'left shift' key and an additional key with some more symbols between that and the letter to its right (usually Z or Y). ^[5]

Usage

An on-screen keyboard controlled with the mouse can be used by users with limited mobility.

In normal usage, the keyboard is used to type text into a word processor, text editor, or any other textbox. A text editor is a type of program used for editing plain Text files Text editors are often provided with Operating systems or software development

In a modern computer the interpretation of keypresses is generally left to the software. A modern keyboard distinguishes each physical key from every other and report all keypresses to the controlling software. This flexibility is not often taken advantage of and it usually does not matter, for example, whether the left or right shift key is held down in conjunction with another character, even though they are coded as completely separate keys.

Keystroke

Laptop keyboards such as on this Sony VAIO have a shorter travel distance for the keystroke and usually have a reduced set of keys to make the keyboard (and laptop) more convenient to carry. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with VAIO, originally an Acronym for Video Audio Integrated Operation, but since 2008 amended to Visual Audio Intelligence Organizer to celebrate the

The term keystroke refers to the simple act of pressing a button on a keyboard that is connected to some form of digital computer. A computer is a Machine that manipulates data according to a list of instructions. The term is also frequently used to mean a keystroke combination (several keys pressed at once, for example, ctrl+shift+spacebar) used as a keyboard shortcut (also known as a shortcut key or other names). A keyboard shortcut (or accelerator key, shortcut key, hot key, key binding, keybinding, key combo, etc

Nefarious programs may log keystrokes and thereby capture such sensitive information as operating system passwords and credit card numbers. Keystroke logging (often called keylogging) is a method of capturing and recording user keystrokes

Commands

A keyboard is also used to type commands in a computer. One famous example on the PC is the Control-Alt-Delete combination. Control-Alt-Delete (often abbreviated to Ctrl-Alt-Del, also known as the "three-finger salute" is a computer keyboard command on PC compatible systems On most versions of Microsoft Windows, this command brings up a window (such as the Task Manager on Windows NT based versions of Windows) which allows users to manage currently-running processes, shut down the machine, and other functions. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. A task manager is a program used to provide information about the processes and programs running on a Computer, as well as the general status of the computer Windows NT is a family of Operating systems produced by Microsoft, the first version of which was released in July 1993 Under Linux, MS-DOS and some older versions of Windows, the command performs either a "cold" or "warm" reboot. Linux (commonly pronounced ˈlɪnəks MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. ReBoot is a Canadian CGI - animated action-adventure Television series that originally aired from 1994 to 2001

Games

A keyboard is one of the primary methods of control in computer games. A personal computer Game (also known as a computer game or simply PC game) is a Video game played on a Personal computer, rather For instance, the arrow keys or a group of letters resembling the pattern of the arrow keys, like WASD, can be used for movement of a game character. Cursor movement keys or arrow keys are buttons on a Computer keyboard that are either programmed or designated to move the cursor in a specified direction In many games, keys can be configured to the user's preferences. Alphabet keys are also sometimes used to perform actions starting with that letter. (e. g. pressing j to jump, r to reload or c to crouch). As explained earlier, gaming keyboards can expedite awkward or frequently used keystroke combinations.

Buying considerations

Rollover problems

Some low-quality keyboards suffer problems with rollover (that is, when multiple keys are pressed in quick succession); some types of keyboard circuitry will register a maximum number of keys at one time. Rollover is the ability of a Computer keyboard to correctly handle several simultaneous keystrokes This is undesirable for games (designed for multiple keypresses, e. A game is a structured activity, usually undertaken for Enjoyment and sometimes also used as an Educational tool g. casting a spell while holding down keys to run) and undesirable for extremely fast typing (hitting new keys before the fingers can release previous keys). A common side effect of this shortcoming is called "phantom key blocking": on some keyboards, pressing three keys simultaneously sometimes resulted in a 4th keypress being registered. Modern keyboards prevent this from happening by blocking the 3rd key in certain key combinations, but while this prevents phantom input, it also means that when two keys are depressed simultaneously, many of the other keys on the keyboard will not respond until one of the two depressed keys is lifted. With better keyboards designs, this seldom happens in office programs, but it remains a problem in games even on expensive keyboards, due to wildly different and/or configurable key/command layouts in different games.

