1 / 48

C OMPUTING

C OMPUTING. E SSENTIALS. 1999. 2000. 1999. 2000. Timothy J. O’Leary Linda I. O’Leary. 1999. Presentations by: Fred Bounds. 2000. Secondary Storage. 5. CHAPTER. Competencies. After reading this chapter, you should be able to:

field
Download Presentation

C OMPUTING

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. COMPUTING ESSENTIALS 1999 2000 1999 2000 Timothy J. O’Leary Linda I. O’Leary 1999 Presentations by:Fred Bounds 2000

  2. Secondary Storage 5 CHAPTER

  3. Competencies After reading this chapter, you should be able to: 1. Describe today’s standard floppy disk and compare it to Zip, SuperDisks and HiFD disks. 2. Describe the following kinds of disks: internal hard disks, hard-disk cartridges and hard-disk packs. Computing Essentials 1999 - 2000 Chapter Five

  4. Competencies 3. Describe ways to improve hard-disk operations: disk caching, redundant arrays of inexpensive disks and data compression. 4. Compare the CD and DVD optical disk formats. Computing Essentials 1999 - 2000 Chapter Five

  5. Competencies 5. Describe the different types of optical disks. 6. Describe magnetic tape streamers and magnetic tape reels. Computing Essentials 1999 - 2000 Chapter Five

  6. Overview • Computers permanently save information • For future use • To share information with others • To modify information already available • Stores programs and data • As opposed to temporary storage (RAM), which is volatile, secondary storage is nonvolatile Computing Essentials 1999 - 2000 Chapter Five

  7. Floppy Disks Floppy disks are removable storage media. Today’s standard is 1.44 MB. Tomorrow’s might be a Zip, SuperDisk or HiFD. Data is recorded on tracks and sectors.

  8. Floppy Disks • Removable storage media inserted into disk drives • Flat circular pieces of mylar plastic rotating within a jacket • The bits of data are represented by the presence or absence of magnetic charges Computing Essentials 1999 - 2000 Chapter Five

  9. Floppy Disks - Today’s Standard • Storage capacities range from 360 KB to 1.44 MB • Jackets covering the mylar disk can be flexible or sturdy • Write-protect notch or window to prevent inadvertent erasure or write-over Computing Essentials 1999 - 2000 Chapter Five

  10. Floppy Disks - Tomorrow’s Standard • Zip Disks • 100 MB capacity (70 times regular floppy) • Becoming standard feature on new systems • May be the next floppy disk standard • SuperDisks • 120 MB capacity • Can read and write standard floppies, while Zips cannot Computing Essentials 1999 - 2000 Chapter Five

  11. Floppy Disks - Tomorrow’s Standard • HiFD disks • 200 MB capacity (140 times standard floppy) • Can also read and write standard floppies Computing Essentials 1999 - 2000 Chapter Five

  12. The Parts of a Floppy Disk • Data recorded in rings called called tracks • Tracks divided into wedge-shaped sections called sectors • Most disks manufactured without tracks and sectors and must have “soft sectors” added through the formatting process Computing Essentials 1999 - 2000 Chapter Five

  13. Typical Floppy Disk Capacities 2HD 1.44 MB SuperDisk 120 MB Computing Essentials 1999 - 2000 Chapter Five

  14. access arm read-write head tracks (invisible) 3 1/2-inch floppy disk How a Disk Drive Works • Drive motor turns mylar disk • Access arm moves read-write heads back and forth • Read-write heads then read or write on the disk surface Computing Essentials 1999 - 2000 Chapter Five

  15. Hard Disks Hard disks are of three types: internal hard disk, hard-disk cartridge and hard-disk pack.

  16. Hard Disks • Composed of metallic rather than plastic disks • Fast information storage and retrieval • Read-write heads “fly” over the disk surface on a cushion of extremely thin air Computing Essentials 1999 - 2000 Chapter Five

  17. Hard Disks • A smoke particle, human hair or fingerprint could cause a head crash • Head crashes occur when the read-write head contacts the disk surface Computing Essentials 1999 - 2000 Chapter Five

  18. Materials that can cause a head crash Computing Essentials 1999 - 2000 Chapter Five

  19. Materials that can cause a head crash dust particle fingerprint smoke particle human hair Computing Essentials 1999 - 2000 Chapter Five

  20. Internal Hard Disk • Located inside the system unit • Also known as fixed disk • For storing the operating system, other programs and large data files Computing Essentials 1999 - 2000 Chapter Five

  21. Internal Hard Disk • One or more metallic platters sealed inside a container • Container holds • Motor for rotating the disks • Access arm and read-write heads Computing Essentials 1999 - 2000 Chapter Five

  22. Internal Hard Disk • Advantages over floppy disks • Capacity (up to thousands times a single floppy • Speed (ten times the speed) Computing Essentials 1999 - 2000 Chapter Five

  23. Hard-Disk Cartridges • Hard disk can be easily removed • Give microcomputer fast access to large amounts of data Computing Essentials 1999 - 2000 Chapter Five

  24. Hard-Disk Cartridges • Complements internal hard disk • Typical capacity, 2 GB • Popular vendors: Iomega and SyQuest Computing Essentials 1999 - 2000 Chapter Five

