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CIS 141 Lecture Storage Hardware (saving data/information)

CIS 141 Lecture Storage Hardware (saving data/information). Thad Crews Western Kentucky University. SAVING INFORMATION Storage Hardware. Digital systems have discrete values 1 / 2 / 3 / 4 / 5 On / Off Digital with two states is called Binary Analog systems have continuous data values.

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CIS 141 Lecture Storage Hardware (saving data/information)

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  1. CIS 141 LectureStorage Hardware (saving data/information) Thad Crews Western Kentucky University

  2. SAVING INFORMATIONStorage Hardware

  3. Digital systems have discrete values 1 / 2 / 3 / 4 / 5 On / Off Digital with two states is called Binary Analog systems have continuous data values (Remember: Digital vs. Analog)

  4. A bit (e.g., “binary digit”) is a single one (1) or zero (0). Eight bits is a byte – the standard grouping in digital electronics 1’s and 0’s can be used to represent: Numbers Letters Sounds Images Videos (Remember: Bits and Bytes)

  5. Input – Process – Output

  6. Storage This memory is volatilewhich means it requires electrical power to hold its value.

  7. Storage STORAGE • Hard Disk (magnetic) • CD/DVD/BD (optical) • USB Flash (solid state) “RAM” “Memory” “Main Memory” “Secondary Memory” “Storage”

  8. Main Memory vs. Storage • Memory is volatile — holds data and instructions temporarily • Storage is nonvolatile— contents retained when power is off

  9. So why not use “Storage” hardware for “Main Memory”?

  10. Memory/Storage Hierarchy

  11. Solid State Storage (Storage 1 of 3) Mini Memory Card • Flash memory resides on a chip (e.g., solid state; no moving parts; like RAM.) However, flash memory is nonvolatile so it retains its information when it is “unplugged.” A single 8GB USB/thumb/flash drive stores as much data as 1,000+ CDs

  12. Magnetic Storage (Storage 2 of 3) • A hard disk is the most common magnetic storage media, consisting of several inflexible platters covered with magnetic material enclosed in an airtight, sealed case. • Hard drive platters spin at a rate of ~8000 RPM.

  13. The read/write head

  14. Hard Disk • A head crash occurs when the read/write head touches the platter surface. • Clearance between head and platter is approximately two-millionths of an inch Do NOT shake your machine while your hard drive is spinning.

  15. Hard Disks • A Redundant Array of Independent Disks (RAID) connects multiple disks into a single unit to achieve high levels of storage reliability.

  16. Older magnetic storage media • Floppy disks • Tape drives

  17. Your next computer may have a solid state drive (SSD) instead of a hard drive. SSD Advantages: Faster (no spin start up, no moving head seek) Silent operation due to lack of moving parts Low power consumption Generate little heat Low failure rate SSD Disadvantages More expensive per gigabyte Great difference between write speed and read speed (may cause problems) Solid State Drive vs. Hard Disk Drive

  18. SSD (Solid State Disks) Many competing standards

  19. CD, DVD, Blu-laser Disc (BD) are all optical media that use a laser to read and write the data on the disc. Optical Media Storage (Storage 3 of 3) Note: Magnetic disks are spelled with a “K”, and optical discs are spelled with a “C”.

  20. 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. 1 0 prism prism light-sensingdiode light-sensingdiode laserdiode laserdiode 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.

  21. CD, DVD, Blu-laser Disc (BD) Optical Discs 1 CD = 486 Floppy Disks 1 DVD = 3,263 Floppy Disks 1 BD = 17,361 Floppy Disks

  22. Recent News Stories about Storage • NSA Spy Center: • Read more here • White House Shares $200 Million Big Data Plan: • Read more here • 60th Anniversary of Tape Storage: • Read more here

  23. SUMMARY (Computer Hardware) Ch6 Ch7 Ch7 Ch8 Quiz1

  24. (Remember: Prefixes) • A byte is about the size it takes to store a letter of the alphabet. • A kilobyte is about the storage you would need for a six-page paper. • 1.44 megabytes: A floppy disk. • 500 megabytes: CD-ROM • 4.7 gigabytes: DVD Disc • 25 gigabytes: Blu-Ray Disc • 1 terabyte: All the X-ray films in a large technological hospital • 10 terabytes: Printed collection of the U. S. Library of Congress • 500 terabytes: All the information in all the books ever written • 24 petabytes: Google’s daily processing • 500 exabytes: The world’s total digital content (as of May 2009).

  25. Big Picture (Computer Hardware)

  26. Big Picture (Computer Hardware)

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