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Tuesday, December 14

  1. page Magnetic Storage Devices edited Magnetic Storage Devices Information Magnetic storage uses different patterns of magnetiza…

    Magnetic Storage Devices
    Information Magnetic storage uses different patterns of magnetization on a magnetically coated surface to store information. Magnetic storage is non-volatile. The information is accessed using one or more read/write heads which may contain one or more recording transducers. A read/write head only covers a part of the surface so that the head or medium or both must be moved relative to another in order to access data. In modern computers, magnetic storage will take these forms:
    Magnetic disk
    Floppy disk, used for off-line storage
    Hard disk drive, used for secondary storage
    Magnetic tape data storage, used for tertiary and off-line storage
    In early computers, magnetic storage was also used for primary storage in a form of magnetic drum, or core memory, core rope memory, thin-film memory, twistor memory or bubble memory. Also unlike today, magnetic tape was often used for secondary storage.
    What Is a Magnetic Storage Device?
    One of the common aspects of modern computer hardware is a technology known as a magnetic storage device. This is a technology available in multiple forms, such as a floppy disk drive, a tape drive and a hard drive.
    Magnetic Storage Basics A magnetic storage device works on a principal of magnetic charge. The basic premise is that a magnetizable medium, such as a metal wire, can be magnetized by an electric magnet. It can then be "read" magnetically and its recorded "data" played back.
    Audio Recording Magnetic storage was first used for audio recording, and is generally referred to as magnetic recording. The basic principle is the same. Modern audio recording often uses a digital magnetic storage device.
    Digital Recording A digital magnetic storage device records (stores data) in a stepped pattern. This is because a digital signal consisting of only two main states. A digital stream of data is as a binary signal containing a sequence of 1's and 0's, so only two magnetic states are necessary.
    Magnetic Storage Devices A magnetic storage device is a device that uses a magnetic head to read and write data to and from a magnetizable medium. The medium can be as basic as a plastic tape that is coated with fine particles of a metal, such as is found in audio recording and tape storage devices.
    Types of Magnetic Storage Devices There are many types of magnetic storage devices. Audio tape is an early example of magnetic recording that later transitioned into use for computer data storage. A computer's hard disk is a more modern example of magnetic data storage. A floppy disk is yet another example.
    Sample Exam Question A PC incorporates a hard disk, a CD-R drive and a DVD-RW drive. Describe three ways in which the hard disk will be used.[6]
    1._
    _
    _
    2._
    _
    _
    3._
    _
    __
    Answer
    To store user data
    . . . ‘permanently’/when the computer is switched off/for future access
    [1] for each of two points
    To store application software
    . . . from where it will be loaded into RAM to be executed/where SW is
    installed
    [1] for each of two points
    To store the ‘non-core’ of the operating system
    . . . from where it will be loaded into RAM to be executed
    [1] for each of two points
    [2] for each of three ways [6]

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    2:01 am

Monday, December 13

  1. page space.menu edited [[include component="pageList" hideInternal="true" limit="10" ]] Sen…
    [[include component="pageList" hideInternal="true" limit="10" ]]
    Sensors and Data logging
    Storage Devices- CD
    Sample Questions
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    12:48 pm

Thursday, December 9

  1. page Storage Devices- CD edited ... It is usually 120 mm in diameter and holds 700 MB of space It expanded into different types o…
    ...
    It is usually 120 mm in diameter and holds 700 MB of space
    It expanded into different types of discs like CD-ROM, CD-R, CD-RW, VCD, CD-i etc.
    Data is literally burnt onto the CD using a laser hence it is called burning a CD when writing data onto a CD
    The data is read by the laser being reflected off the burnt space going into a sensor

    Advantages
    Can hold lots of media
    ...
    Disadvantages
    Easily damaged
    If theMany types of CD are easily copied causing lot of copytright issues
    CD-ROM
    A pre-burnt CD that can be written only once and then used for Reading only
    ...
    Can only be read on a computer and on a CD player but with audio only
    Can hold up to 900 MB
    Advantages
    It is easily transportable and is compatible with any other PC or laptop
    Can store more data than a usual CD
    Disadvantages
    Expensive
    Easily damaged
    Information is fixed therefore hard to update
    CD-R
    A CD that is recordable but only once, similar to CD-ROM but it is recordable by the user
    It is an example of Write Once, Read Many (WORM) storage
    Mostly used as a one session backup as it is WORM type storage
    Advantages
    Cheap
    Hugely accessible for everyday use
    Disadvantage
    With WORM storage the data burnt onto it cannot be changed once written with no way of updating the data.
    Short lifespan
    CD-RW
    This type of CD is re-writable
    It's structure is different from other CD's making it re-writable
    It is mostly used for backing up files or when transporting files across PC's
    Advantages
    Re-writable disc allows the user to update or correct the data recorded on the disc
    Highly accessible and cheap
    Disadvantages
    Short lifespan
    Slower to write
    Not compatible with older CD players and drives (11-12 years old or more)

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    1:41 pm

Wednesday, December 8

  1. page Storage Devices- CD edited CD Compact Disc abbrieviated CD is a famous storage device used since 1982 It peaked as the mo…

    CD
    Compact Disc abbrieviated CD is a famous storage device used since 1982
    It peaked as the most used portable storage device until 2000
    It is usually 120 mm in diameter and holds 700 MB of space
    It expanded into different types of discs like CD-ROM, CD-R, CD-RW, VCD, CD-i etc.
    Advantages
    Can hold lots of media
    Easy to carry
    Cheap
    Disadvantages
    Easily damaged
    If the CD
    CD-ROM
    A pre-burnt CD that can be written only once and then used for Reading only
    Most popular in distributing computer software, video games etc
    Can only be read on a computer and on a CD player but with audio only
    Can hold up to 900 MB

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    1:59 pm

Monday, December 6

  1. page Input Devices-OCR OMR MICR and Barcode edited ... Document Readers OCR Optical Character Recognition abbrieviated OCR

    ...
    Document Readers
    OCR
    Optical Character Recognition abbrieviated OCR
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    4:26 am
  2. page Input Devices-OCR OMR MICR and Barcode edited ... Document Readers OCR Optical Character Recognition abbrieviated OCR

    ...
    Document Readers
    OCR
    Optical Character Recognition abbrieviated OCR
    (view changes)
    1:53 am

Thursday, December 2

  1. page Storage Device - Floppy & Zip Disks edited Storage Devices Floppy Disks Typical Uses Advantages & Disadvantages Zip Disks Typical…

    Storage Devices
    Floppy Disks
    Typical Uses
    Advantages & Disadvantages
    Zip Disks
    Typical Uses
    Advantages & Disadvantages

    (view changes)
    2:20 am

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