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Chapter 7 Storage

Chapter 7 Storage. Chapter 7 Objectives. Next. Differentiate between storage devices and storage media. Differentiate among CD-ROMs, recordable CDs, rewritable CDs, DVD-ROMs, recordable DVDs, and rewritable DVDs. Describe the characteristics of magnetic disks. Identify the uses of tape.

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Chapter 7 Storage

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  1. Chapter 7Storage

  2. Chapter 7 Objectives Next Differentiate between storage devicesand storage media Differentiate among CD-ROMs,recordable CDs, rewritable CDs, DVD-ROMs, recordable DVDs, and rewritable DVDs Describe the characteristics ofmagnetic disks Identify the uses of tape Differentiate between floppy disks and Zip disks Discuss PC Cards and the various typesof miniature mobile storage media Describe the characteristics ofa hard disk Identify uses of microfilm and microfiche Describe the characteristics of optical discs

  3. Storage Next • What isstorage? • Holds data, instructions, and information for future use • Storage mediumis physical material used for storage • Also called secondary storage p. 354 Fig. 7-1

  4. Storage Kilobyte (KB) 1 thousand Megabyte (MB) 1 million Gigabyte (GB) 1 billion Terabyte (TB) 1 trillion Petabyte (PB) 1 quadrillion Exabyte (EB) 1 quintillion Zettabyte (ZB) 1 sextillion Yottabyte (YB) 1 septillion Next • What iscapacity? • Number of bytes (characters) a storage medium can hold p. 356

  5. Storage Memory(most RAM)(chips on motherboard) Screen Display Storage Medium(floppy disks, Zip disks,hard disks, CDs) Next • How does volatility compare? • Storage medium is nonvolatile—contents retained when power is off • Memory is volatile—holds data and instructions temporarily ON OFF Display appears Display disappears Volatile Data andinstructions available to user Data and instructions erased Contents available to user Contents retained Nonvolatile p. 356

  6. Storage Functions as source of input Creates output Next • What is astorage device? Hardware that records and retrieves items to and from storage media Reading Process of transferring items from storage media to memory Writing Process of transferring items from memory to storage media p. 356

  7. Storage 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 Flash Memory Cards and USB Flash Drives Digital pictures or files to be transported CDs and DVDs Software, backups, movies, music Tape Backups Floppy Disk Small files to be transported Next • What isaccess time? • Time it takes storage device to locate item on storage medium • Time required to deliver item from memory to processor fastertransferrates slowertransferrates p. 357 Fig. 7-4

  8. Magnetic Disks Trackis narrow recording bandthat forms fullcircle on disk Sectorstores up to512 bytesof data Next • What aretracks andsectors? Formatting prepares disk for use and marks bad sectors as unusable p. 357 Fig. 7-5

  9. Magnetic Disks Next • What is afloppy disk? shutter • Portable, inexpensive storage medium (also called diskette) shell liner magneticcoating Thin, circular, flexible film enclosedin 3.5” wide plastic shell metal hub flexible thin film p. 358

  10. Magnetic Disks Next • What is afloppy disk drive? • Device that reads from andwrites to floppy disk Floppy disk drive built intoa desktop computer • One floppy drive, named drive A • Also called secondary storage External floppy disk drive attaches toa computer with a cable p. 358 Fig. 7-6

  11. Magnetic Disks Capacity: 1.44 MB Sides: 2 Tracks: 80 Sectors per track: 18 Bytes per sector: 512 Sectors per disk: 2880 Next • How do you compute a disk’s storage capacity? • Multiply number of sides, number of tracks, number of sectors per track, and number of bytes per sector • For high-density disk: 2 sides  80 tracks  18 sectors per track  512 bytes per sector = 1,474,560 bytes Characteristics of a3.5-inch High-DensityFloppy Disk p. 359

  12. Magnetic Disks write-protected notch openmeans youcannot writeon the disk not write-protected hole on thisside meansdisk is highdensity notch closedmeans youcan write onthe disk Next • What is awrite-protect notch? • Small opening with a cover that you slide • Protects floppy disk from being erased accidentally p. 359 Fig. 7-7

  13. Magnetic Disks Next • What is aZip disk? • Magnetic medium that stores 100 MB to 750 MB of data • Used to back up and to transfer files • Backup is duplicate of file, program, or disk in case original is lost • Zip disks require aZip drivec—chigh capacity drive that reads from and writes on a Zip disk c p. 359 Fig. 7-9

  14. Magnetic Disks Next hard disk installedin system unit • What is ahard disk? • High-capacity storage • Consists of several inflexible, circular platters that store items magnetically • Components enclosed in airtight, sealed case for protection p. 360 Fig. 7-10