  25. Hard-Disk Packs • Removable, massive storage capacity • Common in mainframe systems • Composed of a larger number of platters, resembling a stack of record albums Computing Essentials 1999 - 2000 Chapter Five

  26. Hard-Disk Packs • Most platters offer read-write surfaces on top and bottom • Used with larger computer systems Computing Essentials 1999 - 2000 Chapter Five

  27. Hard-Disk Packs • Access time - time between the computer’s request for data from secondary storage and the completion of the data transfer Computing Essentials 1999 - 2000 Chapter Five

  28. Performance Enhancements • Disk caching • Uses hardware and software to anticipate data needs • Frequently used data is stored in memory, when needed, the access time is much faster Computing Essentials 1999 - 2000 Chapter Five

  29. Performance Enhancements • Redundant arrays of inexpensive disks (RAID) • Groups of low cost hard-disk drives grouped together using networks and special software • Performs as a single large-capacity disk • But faster than a single disk of comparable size Computing Essentials 1999 - 2000 Chapter Five

  30. Performance Enhancements • File compression and decompression • Increase storage capacity • Reduce space required for storage • Aids in file transmission • WinZip and PKZip are well-known programs Computing Essentials 1999 - 2000 Chapter Five

  31. Optical Disks Optical disks use laser technology. CD and DVD are optical disk formats.

  32. Optical Disks • Compact, high capacity form of permanent storage • Laser beam writes by creating a pattern of pits (holes) and lands (flat areas) to encode data bits • Laser beams reflect off the pits and lands to read the data Computing Essentials 1999 - 2000 Chapter Five

  33. Optical Disks • Up to 4.7 gigabytes of data • Equivalent of over 1 million typewritten pages • Three types of optical discs CD-ROM, CD-R and erasable optical discs, or CD-RW Computing Essentials 1999 - 2000 Chapter Five

  34. CD-ROM • Stands for compact disc-read-only memory • Can be read from, but not written to • Can hold up to 650 MB of information • Grolier Electronic Encyclopedia - nine million words and 1900 pictures • Used to distribute large software packages Computing Essentials 1999 - 2000 Chapter Five

  35. Reflected light Reflecting surface Laser beam CD-ROM drive CD-ROM How a CD-ROM works CD-ROM carrying case Computing Essentials 1999 - 2000 Chapter Five

  36. CD-R • Stands for CD-Recordable • Also known as WORM, or write once, read many • Ideal for use as permanent data archives for essential company information • CD changers or CD jukeboxes can facilitate rapid access to large amounts of information Computing Essentials 1999 - 2000 Chapter Five

  37. CD-RW • Also known as rewritable optical discs • Unlike CD-R, these discs can be written on numerous times • Most common technology is magneto-optical (MO) disc drive, combining magnetic and optical technologies • Capacities up to 1,000 megabytes (a gigabyte) Computing Essentials 1999 - 2000 Chapter Five

  38. Digital Versatile Disk • Commonly known as digital video disk or DVD • Up to 4.7 gigabytes capacity, seven times CD • With two-sided storage, 17 gigabytes out soon • Predicted to replace CD as a standard Computing Essentials 1999 - 2000 Chapter Five

  39. Digital Versatile Disk • DVD-ROM - provide high quality, movie length videos • DVD-R - consumer recordable version just getting started • DVD-RAM or DVD-RW - rewritable version Computing Essentials 1999 - 2000 Chapter Five

  40. Magnetic Tape Magnetic tape streamers and magnetic tape reels are used primarily for backup purposes.

  41. Magnetic Tape • Disks offer fast, direct access to data programs • Tapes are sequential access, because they have to be fast forwarded or rewound before a specific location can be reached Computing Essentials 1999 - 2000 Chapter Five

  42. Magnetic Tape • A common sequential access method of permanent storage method • A common form of data backup in companies with larger computer systems Computing Essentials 1999 - 2000 Chapter Five

  43. Magnetic Tape • Two forms of tape storage • Magnetic tape streamers • Magnetic tape reels Computing Essentials 1999 - 2000 Chapter Five

  44. Backup tape cartridge units used with microcomputer systems Typical capacities range from 120 MB to 5 GB Advanced forms use digital audio tape (DAT) Magnetic Tape Streamers Computing Essentials 1999 - 2000 Chapter Five

  45. Magnetic Tape Reels • Used with minicomputer and mainframe computers • Often 1/2 inch wide and 1/2 mile long • Stores 1600 to 6400 characters per inch • Tapes are run on magnetic tape drives or magnetic tape units Computing Essentials 1999 - 2000 Chapter Five

  46. Magnetic Tape Reels • Used with minicomputer and mainframe computers • Often 1/2 inch wide and 1/2 mile long • Stores 1600 to 6400 characters per inch • Tapes are run on magnetic tape drives or magnetic tape units Computing Essentials 1999 - 2000 Chapter Five

  47. Read-write head Erase head Magnetic Tape Reels Take-up reel Supply reel Tape Computing Essentials 1999 - 2000 Chapter Five

  48. Computing Essentials 1999 - 2000 Chapter Five

More Related