Capital investment versus later costs

Computer input devices, including keyboards, are a good example where a bit more capital investment up front can more than pay for itself over time by reducing future costs. For example, buying an ergonomic keyboard (one with the QWERTY field divided into two sections angled away from each other) may cost $20 more up front, but if it keeps repetitive strain injury at a subclinical level rather than allowing it to progress to a level of clinical dysfunction, then it has paid for itself many times over by obviating future medical costs, user discomfort or annoyance, partial disability, etc. A repetitive strain injury (RSI also called cumulative trauma disorder ( CTD) occupational overuse syndrome, or work related upper limb disorder In Medicine, a subclinical infection refers to an inapparent asymptomatic Infection, or an infection that has such a mild course that it does not alert the Patient The same can be said of keyboards with programmable hot keys that obviate awkward keystroke combinations.

Safety Precautions

Some experts believe that the use of any keyboard may cause serious injury (that is, carpal tunnel syndrome or other repetitive strain injury) to hands, wrists, arms, neck or back. Carpal tunnel syndrome (CTS or median neuropathy at the wrist is a medical condition in which the Median nerve is compressed at the Wrist, leading A repetitive strain injury (RSI also called cumulative trauma disorder ( CTD) occupational overuse syndrome, or work related upper limb disorder Ways to reduce the risks of injuries can be done by:

1. Take frequent short breaks. Get up and walk around at least a couple of times every hour.
2. Vary your tasks throughout the day.
3. Keep your shoulders relaxed with your elbows at your side. Position your keyboard and mouse so you do not have to reach.
4. Adjust your chair and keyboard so your wrists are straight.
5. Avoid resting your wrists on sharp edges. If you use a wrist or palm rest do not use it while typing.

How it works

The following briefly describes a "dome-switch" keyboard (sometimes incorrectly referred to as a membrane keyboard), the most common type in use today:

1. When a key is pressed, it pushes down on a rubber dome sitting beneath the key. There are many types of keyboard, usually differentiated by the Switch technology employed in their operation A membrane keyboard is a Computer keyboard whose "keys" are not separate moving parts as with the majority of other keyboards but rather are Pressure pads A conductive contact on the underside of the dome touches (and hence connects) a pair of conductive lines on the circuit below. In Science and engineering, a conductor is a material which contains movable Electric charges.
2. This bridges the gap between them and allows electric current to flow (the open circuit is closed). Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. An electronic circuit is a closed path formed by the interconnection of Electronic components through which an Electric current can flow
3. A scanning signal is emitted by the chip along the pairs of lines to all the keys. When the signal in one pair becomes different, the chip generates a "make code" corresponding to the key connected to that pair of lines.
4. The code generated is sent to the computer either via a keyboard cable (using on-off electrical pulses to represent bits) or over a wireless connection. A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication Wireless communication is the transfer of information over a distance without the use of electrical conductors or " Wires quot It may be repeated.
5. A chip inside the computer receives the signal bits and decodes them into the appropriate keypress. The computer then decides what to do on the basis of the key pressed (e. g. display a character on the screen, or perform some action).
6. When the key is released, a break code (different than the make code) is sent to indicate the key is no longer pressed. If the break code is missed (e. g. due to a keyboard switch) it is possible for the keyboard controller to believe the key is pressed down when it is not, which is why pressing then releasing the key again will release the key (since another break code is sent).

Other types of keyboards function in a similar manner, the main differences being how the individual key-switches work. For more on this subject refer to the article on keyboard technology. There are many types of keyboard, usually differentiated by the Switch technology employed in their operation

Certain key presses are special, namely Ctrl-Alt-Delete and SysRq, but what makes them special is a function of software. Control-Alt-Delete (often abbreviated to Ctrl-Alt-Del, also known as the "three-finger salute" is a computer keyboard command on PC compatible systems System request (often abbreviated SysRq or Sys Req) is a key on keyboards for PCs that has no standard use In the PC architecture, the keyboard controller (the component in the computer that receives the make and break codes) sends the computer's CPU a hardware interrupt whenever a key is pressed or released. In Computing, an interrupt is an asynchronous signal from hardware indicating the need for attention or a synchronous event in software indicating the need for a change The CPU's interrupt routine which handles these interrupts usually just places the key's code in a queue, to be handled later by other code when it gets around to it, then returns to whatever the computer was doing before. The special keys cause the interrupt routine to take a different "emergency" exit instead. This more trusted route is much harder to intercept.

Customization

Sometimes it is helpful to customize the layout of a keyboard by remapping the keys. When you remap a key, you tell the computer a new meaning for the pressing of that key. Keyboard remapping is supported at a driver-level configurable within the operating system, or as add-ons to the existing programs.