  15. Magnetic Disks Sample Hard Disk Characteristics Advertised capacity 120 GB Platters 3 Read/write heads 6 Cylinders 16,383 Bytes per second 512 Sectors per track 63 Sectors per drive 234,441,648 Revolutions per minute 7,200 Transfer rate 133 MB per second Access time 8.9 ms Next • What are characteristics of a hard disk? actualdiskcapacity p. 361 Fig. 7-11

  16. Magnetic Disks Next • How does a hard disk work? Step 3.When software requests a disk access, read/write heads determine current or new location of data. Step 2.Small motor spins platters while computer is running. Step 4.Head actuator positions read/write head arms over correct location on platters to read or write data. Step 1.Circuit board controls movement of head actuator and a small motor. p. 361 Fig. 7-12

  17. Magnetic Disks Next platter • What is acylinder? track • Vertical section of track through all platters sector • Single movement of read/write head arms accesses all plattersin cylinder read/writehead platter sides p. 362 Fig. 7-13 cylinder

  18. Magnetic Disks Next • What is ahead crash? • Occurs when read/write head touches platter surface • Spinning creates cushion of air that floats read/write head above platter • Clearance between head and platter is approximately two-millionths of an inch • A smoke particle, dust particle, or human hair could render drive unusable hair read/write head dust clearance smoke platter p. 362 Fig. 7-14

  19. Magnetic Disks processor disk cache first requestfor data—to disk cache second requestfor data—to hard disk hard disk Next • What is adisk cache? • Portion of memory that processor uses to store frequently accessed items p. 363 Fig. 7-15

  20. Magnetic Disks Next • What is aminiature hard disk? • Provide users with greater storage capacities than flash memory • Some have a form factor of less than 1 inch • Storage capacities range from 2 GB to 100 GB p. 363 Fig. 7-16

  21. Magnetic Disks Next • What areexternal hard disksandremovable hard disks? • Used to back up or transfer files Removable hard disk—hard diskthat you insert and removefrom hard disk drive External hard disk—freestandinghard disk that connects to system unit p. 364 Fig. 7-17

  22. Magnetic Disks SATA (Serial Advanced Technology Attachment) controller uses serial signals to transfer data, instructions, and information EIDE (EnhancedIntegratedDrive Electronics) controller supports four hard disks, provides connections for CD and DVD drives Chip and circuits that control transfer of items from disk SCSI(SmallComputerSystemInterface)controller supports up to fifteendevices including hard disks, CDand DVD drives, tape drives, printers,scanners, network cards Next • What is adisk controller? p. 364

  23. Magnetic Disks Next • What is online storage? • Service on Web that provides storage for minimal monthly fee • Files can be accessed from any computer with Web access • Large files can be downloaded instantaneously • Others can be authorized to access your data p. 365 Fig. 7-18

  24. Optical Discs Next • What areoptical discs? Push the button toslide out the tray. • Flat, round, portable metal discs made of metal, plastic, and lacquer • Can be read only or read/write Insert the disc,label side up. • Most PCs include an optical disc drive Push the same buttonto close the tray. p. 366 Fig. 7-19

  25. Optical Discs disc label lens lens pit land Step 3.Reflected light is deflected to alight-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0. 0 1 prism prism light-sensingdiode light-sensingdiode laserdiode laserdiode Next • How does a laser read data on an optical disc? Step 2.If light strikesa pit, it scatters. If light strikes a land, it is reflected back toward diode. Step 1.Laser diode shines a light beam towarddisc. p. 367 Fig. 7-20

  26. Optical Discs Next • How is data stored on an optical disc? • Typically stored in singletrack • Track divided into evenly sizedsectorsthat store items single trackspirals to edgeof disc disc sectors p. 367 Fig. 7-21

  27. Optical Discs Next • How should you care for an optical disc? Do not exposethe disc to excessiveheat or sunlight Do store thedisc in a jewelbox whennot in use Do noteat, smoke, ordrink neara disc Do not stack discs Do hold a discby its edges Do not touchthe undersideof the disc p. 368 Fig. 7-22

  28. Optical Discs Next • What is aCD-ROM? • Compactdiscread-onlymemory • Cannot erase or modify contents • Typically holds 650 MB to 1 GB • Commonly used to distribute multimedia and complex software p. 369 Fig. 7-24

  29. Optical Discs Next • What is the data transfer rate of a CD-ROM drive? Ranges from 48X to 75X or faster 75X 75  150 KBps = 11,250 KBps or 12.25 MBps 75X is 150 KBps (KB per second) 48X: 48  150 KBps = 7,200 KBps or 7.2 MBps p. 369

  30. Optical Discs Stores digital versions of roll of film Film developers offer Picture CD service Can be modified using photo editing software Next • What is aPicture CD? Step 1.Drop off film to be developed. Mark the Picture CD box on the film-processing envelope. Step 3.At home, print images from Picture CD on your ink-jet photo printer. Step 2.When you pick up prints and negatives, a Picture CD contains digital images of each photograph. At a store, print images to Picture CD at kiosk. p. 370 Fig. 7-25

