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Discovering Computers 2011

Discovering Computers 2011. Chapter 6 Computer Storage Issues . Chapter Objectives. Next. Differentiate among CD-ROMs, recordable CDs, rewritable CDs, DVD-ROMs, BD-ROMs, HD DVD-ROMs, recordable DVDs, and rewritable DVDs. Differentiate between storage devices and storage media.

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Discovering Computers 2011

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  1. Discovering Computers 2011 Chapter 6 Computer Storage Issues

  2. Chapter Objectives Next Differentiate among CD-ROMs,recordable CDs, rewritable CDs, DVD-ROMs, BD-ROMs, HD DVD-ROMs, recordable DVDs, and rewritable DVDs Differentiate between storage devicesand storage media Describe the characteristics ofmagnetic disks Identify the uses of tape Describe the characteristics of a hard disk Discuss PC Cards, ExpressCard modules, and the various types of miniature storage media Discuss various types of miniature, external, and removable hard disks Describe the characteristics of optical discs Identify uses of microfilm and microfiche

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

  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 210 220 230 240 250 260 270 280 290 ???

  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

  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

  7. Storage Transfer rates 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

  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 Usually done before purchase But can be done by user

  9. Magnetic Disks Perpendicular recording Longitudinal recording Next hard disk mountedin system unit • What is ahard disk? • High-capacity storage • Consists of several inflexible, circular platters that store items electronically • Components enclosed in airtight, sealed case for protection Newest, More capacity

  10. Magnetic Disks Sample Hard Disk Characteristics Advertised capacity 500 GB Platters 4 Read/write heads 8 Cylinders 16,383 Bytes per second 512 Sectors per track 63 Sectors per drive 973,773,168 Revolutions per minute 7,200 Transfer rate 300 MB per second Access time 8.5 ms Next • What are characteristics of a hard disk? actualdiskcapacity

  11. 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.

  12. 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 cylinder

  13. 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

  14. Magnetic Disks first requestfor data—to disk cache second requestfor data—to hard disk Next • What is adisk cache? • Portion of memory that processor uses to store frequently accessed items

  15. 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 SCSIcontroller supports up to fifteendevices including hard disks, CDand DVD drives, tape drives, printers,scanners, network cards Next • What is adisk controller?

  16. Magnetic Disks Next • What is afloppy disk? • Portable, inexpensive storage medium (also called diskette) Thin, circular, flexible film enclosedin 3.5” wide plastic shell

  17. Magnetic Disks Next • What is a miniature hard disk? • Provide greater storage capacities than flash memory • Smaller than notebook computer hard disks • A pocket hard drive is a self-contained unit

  18. Magnetic Disks Next • What areexternal hard disksandremovable hard disks? • Used to back up or transfer files External hard disk—freestanding hard disk that connects to system unit Removable hard disk— hard disk that you insert and remove from hard disk drive

  19. Magnetic Disks Next • What is RAID? • A big storage box • Redundant Array of Independent Disks Redundant Array of Inexpensive Drives, Devices • Connects multiple smaller disks into a single unit that acts as a single large hard disk

  20. 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 • The Cloud – Perhaps the ultimate storage?!

  21. 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.

  22. 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.

  23. 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

  24. Optical Discs Next • How should you care for an optical disc?

  25. Optical Discs Next • What is aCD-ROM? • CompactDiscRead-OnlyMemory • Cannot erase or modify contents • Typically holds 650 MB to 1 GB [680-720 MB most common] • Commonly used to distribute multimedia and complex software

  26. 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 1X was the original transfer rate, 150 KBps

  27. Optical Discs Stores digital versions of roll of film (Remember?) 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.

  28. 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 WORM! Cannot erasedisc’s contents CD-RW (Compact Disc-ReWritable) —ceerasable disc that you can write on multiple times Must haveCD-RW softwareandCD-RW drive W – Write O – Once R – Read M – Many

  29. Optical Discs Next • What is aDVD-ROM(digital versatile disc-ROM or digital video disc-ROM)? • Must haveDVD-ROM driveor DVD player to read DVD-ROM • Stores databases, music, complex software, and movies • Blu-ray discs (BD) have storage capacity of up to 100 GB (Sony) • HD-DVD discs have storage capacity of up to 60 GB (Hitachi, defunct) • Universal Media Disc (UMD) for PlayStation portable, can store up to 1.8 GB

  30. 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 • Many types of recordable and rewritable DVDs are available • DVD-R and DVD+R • DVD-RW and DVD+RW

  31. Tape Next • What istape? • Magnetically coated plastic ribboncapable of storing large amountsof data at low cost • Primarily used for backup • Dead medium, keeps coming back ;-)

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

  33. PC Cards and ExpressCard Modules Next • What arePC Cards and ExpressCard Modules? • Add capabilities to computer • Credit-card-sized device commonly used in notebook computers

  34. Miniature Mobile Storage Media Next • What isminiature mobile storage media? • Storage for small mobile devices

  35. Miniature Mobile Storage Media CompactFlash (CF) Secure Digital (SD) xD Picture Card Memory Stick PRO Duo Memory Stick Next • What are common types of flash memory cards?

  36. 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 64 GB • May eventually make the magnetic disk obsolete

  37. Miniature Mobile Storage Media Next • What is asmart card? • Stores data on microprocessor embedded in small card • Input, process, output, and storage capabilities

  38. 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

  39. Microfilm and Microfiche Next • How do life expectancies of various media compare? • Microfilm and microfiche have longest life of any storage media

  40. Putting It All Together Next • What are recommended storage devices for home users? • 250+ GB hard disk • Online storage • CD or DVD drive • Card reader/writer • USB flash drive

  41. Putting It All Together Next • What are recommended storage devices for small office/home office (SOHO) users? • 500+ GB hard disk • Online storage • CD or DVD drive • External hard drive for backup • USB flash drive

  42. Putting It All Together Next • What are recommended storage devices for mobile users? • 100+ GB hard disk • Online storage • CD or DVD drive • Card reader/writer • Portable hard disk for backup • USB flash drive

  43. Putting It All Together Next • What are recommended storage devices for power users? • 1.5 TB hard disk • Online storage • CD or DVD drive • Portable hard disk for backup • USB flash drive

  44. Putting It All Together Next • What are recommended storage devices for large business users? • Desktop computer • 500+ GB hard disk • CD or DVD drive • Smart card reader • Tape drive • USB flash drive • Server or Mainframe • Network storage server • 40 TB hard disk system • CD-ROM or DVD-ROM server • Microfilm or microfiche

  45. Summary of Storage Internal hard disks HD DVD discs External and removable hard disks Recordable and Rewritable DVDs Floppy disks Tape CD-ROMs PC Cards and ExpressCard modules Recordable and Rewritable CDs Flash memory cards and USB flash drives DVD-ROMs Smart cards, microfilm, and microfiche Blu-ray Discs (BDs) Chapter Complete

  46. Miniature Mobile Storage Media Next • How does one type of flash memory card work?

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