Alphanumeric keyboard
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Alphanumeric keyboards include typewriters and computer keyboards. An alphanumeric keyboard is a device with many keys (usually marked with the letters of the alphabet, the numerical digits, and various extra keys.)
After punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers. During the 1980s and 1990s almost all computers came equipped with them as the main form of interaction, and most users are familiar with using them.
There are different types of keyboard technologies.
The layout of keys on the modern-day English keyboard is called the QWERTY design, based on the most popular typewriter keyboard layout. This has been further extended to the standard 104-key PC keyboard layout, with the addition of cursor keys, a calculator-style numeric keypad, two groups of special function keys, a key for the Windows menu (on IBM and clones), and other modifier keys. Some computer manufacturers have added keys specifically related to the Internet and e-mail, but these have not become standard.
There is another kind of computer keyboard known as a chorded keyboard. These are rarely used.
Despite the development of alternative input devices such as the mouse, touch sensitive screens, pen devices, character recognition, voice recognition, and improvements in computer speed and memory size, the keyboard remains the most commonly used and most versatile device used for direct human input into computers.