Input devices are categorized into devices that use media input and interactive input devices. Media input devices include paper tape input machines, card input machines, scanners, optical character readers (OCR), optical mark readers (OMR), IC card readers, magnetic card readers, barcode readers, tape drives, floppy disk drives, optical disk drives, and so on.
These devices feed information recorded on a variety of media (e.g., perforated paper tape, perforated cards, paper, magnetic tapes, floppy disks, optical disks) into the computer. Interactive input devices include keyboards, light pens, mousers, touch screens, tracking balls, and control sticks. Input is made by means of a dialog between the user and the computer, and the input and the computer's response can be seen on the monitor's screen.
Since the 1990s, handwritten Chinese character recognition devices and handwritten Chinese character input devices have become practical, research on speech input devices has also reached a certain level, and digital cameras as image input devices have begun to spread. A keyboard is an input device consisting of keys. Users input programs, commands, and data to the computer by striking keys. The number of keys on a keyboard varies depending on the requirements of use. Each key position of the keyboard has a key switch, which serves to detect the keystroke action and convert the mechanical displacement into an electrical signal. The key switches are arranged in an m x n matrix, i.e. each key switch has a fixed position on the m x n matrix.