Review of Storage, Display and Input Devices Written by: Andrea LeShea Georgia CTAE Resource Network 2010 Storage Devices Used to keep data when the power to the computer is turned off. Medium/media Location where data is stored. Hard Disk Usually mounted inside the computer’s system unit. Magnetic Storage Recording of data onto disks or tape by magnetizing particles of an oxide based surface coating. Floppy Disk Round piece of flexible Mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective covering May be referred to as a “floppy” 3½ disk capacity is 1.44 MB or 1,440,000 bytes Optical Storage Means of recording data as light and dark spots on CD or DVD. Reading is done through a low-power laser light. Pits Dark spots Lands Lighter, non-spotted surface areas CD-ROM “CD – Read Only Memory” Also called CD-R CD-Read Storage device that uses laser technology to read data that is permanently stored on compact disks, cannot be used to write data to a disk. CD-RW “CD-Read Write” A storage device that reads data from CD’s and also can write data to CD’s. Similar to a CD-ROM, but has the ability to write to CD. DVD DVD ROM Digital Video Disk which is read only. DVD-R Digital Video Disk which can be written to one time. It then becomes read only. DVD-RW Digital Video Disk which can be rewritten to. Blu-Ray Technology New standard in storage Blu-Ray New disks use blue laser light instead of the red laser light used in traditional CD players. Disks may ultimately hold Over 30GB on one-sided disks. Over 50GB on two-sided disks. Flash or Jump Drives External storage devices that can be used like a external hard drive. They have the capability to be saved to, deleted from, and files can be renamed just like with a normal hard drive. List of Devices for Secondary Storage Magnetic tape and disks Compact Disk Read-Only Memory (CD-ROM) Write Once Read Many - (WORM) Magneto-optical disks Redundant Array of Inexpensive Disks (RAID) Optical disks Digital Video Disks Memory cards Flash memory Removable storage Monitor Overview Display device that forms an image by converting electronic signals from the computer into points of colored light on the screen. The most-used output device on a computer. Most desktop displays use a cathode ray tube (CRT). Laptops use liquid crystal display (LCD), lightemitting diode (LED), and gas plasma or other image projection technology. Monitors using LCD technologies are beginning to replace CRT. LCD Technology Used for displays in notebooks, small computers, pagers, phones and other instruments. Uses a combination of fluorescent-based backlight, color filters, transistors, and liquid crystal to create and illuminate images. In 1997, manufactures began to offer full size LCD monitors as alternatives to CRT monitors. Until recently, was only used on notebook computers and other portable devices. How Monitors Work Most use a cathode-ray tube as a display device. CRT: Glass tube that is narrow at one end and opens to a flat screen at the other end. Narrow end contains electron guns. Single gun for monochrome and three guns for color. Display screen is covered with tiny phosphor dots that emit light when struck by the electron gun. Monitor Quality, Resolution and Pixels Quality: Manufacturers describe quality by dot pitch. Smaller dot pitches mean pixels are closely spaced which will yield a sharper image. Resolution: Indicates how densely packed the pixels are. The amount of Pixels on the screen. The more pixels the better the resolution. Pixels: The smallest unit in a graphic image; computer display devices use a matrix of pixels to display text and graphics. Input Devices Units that gather information and transform that information into a series of electronic signals for the computer. Mouse An input device that allows the user to manipulate objects on the screen by moving the mouse along the surface of the desk. Keyboard An arrangement of letters, numbers, and special function keys that act as the primary input device to the computer. Scanner Light sensing input device that reads printed text and graphics and then translates the results into a form the computer can process. Allows users to capture data from an original source document and save in an electronic format. Touch Screen A touch sensitive display device that allows users to interact with devices by touching various areas of the screen. Examples of Touch Screens: Smart Phones Airport Check-In Kiosk Grocery Store Self Check Out ATM’s Barcode Reader A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Pointing Device An input device that allows a user to control a pointer on the screen. The location and shape change as the user moves the pointing device. Pointing Devices Include: Mouse Trackball Touchpad Digital Camera Allows users to take pictures and store images electronically. Smart Phone A small hand held device that users can enter data and instructions using a variety of techniques. References Computing Essentials 2005 M. Guymon. Pleasant Grove High School