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Storage Devices

Storage Devices. Chapter 4. Memory Cache. Speeds up computer by storing data the computer has recently used Internal Cache: On CPU chip (L1 or primary cache External Cache: On the system board and consists of Static RAM (SRAM chips) Sometimes built into chip RAM – slower main memory

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Storage Devices

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  1. Storage Devices Chapter 4

  2. Memory Cache • Speeds up computer by storing data the computer has recently used • Internal Cache: On CPU chip (L1 or primary cache • External Cache: On the system board and consists of Static RAM (SRAM chips) • Sometimes built into chip • RAM – slower main memory • Each time the computer requests data from RAM, the computer places a copy of the data in memory cache • Constantly contains the most recently used data

  3. BUS • Electronic pathway that carries information between devices in a computer • Bus Width (think lanes of a highway) • 8 bits is one character • Bus Speed (think speed limit) • Measured in MHz (millions of cycles per second)

  4. Bus Types • ISA (Industry Standard Architecture) • Slowest and oldest • 16 bits; 8MHz (millions of cycles per second) • Pentium, Pentium II • PCI (Peripheral Component Interconnect) • 32 or 64 bits • 66 MHz • Support Plug and Play • Pentium II, III, 4 • AGP (Accelerated Graphics Port) • Between video card and main memory • 32 bits; 66 MHz

  5. Using a Hard Drive Correctly • Virus protection • Backups • Defragmentation • Prevents files from being broken up for storage • Repairing a Disk • Disk Cleanup • Data compression • Only if disk is running out of space

  6. Hard Drives • Magnetically stores data on rotating disks called platters • Stores your operating system and programs • Document will not be lost when you turn off the computer • Capacity is measured in bytes • Speed is measured in revolutions per minute

  7. File Systems • File system determines how information is stored on a hard drive • FAT • FAT32 • NTFS

  8. Connection Types • EIDE (Enhanced Integrated Drive Electronics) – Called IDE • Supports total of 4 devices (any drives) • Ultra Direct Memory Access (UDMA) is enhanced IDE • SCSI (Small Computer System Interface) • Called ‘scuzzy” • Supports 7 devices • Expensive

  9. Relation of Cache & Hard Drives • Disk cache speeds up the computer by storing the data the computer has most recently used • Constantly updated • Area of memory • Fast access • Then hard drive is searched

  10. Floppy Drives and Drives • Removable media • Can be write-protected • Can be damaged magnetically

  11. CD-ROM • ROM (Read-only memory) - can’t be changed • 650 Mb of data • Equal to entire set of encyclopedias • 400 Floppy disks • Music, games, software installs • Speed determines how fast a disk spins • Look for 24X • Speed of CD-ROM drive is the transfer rate • In Kb (e.g. 3600Kbs)

  12. CD-R & CD-RW Drives • CD-R (Compact Disc – Recordable) • Permanent store; not erasable • CD-RW • Can be erased and rewritten • Read / Write and Re-write speeds • Usually 74 minutes • Special software needed to record onto a disk • Referred to as burning a CD

  13. DVD-ROM Drive • DVD – Digital Versatile Disk • Generally cannot change the information stored on a disk • Similar to CD but stores more information • Speed determines transfer rate (6 X) • Capacity • 1 side / 1 layer – 4.7 GB • 1 side / 2 layer – 8.5 GB • 2 sides / 1 layer – 9.4 GB • 2 sides / 2 layers – 17 GB

  14. Tape Drive • Backup helps you copy files to tape cartridges • Tape drives come with backup programs • Schedule backups to run at night • Backup programs compress data together • Try to find a drive that can store the entire contents of your hard drive • Travan drives are the most common type of tape drives – 10 GB • DAT drives are faster than a Travan – 24GB

  15. Tape Backups • Full • Incremental

  16. Removable Storage Devices • Jazz Drive – 2 GB • Zip Drive – 250 MB • LS-120 Drive – 120 MB

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