Secondary storage devices and

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Secondary storage devices and

  1. 1. SECONDARY STORAGE DEVICES AND MEDIA
  2. 2. MAGNETIC TAPE <ul><li>Magnetic tape is used for storing large amounts of data. </li></ul><ul><li>A recording medium consisting of a thin tape with a coating of a fine magnetic material. </li></ul><ul><li>Data is stored in frames across the width of the tape. The frames are grouped into blocks or records which are separated from other blocks by gaps.. </li></ul>
  3. 3. IMAGE OF MAGNETIC TAPE
  4. 4. FLOPPY DISK <ul><li>This is a removable disk. It is a sequential device. The tape has a beginning and an end, and to move the tape to another song later in the sequence of songs on the tape you have to use the fast forward and rewind buttons to find the start of the song, since the tape heads are stationary. For a long audio cassette tape it can take a minute or two to rewind the whole tape, making it hard to find a song in the middle of the tape. </li></ul>
  5. 5. IMAGE OF FLOPPY DISK
  6. 6. HARD DISK <ul><li>A hard disk is a large capacity rigid magnetic disk that is used for storing data. Data is read from or written to hard disk using an arm-like device known as a read/write head. This is a device that is used to write data to the disk (store it on the disk) and to read data from the disk. The access time is the time it takes for the data to be accessed. The faster the access time is the faster the seek time (time it takes the read/write head to get to a specific position on the disk). </li></ul>
  7. 7. IMAGE OF HARD DISK
  8. 8. OPTICAL DISK <ul><li>This is a type of media used for storing data. It reads data using laser beam. There are two common types of optical disks : CD and DVD. Both types use the same method to read the data. A low-powered laser uses a lens to focus the laser beam on a part of the disk. Under the plastic layer on the reflective side there are areas that reflect light differently. The drive can detect these differences and converts theses differences into ones and zeroes that can be interpreted by the computer. </li></ul>
  9. 9. IMAGE OF OPTIC DISK
  10. 10. COMPACT DISK(CD) Click on image for information on how a CD work.
  11. 11. DIGITAL VERSATILE/VIDEO DISC(DVD) Click on image to read about how DVD work.
  12. 12. MAGNETO- OPTICAL DISKS <ul><li>This is a storage device in which information is stored using optical and magnetic methods. The surface of the disk is covered in a special alloy. When the crystals in this alloy are heated up using a laser. They behave like those found in normal magnetic storage media. Therefore, data can be recorded on the disk using magnetic heads. Magnetic- Optical Disk is read using a laser of lower intensity than the one used to heat up the disk during recording. </li></ul>
  13. 13. MAGNETO- OPTICAL DISK
  14. 14. CRITICAL THINKING EXERCISE <ul><li>A company has a 50mb file to back up. Select a storage medium that is best suited for backing up the file and explain your choice of this medium. </li></ul><ul><li>A software development company has decided to distribute its software on CDs instead of disks. Give two advantages of the use of CDs for distributing software over the use of disks. </li></ul>
  15. 15. REFERENCES <ul><li>Information Technology for CSec by Kelvin Skeete and Kyle Skeete </li></ul>

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