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    What Is A Magnetic Disk?

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    Thanh Long Pham
    Magnetic disks are flat circular platters coated with magnetic material that are used for secondary storage. Data is stored in small sections called sectors that are arranged in concentric circles called tracks. A read/write head accesses the data by moving along the tracks on the disk. Magnetic disks can store large amounts of data more cheaply than RAM but are slower to access. The first magnetic hard drive from 1956 could only store 5 megabytes despite its large size, but storage capacity has increased dramatically while sizes have decreased since then.

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    What Is A Magnetic Disk?

    Uploaded by

    Thanh Long Pham
    61 views3 pages
    Magnetic disks are flat circular platters coated with magnetic material that are used for secondary storage. Data is stored in small sections called sectors that are arranged in concentric circles called tracks. A read/write head accesses the data by moving along the tracks on the disk. Magnetic disks can store large amounts of data more cheaply than RAM but are slower to access. The first magnetic hard drive from 1956 could only store 5 megabytes despite its large size, but storage capacity has increased dramatically while sizes have decreased since then.

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    Magnetic disks are flat circular platters coated with magnetic material that are used for secondary storage. Data is stored in small sections called sectors that are arranged in concentric circles called tracks. A read/write head accesses the data by moving along the tracks on the disk. Magnetic disks can store large amounts of data more cheaply than RAM but are slower to access. The first magnetic hard drive from 1956 could only store 5 megabytes despite its large size, but storage capacity has increased dramatically while sizes have decreased since then.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    61 views3 pages

    What Is A Magnetic Disk?

    Uploaded by

    Thanh Long Pham
    Magnetic disks are flat circular platters coated with magnetic material that are used for secondary storage. Data is stored in small sections called sectors that are arranged in concentric circles called tracks. A read/write head accesses the data by moving along the tracks on the disk. Magnetic disks can store large amounts of data more cheaply than RAM but are slower to access. The first magnetic hard drive from 1956 could only store 5 megabytes despite its large size, but storage capacity has increased dramatically while sizes have decreased since then.

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    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
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    What Is A Magnetic Disk?

    A Magnetic Disk is a type of secondary memory that consists of a flat disc with a
    magnetic coating that stores data. It's where you keep all of your apps and files.
    One represents polarised information in one direction and vice versa. The
    direction is denoted by the number 0.

    Magnetic discs are less expensive than RAM and can store vast amounts of data;
    however, secondary memory slows data access compared to main memory. In the
    magnetic disc memory, data can be easily edited or removed. It also provides for
    data access at any time.

    IBM produced the first magnetic hard drive in 1956, a big system with 50 21-inch
    (53-cm) discs. Unfortunately, it could only store 5 megabytes of data despite its
    size. Since then, magnetic discs have expanded their storage capacity by orders of
    magnitude while shrinking.

    The working of magnetic disk


    » The surface of disk is divided into concentric circles known as tracks. The
    outermost track is numbered 0 and the innermost track is the last track. Tracks
    are further divided into sectors. A sector is a pie slice that cuts across all tracks.
    The data on disk is stored in sector. Sector is the smallest unit that can be read or
    written on a disk. A disk has eight or more sectors per track
    » Magnetic disk is inserted into a magnetic disk drive for access. The drive
    consists of a read/write head that is attached to a disk arm, which moves the
    head. The disk arm can move inward and outward on the disk.
    » During reading or writing to disk, the motor of disk drive moves the disk at
    high speed (60–150 times/sec.)

    Accessing data on the disk requires the following —


    Seek Time
    The read/write head is positioned to the desired track where the data is to be
    read from or written to. The time taken to move the read/write head to the
    desired track is called the seek time.

    Latency Time
    Once the read/write head is at the right track, then the head waits for right sector
    to come under it (disk is moving at high speed). The time taken for desired
    sector of the track to come under read/write head is called the latency time.

    Data Transfer Rate


    Once the read/write head is positioned at the right track and sector, the data has
    to be written to disk or read from disk. The rate at which data is written to disk
    or read from disk is called data transfer rate.

    Access Time
    The sum of seek time, latency time and time for data transfer is the access time
    of the disk.

    » The storage capacity of disk drive is measured in gigabytes (GB).


    » Large disk storage is created by stacking together multiple disks. A set of
    same tracks on all disks forms a cylinder. Each disk has its own read/write head
    which work in coordination.
    » A disk can also have tracks and sectors on both sides. Such a disk is called
    double-sided disk.

    Pros And Cons of Magnetic Disk

    The magnetic disc is the most common direct-access secondary device, as we all
    know. The magnetic discs are also the device's most popular online secondary
    storage, available in various sizes. In addition, they might be portable or fixed in
    their storage devices or disc drives.

    There are various advantages and disadvantages of magnetic disk memory.

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