Keyboard

In computing, a keyboard is a peripheral partially modeled after the typewriter keyboard

Physically, a keyboard is an arrangement of buttons, or keys. 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 . 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. Other keys can produce actions when pressed, and other actions are available by the simultaneous pressing of more than one action key.

Keyboard layouts

There exists a large number of different arrangements of symbols on keys. 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.

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. 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. 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 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. 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.

Connection types

There are several different ways of connecting a keyboard which have evolved over the years. These include the standard AT connector commonly found on motherboards, which was eventually replaced by the PS/2 and USB connection. Prior to the iMac line of systems, used [[Apple Desktop Busa proprietary system, for its keyboard connector.

Wireless types

Wireless keyboards have become popular for their increased user freedom. However, a wireless keyboard needs batteries to work and may pose a security problem due to the risk of eavesdropping.

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. A wireless keyboard may use an industry standard RF, called Bluetooth. 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. 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. Many typists prefer the buckling spring board, which is still manufactured.

Alternatives to the "regular" keyboard

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. It is very popular with videographers who have to spend hours editing their raw video. 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. There is no reason why other applications such as word processing and email programs cannot take advantage of specialty keyboards' shortcut keycaps.

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 keyed, i.e. pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. Other two-handed alternatives more akin to a game controller, such as the Alpha Grip, are also used as a way to input data and text.

Another way to reduce the size of a keyboard is to use smaller buttons and pack them closer together. Such keyboards, often called a "thumb board" (thumbing) are used in some personal digital assistants such as the Treo and BlackBerry and some Ultra-Mobile PCs .

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.

aming keyboards

Some gaming keyboards offer extra function keys which can be programmed with keystroke macros. 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 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.

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. Sensors in the projection unit identify which key is being "pressed" and relay the signals to a computer or personal digital assistant.

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. The fastest keyboard so far is the stenotype — some people who use a stenotype type faster than 300 words per minute