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Chapter 7 Storage

Chapter 7 Storage. Chapter 7 Objectives. Discuss the various types of items that users store on computer media. Describe the characteristics of CDs and DVDs. Differentiate between storage devices and storage media. Differentiate among CD-ROMs, CD-RWs, DVD-ROMs, and DVD+RWs.

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Chapter 7 Storage

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  1. Chapter 7Storage

  2. Chapter 7 Objectives Discuss the various types of items that users store on computer media Describe the characteristics ofCDs and DVDs Differentiate between storage devicesand storage media Differentiate among CD-ROMs,CD-RWs, DVD-ROMs, and DVD+RWs Describe the characteristics ofa floppy disk drive Identify the uses of tape Identify the uses of Zip disks Discuss PC Cards and the various typesof miniature storage media Describe the characteristics ofa hard disk Identify uses of microfilm and microfiche Identify the advantages of usingan Internet hard drive

  3. MEMORY VERSUS STORAGE • Memory • Fast • Short term • RAM is Volatile • Holds the current program and its data

  4. MEMORY VERSUS STORAGE • Storage • Slower • Long term • Nonvolatile • Stores programs and data for future use • Can be thought of as both input and output device • Input: read data from storage into memory • Output: transfer data from memory to storage

  5. MEMORY VERSUS STORAGE • Storage Capacity: how many bytes (characters) a storage medium can hold • Kilobyte (KB) = 1 thousand (1,000) • Megabyte (MB) = 1 million (1,000,000) • Gigabyte (GB) = 1 billion (1,000,000,000) • Terabyte (TB) = 1 trillion (1,000,000,000,000) • Petabyte (PB) = 1 quadrillion (1,000,000,000,000,000) • Exabyte (EB) = 1 quintillion (1,000,000,000,000,000,000)

  6. Stores … Primary Storage Memory (most RAM) Items waiting to be interpretedand executed by the processor Secondary Storage Hard Disk Operating system, applicationsoftware, user data and information CDs and DVDs Software, backups, movies, music Miniature Storage Media Digital pictures or small files tobe transported Tape Backups Floppy Disk Small files to be transported STORAGE • What is access time? • Time it take storage device to locate and retrieve an item. fastertransferrates slowertransferrates

  7. FLOPPY DISKS • Characteristics of a Floppy Disk • Magnetic • Size • 3.5-inch, 5.25-inch • Anatomy • Shutter • Shell • Liner • Disk • Hub • Write-protect notch

  8. FLOPPY DISKS • Characteristics of a Floppy Disk • Formatting: preparing a floppy disk for use • Track • Sector • Cluster • Capacity = sides x tracks x sectors per track x bytes per sector • File allocation table (FAT) How the Floppy Drive Works

  9. Zip disk FLOPPY DISKS • Zip Disks • 100 MB to 750 MB • The larger ones areequivalent to about500 diskettes! • Require a zip drive

  10. HARD DISKS • Primary media for storing software programs and files • Up to 160 GB capacity and more on PC hard disk • Consists of several platters

  11. Sample Hard Disk Characteristics Advertised capacity 40 GB Platters 2 Read/write heads 4 Cylinders 16,383 Bytes per second 512 Sectors per track 63 Sectors per drive 78,165,360 Revolutions per minute 7,200 Transfer rate 100 MB per second Access time 9 ms HARD DISKS • Characteristics of a Hard Disk actualdiskcapacity

  12. Clearance is approximately two millionths of an inch HARD DISKS • How a Hard Disk Works • Arms move read/write heads to proper location on the platters • Read/write head floats above platter • How it Works hair read/write head dust smoke gap platter

  13. cylinder track HARD DISKS • How a Hard Disk Works • Cylinder: location of a single track through all platters • Disk cache improves performance • Partitions function as separate drives

  14. HARD DISKS • External Hard Disks • Capacities up to 250 GB or more • Removable Hard Disks • Large storage capacity (60 GB or more) • Easily transported • Iomega’s Peerless disk (up to 40 GB) • USB Portable Drives • Capacity up to 1 GB • Fit on a key chain

  15. HARD DISKS • RAID • Redundant array of independent disks • Increased reliability through redundancy • Expensive • Many levels of RAID • Mirroring • Striping

  16. file 1 after defrag disk after defragmentation process HARD DISKS • Maintaining Data Stored on a Hard Disk • Preventative maintenance • Backup • Defragmentation

  17. HARD DISKS • Internet Hard Drive (Online Storage) • Service on the web that provides storage to computer users • Fee usually involved • Iomega’s iStorage

  18. Disc sectors Single track spirals to edge of disc CDs and DVDs • Used to distribute software packages • Uses a laser beam to read and write data • Stores items in spiraling tracks • Sectors are all the same size

  19. CDs and DVDs • CD-ROM • Compact disc read-only memory • Cannot be erased or modified • Can contain text, graphics, and video as well as sound • Capacity: about 650 MB = 450 diskettes to 1GB • CD-ROM drive speed How the CD-ROM Works

  20. CDs and DVDs • Writable CDs • CD-R (compact disc-recordable) • Multisession • Can read/write audio CDs and standard CD-ROMs • CD-ROM drives can usually read CD-R • CD-RW (compact disc-rewritable) • Erasable • Can read any format CD • Older CD-ROM drives can’t read them • Photo CD

  21. CDs and DVDs • DVD-ROM (Digital versatile disc-ROM or Digital Video Disc-ROM) • Can hold much more data than CD-ROMs • 4.7 GB to 17 GB • Higher quality than CD-ROMs • Often used for video

  22. CDs and DVDs • DVD variations • Digital movies and audio • DVD-R is single-session recordable • DVD+RW is rewritable

  23. MAGNETIC TAPES • Cost effective way to store large amounts of infrequently used data • Types: • Reel-to-reel on older systems • Tape cartridge • Access technique: • Sequential access (tapes) • Direct access (floppy disks, hard disks, CDs, DVDs)

  24. PC CARDS • Thin, credit card-sized device that fits into a PC Card expansion slot of laptop • Add storage, memory, communications, and sound capabilities

  25. OTHER TYPES OF STORAGE • Smart Cards • Similar in size to credit card or ATM card • Has an embedded microprocessor • Types: • Intelligent (with a microprocessor) • Memory card (storage only, as with a digital camera) • Prepaid smart cards • Electronic money

  26. Media Life Expectancies Media Type Guaranteed Life Potential Life Expectancy Expectancy Magnetic disks 3 to 5 years 20 to 30 years CDs and DVDs discs 5 to 10 years 50 to 100 years Microfilm 100 years 500 years OTHER TYPES OF STORAGE • Microfilm and Microfiche • Stores microscopic images of documents on roll or sheet film • Often used by libraries and banks due to length of life

  27. Chapter 7 Complete

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