Input Device Facts
Common interfaces used for connecting input devices include: * 6-pin mini-DIN (PS/2 connector) for keyboard and mouse * USB for keyboard, mouse, and other devices * Infrared and wireless connections for keyboards, mouse, and other devices * DB-9 (serial) connector for specialized input devices
The following table lists several considerations for selecting input devices. Device Type | Considerations | Keyboard | Keyboards typically connect through a PS/2 or USB port. Many keyboards include special function keys that simplify playing music or browsing the Web. Some keyboards include a built-in USB port that can be used to connect other peripheral devices. | Mouse | A mouse typically connects through a PS/2 or USB port. A wireless mouse typically transmits to a receiving station attached through a USB port. * Mechanical mice use a roller ball to detect motion. The roller ball must be cleaned periodically to ensure proper functionality. * Optical mice use light rays to detect motion. Optical mice require less maintenance than mechanical mice. * Motion-based mice can accurately detect mouse movement while in the air. This particular device can attach to a user's head and moves the cursor when the head moves. * You can select mice with multiple additional buttons or a scroll wheel to add functionality. * A trackball is a pointing device that is like an upside-down mechanical mouse where the user manipulates the pointer by rolling the ball. | Touchscreen | A touchscreen is a special monitor that allows input by tapping or writing with a stylus or fingers. Touchscreens are used in kiosks and portable devices such as PDAs and Tablet PCs. There are three basic types of touchscreens: * A capacitive screen uses a thin electrically charged layer placed over the monitor screen. When touched, the charge moves from the capacitive surface to the touching object. The screen location of the touch is calculated and sent to the computer. This method blocks some of the light emanating from the monitor. * A resistive screen uses a glass panel covered with two metallic layers (one conductive and the other resistive) separated by a very narrow gap and mounted over the monitor screen. A protective layer is applied to the touch surface. When the screen is touched, the two metallic layers make contact and that location is calculated. This type of touchscreen also blocks some of the monitor's light emanation. * A surface acoustic wave screen places tiny matching transducers across the screen surface from each other (one to send and the other to receive). When an object touches the screen surface, the signal is interrupted and that location is then calculated. This type of touchscreen does not visually impair the monitor. | Barcode reader | A barcode reader is a device that can scan barcodes. * Barcodes are most commonly used in retail environments at checkout stands. Shipping companies, hospitals, and other organizations use barcodes to track or inventory objects. * Most bar code readers use a laser to scan the barcode, although some do use cameras or optical scanners. * Older readers used a serial interface, while newer readers use USB or PS/2. * Barcode readers include software that interprets the meaning of the barcode. | KVM switch | A KVM (keyboard, video, mouse) switch allows you to connect multiple PCs to a single set of input/output devices. KVM switches have multiple input groups, with each group accepting keyboard, video, and mouse connections from a single computer. A single output group connects to the shared input/output devices. Buttons on the KVM switch or keyboard shortcut combinations allow you to toggle the input/output devices between computers. * KVM switches are typically used in a data center where you manage multiple computers from a single central console. * Local KVM switches must be within about 5 meters of the connected computers. * Networked or remote KVM switches use special hardware devices that send keyboard, mouse, and video content through a network connection. |