Class 3 Components. PeripheralsThere are 7 components which allow humans to interface with computers. Three of them you have studied during your previous lessons, they are printers, modems and scanners. Display devices include computer monitors and other display devices. CRTs and LCDs are common. LCDs are a more recent development, and will replace CRTs as they become more affordable. LCD’s in addition to being lighter also use less energy and generate less heat. Sound Output includes internal or external speakers and headphones. Mouse is a user interface device that can enable different kinds of control than a keyboard, particularly in GUIs. Most mice (sometimes the plural is ‘mouses’ to prevent confusion with the rodent) are made from plastic, and may use a ball to track movement, an LED light, or a laser. Today you can get a wireless mouse that allows you to easily give a presentation with out being tied to a desk. And the track ball can be used as just as the optical mouse. A k eyboard is an input device which is connected to a computer and used to type instructions or information into the computer. The keyboards sold have 101 to 106 individual keys. Keyboards differ between languages. Most English-speaking people use what is called a QWERTY layout. This refers to the order of the top row of keys. Some foreign languages (i. e. German) use QWERTZ, where the Z and Y are switched. Many laptop computers do not include a number pad. Modern keyboards sometimes have extra controls such as volume, and keys that can be programmed to bring up programs of the user’s choice. The keyboards hook up to the computer with PS/2 or USB connector.
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