  31. Optical Discs Next • What areCD-Rs and CD-RWs? Must haveCD recorderor CD-R drive CD-R (compact disc-recordable) —cdisc you can write on once Cannot erasedisc’s contents CD-RW (compact disc-rewritable) —ceerasable disc you can write onmultiple times Must haveCD-RW softwareandCD-RW drive p. 371

  32. Optical Discs Next • What is aDVD-ROM(digital versatile disc-ROM or digital video disc-ROM)? • High capacity disc capable of storing 4.7 GB to 17 GB • Must haveDVD-ROM driveor DVD player to read DVD-ROM • Stores databases, music, complex software, and movies p. 372 Fig. 7-26

  33. Optical Discs Next • How does a DVD-ROM store data? • Two layers of pits are used, lower layer is semitransparent so laser can read through • Some are double-sided • Blu-Ray discs currently have a storage capacity of up to 27 GB p. 372 Fig. 7-27

  34. Tape Next • What istape? • Magnetically coated plastic ribboncapable of storing large amountsof data at low cost • Primarily used for backup p. 374 Fig. 7-28

  35. Tape Next • How is data stored on a tape? • Sequential access • Reads and writes data consecutively, like music tape • Unlike direct access — used on floppy disks, Zip disks, hard disks, CDs, and DVDs — which can locate particular item immediately p. 374

  36. PC Cards Next • What is aPC Card? • Adds capabilities to computer • Credit-card-sized device commonlyused in notebook computers p. 374 Figs. 7-29–7-30

  37. Miniature Mobile Storage Media Next • What isminiature mobile storage media? • Storage for small mobile devices p. 375 Fig. 7-31

  38. Miniature Mobile Storage Media CompactFlash Smart Media Secure Digital xD Picture Card Memory Stick Next • What are common types of flash memory cards? p. 376 Fig. 7-32

  39. Miniature Mobile Storage Media Next • How does one type of flash memory card work? p. 377 Fig. 7-33

  40. Miniature Mobile Storage Media Next • What is aUSB Flash Drive? • Plugs in a USB port on a computer or mobile device • Storage capacities up to 4 GB • May eventually make the floppy disk obsolete p. 377 Fig. 7-34

  41. Miniature Mobile Storage Media Next • What is asmart card? • Stores data on microprocessor embedded in small card • Input, process, output, and storage capabilities p. 378 Fig. 7-35

  42. Microfilm and Microfiche Microfilm — 100- to215-foot roll of film Microfiche — small sheet of film, usually 4”  6” Next • What aremicrofilmandmicrofiche? Store microscopic images of documents on roll or sheet of film Images recorded using computer output microfilm recorder p. 379 Fig. 7-36

  43. Microfilm and Microfiche Next • How do life expectancies of various media compare? • Microfilm and microfiche have longest life of any storage media p. 379 Fig. 7-37

  44. Putting It All Together Home Next • What are recommended storage devices for home users? • 80 GB hard disk • Online storage • CD or DVD drive • Card reader/writer • USB flash drive and/or 3.5-inch floppy disk drive p. 380 Fig. 7-38

  45. Putting It All Together Small Office/Home Office (SOHO) Next • What are recommended storage devices for small office/home office (SOHO) users? • 750 MB Zip drive • 120 GB hard disk • Online storage • CD or DVD drive • External hard drive for backup • USB flash drive and/or 3.5-inch floppy disk drive p. 380 Fig. 7-38

  46. Putting It All Together Mobile Next • What are recommended storage devices for mobile users? • 80 GB hard disk • Online storage • CD or DVD drive • Card reader/writer • Portable hard disk for backup • USB flash drive, and/or 2 GB PC Card hard disk, and/or 3.5-inch floppy disk drive p. 380 Fig. 7-38

  47. Putting It All Together Power Next • What are recommended storage devices for power users? • CD or DVD drive • 300 GB hard disk • Online storage • Portable hard disk for backup • USB flash drive and/or 3.5-inch floppy disk drive p. 380 Fig. 7-38

  48. Putting It All Together Large Business Next • What are recommended storage devices for large business users? • Desktop computer • 160 GB hard disk • CD or DVD drive • Smart card reader • Tape drive • USB flash drive and/or 3.5-inch floppy disk drive • Server or Mainframe • Network storage server • 40 TB hard disk system • CD-ROM or DVD-ROM server • Microfilm or microfiche p. 380 Fig. 7-38

  49. Summary of Storage Floppy disks Recordable DVDs Zip disks Rewritable DVDs Internal hard disks Tape Portable hard disks PC Cards Recordable CDs Flash memory cards and USB flash drives Rewritable CDs Smart cards, microfilm, and microfiche DVD-ROMs Chapter 7 Complete

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