For Windows, Microsoft provides a free downloadable tool called Microsoft Keyboard Layout Creator, and there are several other software programs for this purpose:

• SharpKeys: free
• KeyTweak: free

Keys on a computer keyboard

A Space-cadet keyboard has many modifier keys. The Space-cadet keyboard is a device used on MIT Lisp machines and designed by Tom Knight, which inspired several still-current jargon terms in the field

• Modifier key
  • Control key
  • Shift key
  • Alt key / Option key (Macintosh)
  • AltGr key
  • Command key / Meta key (MIT computer keyboards)
  • Windows key
  • Fn key (compact keyboard layout)
• Dead key
  • Compose key
• Lock key
  • Scroll lock
  • Num lock
  • Caps lock
• Navigation keys
  • Arrow keys
  • Page scroll keys (Page up key / Page down key)
  • Home / End key
  • Edit keys
  • Return key / Enter key
  • Backspace
  • Insert key
  • Delete key
  • Tab key
• SysRq / Print screen
• Break / Pause key
• Escape key
• Menu key
• Space bar
• Numeric keypad
• Function key
• Language input keys (on Japanese/Korean keyboards)
  • Kanji key
  • Conversion key
  • Non-conversion key
  • Half-width/Full-width key
  • Hiragana/Katakana key
  • Alphanumeric key
  • Hancha key
  • Han/Yong key
• Power management keys
  • Power key
  • Sleep key
  • Wake key
• Internet keys:
  • Internet (web browser) key. In Computing, a modifier key is a special key on a Computer keyboard that modifies the normal action of another key when the two are pressed in combination The shift key is a Modifier key on a keyboard, used to type capital letters and other alternate "upper" characters For a list of keyboard shortcuts see Table of keyboard shortcuts The Alt key on a computer keyboard is used to change (alternate the function The 'Option key' is a Modifier key present on Apple keyboards It is located between the Control key and Command key on a typical Mac keyboard AltGr is a Modifier key on PC keyboards used to type many characters primarily ones that are unusual for the locale of the Keyboard layout, such The Command key, known as the open-Apple key (as well as just "Apple" in documentation prior to the Apple Macintosh family of computers is a Modifier The Meta key was a special key on old MIT Computer keyboards such as the Space-cadet keyboard. The Windows key or Windows logo key (in short WinKey, Start key, or rarely Flag key, Go To Key (Canada or Menu Key) is Fn key can also refer to the Function keys on a Computer keyboard. QWERTY keyboardjpg|thumb|right|300px|QWERTY keyboard on a Laptop of 2007]]A keyboard layout is any specific mechanical, visual, or functional A dead key is a key on a Typewriter or a Computer keyboard that allows modification (such as by placement of Diacritic) on the following letter On some Computer systems a compose key is a key which is designated to signal the Software to interpret the next keystrokes as a combination in order to produce a Lock is a function that locks part of a keyboard keys depending on the lock settings selected Scroll lock is a key (often with an associated status light on most modern Computer keyboards The behavior of the key depends on the particular Software Num Lock is a key on the Numeric keypad of most Computer keyboards used to switch the pad between number entry and arrow keys The caps lock is a key on a Computer keyboard. Pressing it will set a keyboard mode in which typed letters are capitalized by default and (on some computers Cursor movement keys or arrow keys are buttons on a Computer keyboard that are either programmed or designated to move the cursor in a specified direction The Page Up and Page Down keys are two keys commonly found on Computer keyboards The two keys are primarily used to scroll up or down in documents but the scrolling The Page Up and Page Down keys are two keys commonly found on Computer keyboards The two keys are primarily used to scroll up or down in documents but the scrolling The Page Up and Page Down keys are two keys commonly found on Computer keyboards The two keys are primarily used to scroll up or down in documents but the scrolling Home keys can also refer to Home row in typing The home key is a key commonly found on Computer keyboards The key works the opposite The end key is a key commonly found on Computer keyboards This key performs the opposite effect of the Home key. In Computer keyboards the enter key (or the return key) in most cases causes a command line, window form or Dialog box to operate Backspace is the keyboard key that originally pushed the Typewriter carriage one position backwards and in modern computer displays moves the cursor one position backwards The Insert key (often abbreviated INS) is a key commonly found on Computer keyboards It is primarily used to switch between the two text-entering modes on The delete key, known less ambiguously as forward delete, Del, or ⌦, performs a function when struck on a Computer Tab key (abbreviation of tabulator key) on a keyboard is used to advance the cursor to the next Tab stop. System request (often abbreviated SysRq or Sys Req) is a key on keyboards for PCs that has no standard use Print screen (often abbreviated Prt Scr, Print Scrn, Prt Scn, Prt Sc or Prnt Scrn) is a key present on most keyboards The break key on Computer keyboards no longer has a well-defined purpose The break key on Computer keyboards no longer has a well-defined purpose The Esc key is a key labeled Esc or Escape that is used to generate the ASCII Escape character ( Control - ASCII code In computing the Menu key or Application key is a key found on Windows-oriented computer keyboards The space bar, spacebar, or space key, is a key on an Alphanumeric keyboard in the form of a horizontal bar in the lowermost row significantly wider A numeric keypad, or numpad for short is the small palm-sized seventeen key section of a Computer keyboard, usually on the very far right A function key is a key on a Computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application Language input keys are keys designed to translate letters entered by users usually found on Japanese and Korean keyboards for use with an Input method editor QWERTY keyboardjpg|thumb|right|300px|QWERTY keyboard on a Laptop of 2007]]A keyboard layout is any specific mechanical, visual, or functional The power management keys are three keys on 108 key PC computer keyboards which control the Computer 's Power management status The power management keys are three keys on 108 key PC computer keyboards which control the Computer 's Power management status The power management keys are three keys on 108 key PC computer keyboards which control the Computer 's Power management status The power management keys are three keys on 108 key PC computer keyboards which control the Computer 's Power management status
  • E-mail
• Multimedia keys:
  • Volume keys or wheel (+/-/mute). Electronic mail, often abbreviated to e-mail, email, or originally eMail, is a Store-and-forward method of writing sending receiving Silence is a relative or total lack of audible Sound you can not hear a thing it is quiet

