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Magnetic Storage Concepts

Magnetic Storage Concepts. How Computers Use Magnets. Lesson Objectives. Introduce magnetism as a memory tool Motivate the need for efficient “permanent” memory Demonstrate the ability to magnetize Demonstrate the use of magnetism to store information

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Magnetic Storage Concepts

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  1. Magnetic Storage Concepts How Computers Use Magnets

  2. Lesson Objectives • Introduce magnetism as a memory tool • Motivate the need for efficient “permanent” memory • Demonstrate the ability to magnetize • Demonstrate the use of magnetism to store information • Reinforce the idea that computers “speak” binary, requiring us to encode and decode • Introduce the topic of electro-magnetism

  3. Memory Types • Short-term memory is used for things that you probably will need to use soon • Humans use their index cards, mnemonics, etc. • Computers use RAM and caches • Long-term memory is for things may not need for a long time but don’t want to forget • Humans use notebooks, reference books, libraries, audio tape, video tape, etc. • Computers use floppy disks, hard disks, CDs, etc.

  4. Disk Anatomy • Floppy disks contain a circular piece of plastic embedded with millions of elements of magnetic material • Hard disks are similar but consist of hard platters holding the magnetic elements • Both types of disks are divided into tracks which are further divided into sectors • Both have read/write “heads” on “arms” that are positioned based on addresses

  5. Why Use Magnets? • Magnetic material is readily available and therefore relatively cheap • It can also be formed into many shapes • We can work with very small magnets • Magnets hold state extremely well • In summary, magnets: • Don’t take up much space • Don’t cost much • Are reliable • And can be written to and read from quickly

  6. Making Magnets • A ferromagnetic material (such as iron or steel) can be magnetized by exposing it to a magnetic field • If its magnetic domains align and “stick”, it becomes a “permanent” magnet • It now has north and south poles • It also emits a magnetic field which can be “read”

  7. Exercise • Encode your group’s letter using the attached chart • Magnetize “bits” by rubbing them with your permanent magnet 20 – 40 times • Test each “bit” by trying to pick up a paper clip • Read and decode your neighbor’s letter • Write their letter on the board

  8. Exercise Objectives • Learn how to magnetize an object and use that property to hold state information • Encode to store information in binary and decode to read it back • Appreciate the importance of maintaining place order

  9. Improvement Opportunities • RAM vs. disk • Optical storage

  10. Lesson Summary • Computers use magnetism for fairly fast, pretty cheap, long-term storage • Magnetic material can be magnetized by exposing it to a strong magnetic field • Floppy and Hard Disks consist of millions of tiny elements that can be magnetized • Computers store data “permanently” by magnetizing and demagnetizing these elements

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