Keyboard

Although most of today’s personal computers feature a point-and-click graphical interface (see and mouse) the keyboard remains the main means for entering text and other data into computer applications. The modern computer keyboard traces its ancestry to the typewriter, and the layout of its alphabetic and punctuation keys remains that devised by typewriter pioneer Christo-pher Latham Sholes in the late 1860s.

The principal difference in operation is that while a typewriter needs only to transfer the impression of a key through a ribbon onto a piece of paper, the computer key-board must generate an electrical signal that uniquely iden-tifies each key. This technology dates back to the 1920s with the adoption of the teletypewriter (often known by the brand name Teletype), which allowed operators to type text at a keyboard and send it over telephone lines to be printed. The transmissions used the Baudot character code, which used five binary (off or on) positions to encode let-ters and characters. This gave way to the ASCII code in the 1960s (see characters and strings) at about the time that remote time-sharing services allowed users to interact with computers through a Teletype connection.

The modern personal computer keyboard was standard-ized in the mid-1980s when IBM released the PC AT. This expanded keyboard now has 101 or 102 keys. It supplements the standard typewriter keys with cursor-control (arrow) keys, scroll control keys (such as Page Up and Page Down), a dozen function keys that can be assigned to commands by software, and a separate calculator-style keyboard for numeric data entry. During the 1990s, Microsoft introduced a few extra keys for Windows-specific functions.

The advent of laptop (or notebook) computers required some compromises. The keys are generally smaller, although on the better units they are still far enough apart to allow for comfortable touch-typing. Laptops often combine the function keys and cursor control keys with the regular keys, using a special “Fn” key to shift between them.

In recent years, there has been some interest in adopt-ing an alternative key layout devised by August Dvorak in the 1950s. The theory behind this layout was that arrang-ing the keyboard so the most commonly used keys were directly under the fingers would be more efficient than the Sholes layout, which legend claims was devised primarily to slow down typists to a speed that early typewriters could handle without jamming. However, researchers have gener-ally been unable to find a significant improvement in either performance or ergonomics between use of the standard and Dvorak layouts, and the latter has not caught on com-mercially. Concern with repetitive strain injury (RSI) has led to experiments in designing a keyboard more suited to the human wrist and hand (see ergonomics of computing). Some designs such as the Microsoft Natural Keyboard divide the layout into left and right banks of keys and angle them toward one another to reduce strain on the wrists. An extreme form of the design actually breaks the keyboard into two pieces. Such extreme designs have not found wide acceptance.

It is possible that the further development of voice rec-ognition software might allow spoken dictation to supplant the keyboard for data entry. Currently, however, such tech-nology is limited in speed and accuracy (see speech recog-nition and synthesis).

With the increasingly popular mobile devices (see pda and smartphone), keyboards are sometimes dispensed with entirely. For light data entry (such as for e-mail and text messaging), a small version of the standard keyboard can be used. (In such cases users can type with their thumbs.) With touch-sensitive screens on mobile devices, a “virtual keyboard” can be displayed on the screen; however, the lack of tactile feedback means this data-entry method takes some getting used to. One can also obtain a keyboard that can wirelessly connect to such a device to allow for more extensive data entry (see Bluetooth.)