See also

Projection keyboard

For European (AZERTY etc) and other layouts see Keyboard layout

• Ergonomics
• Repetitive strain injury
• Keyboard styles
  • Alphanumeric keyboard
  • Enhanced keyboard
    • AT keyboard
  • Velotype (chorded keyboard)
  • Virtual keyboard
  • Optimus Maximus keyboard
  • Das Keyboard (blank keyboard)

• "fixed split keyboard" and "adjustable split keyboard" with a larger gap between the "left hand keys" and the "right hand keys"
  • EZ-Reach (keyboard)
  • Microsoft Natural keyboard
  • Maltron keyboard
  • Kinesis keyboard
  • Datahand (featuring joystick-like buttons to reduce finger movement)

• Keyboard layout
  • Dvorak keyboard
  • British and American keyboards

• Keyboard technology
  • Membrane keyboard
  • Chiclet keyboard
  • Buckling spring

• Apple Keyboard
• ASCII
• ASDF (sequence of letters)
• British and American keyboards
• Chinese input methods for computers
• Chord keyset
• F-Lock
• GKOS keyboard (chorded keyboard)
• IBM PC keyboard
• Lighted Program Function Keyboard
• Model M Keyboard
• Overlay keyboard
• Space-cadet keyboard
• Touch typing
• Typing
• Hunt and peck typing
• Home row
• Key jamming
• Rollover (key)
• QWERTY and accents
• Table of keyboard shortcuts
• Happy Hacking Keyboard
• Das Keyboard
• FrogPad

References regarding problems with keypresses in short succession:

• http://forums.logitech.com/logitech/board/message?board.id=hardware&thread.id=991
• http://ask.metafilter.com/51940/Whats-a-brand-of-keyboard-that-allow-multiple-keys-to-be-pressed

References

External links

How Computer Keyboards Work at HowStuffWorks

• Zupera Technology - Manufacturer of Industrial / Kiosk Keyboards
• Ghost key detection
• Large searchable database of keyboard shortcuts at Keyxl.com
• Mac OS X Keyboard Shortcuts
• Apple Keyboard Symbols
• Mac OS X Keystrokes Guide @ MiniGuidez.com
• Keyboard Help — Typing world language accent marks and other diacritics with your keyboard.
• FITALY stylus/one-finger rapid input keyboard for mobile devices

IBM/Windows keyboard (US layout) v • d • e
Esc		F1	F2	F3	F4		F5	F6	F7	F8		F9	F10	F11	F12		PrtSc	ScrLk	Pause
																	Ins	Home	PgUp		NumLk	/	*	-
																	Del	End	PgDn		7	8	9	+
																					4	5	6
																		↑			1	2	3	Ent
																	←	↓	→		0		.