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Chapter 7 - Storage. By Chris Wilson. Storage. Holds data, instructions, and information for future use. Storage Medium (secondary storage) – The physical material on which a computer holds data. Ex: floppy disks, hard disks, CDs, DVDs, tape, ZIP disks, PC cards.
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Chapter 7 - Storage By Chris Wilson
Storage • Holds data, instructions, and information for future use. • Storage Medium(secondary storage) – The physical material on which a computer holds data. Ex: floppy disks, hard disks, CDs, DVDs, tape, ZIP disks, PC cards. • Capacity – Number of bytes a storage medium can hold.
Storage Device • The computer hardware that records and/or retrieves items to and from storage media. • Writing – process of transferring data to a storage medium • Reading – process of transferring these items from a storage medium into memory. • Access time – amount of time it takes a storage device to locate an item on a storage medium.
Floppy Disks • Floppy Disk(diskette) – A portable storage medium that consists of a thin, circular, flexible plastic Mylar film in a square plastic shell. • Magnetic media – Uses magnetic particles to store items in tracks and sectors. • Tracks – narrow recording band that forms a full circle on the disk • Sector – arc shaped storage locations that make the tracks.
ZIP Disk • ZIP disk – A type of portable magnetic media that can store up to 500 times more than a standard floppy.
Hard Disk • Hard Disk(hard disk drive) – A storage device that contains one or more inflexible, circular platters that store data, instructions, and information. • Platter – A 3.5 or 5.25in disk made of aluminum, glass, or ceramic and is coated with an alloy material that allows items to be recorded magnetically on it’s surface.
How a Hard Disk Works • A platter will spin around at a rate of 5,400-7,200rpms, while a reader/writer head floats above the platter at ~two millionths of an inch. • Cache – location where frequently used items are store to improve efficiency.
Types of Hard Disks • Internal – Permanently inside the CPU. • External – A separate freestanding hard disk that connects with a cable to a USB port.
Internet Hard Drives • Internet Hard Drive – a service on the web that provides storage to computer users, usually for a minimal fee. • Allows users to to access files from any computer of device that has Internet access.
CDs and DVDs • CDs and DVDs – storage media that consists of a flat, round, portable metal disc with a protective plastic coating. • An optical media that stores items by using microscopic pits (indentations) and lands (flat areas) • A high –powered laser light creates the pits, and a lower-powered laser reads items by reflecting light through the bottom of the disc.
CD-ROMs and CD-RWs • CD-ROM – Optical disc that holds from 650MB to 1 GB of data. Users can read information from these discs but can not modify them. • CD-R (compact disc-recordable) – A multisession disc that users can record their own information once only • CD-RW(compact disc-rewritable) – A disc in which users can write, and then re-write new information.
DVD-ROM and DVD+RWs • DVD-ROM(digital versatile disc-ROM or digital video disc) – an extremely high capacity optical disk capable of storing from 4.7 GB to 17 GB. • DVD+RW – A recordable version of DVD that allows users to erase and record more than 1,000 times.
Tape • Tape – a magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost. • Tape drive – Device that reads and writes data and information on tape.
PC Cards and Types of Miniature Storage Media • PC Card – A thin credit-card sized device that fits into a PC Card slot to add storage or other capabilities to a desktop or notebook computer. • Examples: PDA;s, digital cameras, music plaers. • Miniature mobile storage media – Compact flash, Memory stick, Secure digital, Smart Media.
Microfilm and Microfiche • Microfilm – A 100-215ft roll of film used to store back issues of newspapers, magazines, and records. • Microfiche – A small sheet of film usually about 4 by six inches used in the same fashion as microfilm.