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Storage Devices

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This ppt include optical, magnetic and solid storage devices.

This ppt include optical, magnetic and solid storage devices.


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  • 1. Storage Devices
    By : Emily 10BW
  • 2. Optical storage device - CD
    CD-ROM : CD Read only memory. When you buy a CD from a store, you can read it, but you can’t save any thing on it.
    CD-R(WORM) : CD Write once read many. You are able to save to this disk one time, so you can storage an application or your data on it. After you have saved on it once, you can read it many times but can’t save on it again.
    CD-RW : CD Read Write. You can save your data over and over again, like a floppy disk.
    Advantages :
    • Small and portable
    • 3. Very cheap to produce
    • 4. Most computers can read CDs. If there is no CD drive, a DVD drive can usually read them
    • 5. Fairly fast to access the data - quicker than a floppy disk or magnetic tape
    Disadvantages :
    • Fairly fragile, easy to snap or scratch
    • 6. Smaller storage capacity than a hard drive or DVD
    • 7. Slower to access than the hard disk.
  • Optical storage device - DVD
    DVD-ROM : A new type of read only compact disc that can hold a minimum of 4.7GB.
    DVD-R : can only record data once then the data becomes permanent on the disc. This disc can’t be recorded onto second time.
    DVD-RW : The data on a DVD-RW disc can be erased and recorded over numerous times without damaging the medium.
    DVD-RAM : can be recorded and erased repeatedly but are only compatible with devices manufactured by the companies that support the DVD-RAM format. DVD-RAM discs are typically housed in cartridges.
    Advantages :
    • Very large storage capacity
    • 8. DVD players can read CDs
    • 9. DVDs are now mass produced so they are relatively cheap
    • 10. Sound and picture quality is excellent, making them ideal for storing films with video and sound.
    Disadvantages :
    • DVDs do not work in CD drives
    • 11. There is no single standard of DVD
    • 12. They can be easily damaged by breaking or scratching
  • Optical storage device – HD DVD
    HD DVD-R : the writable disc variant of HD DVD, available with a single-layer capacity of 15 GB or a dual-layer capacity of 30 GB.
    HD DVD-RW : the rewritable disc variant of HD DVD with equal storage capacity to an HD DVD-R.
    HD DVD-RAM : the proposed successor to DVD-RAM for random access on optical media using phase-change principals. It would hold 20 gigabytes per layer instead of 15 gigabytes for HD DVD-R, due to differences in recording methods used, yielding a higher density disc.
    Advantage :
    • Cheaper than a Blu-ray
    • 13. Greater movie support than the competition
    • 14. manufacturers can produce the high definition players for much less than Blu-ray.
    • 15. a number of prominent manufacturers have pledged support to the player and format.
    Disadvantage :
    • Thought it’s cheap but there’s a lot of great things that didn’t have in HD DVD.(e.g. charity, Four months worth of groceries for the average bachelor est.)
    • 16. Region coding still unclear
    • 17. Films aren’t cheaper, even if the player is
    • 18. Xbox 360 version features no HDMI
  • Optical storage device –Blu-ray
    Blu-ray : medium designed to supersede the standard DDVD format. Its main uses are for storing high-definition video, PlayStation 3 video games, and other data, with up to 25 GB per single layered, and 50 GB per dual layered disc. The disc has the same physical dimensions as standard DVDs and CDs.
    Advantage :
    • Huge storage capacity
    • 19. Mandatory Managed Copy
    • 20. Backwards compatibility
    • 21. Clear than DVD
    • 22. Can put it in the DVD player
    Disadvantage :
    • Very expensive
    • 23. The cost of film
    • 24. Presently greater number of movie titles are available on DVD's
    • 25. Future uncertainty (even without HD-DVD)
    • 26. Long reading times of the discs
  • Magnetic storage device – Floppy disk
    Floppy disk : It can only store up 1.44Mb of data. All disks must be formatted before data can be written to the disk. Formatting divides the disk up into sections or sectors onto which data files are stored.
    Advantage :
    • Small & light – easy to carry
    • 27. Cheap
    • 28. Useful for transferring small files
    • 29. Can be used many times
    • 30. Security tab to stop data from being written over
    Disadvantage :
    • Easy to be damage
    • 31. Small storage capacity
    • 32. Many new computer don’t have floppy disk drives
    • 33. Can transport viruses from one machine to another
    • 34. Slow to access and retrieve data when compared to a hard disk
    • 35. Data can be erased if the disk comes into contact with a magnetic field
  • Magnetic storage device – Magnetic Tape
    Magnetic Tape : uses 'serial access' to find a piece of data. It works in much the same way as a video tape. To find a specific piece of data, you have to start at the beginning of the tape and continue fast forwarding until you get to the piece of data that you need.
    Advantage :
    • relatively cheap per megabyte of storage
    • 36. can store large amounts of data - over 100 Gb
    • 37. can be set up to do the back up overnight or over the week
    Disadvantage :
    • serial access so can be quite slow to access data
    • 38. need a special piece of equipment to record and read the data on the tape
  • Magnetic storage device –Hard disk
    Hard disk : the main storage device in computer. It is a bit like a filing cabinet: all of your data files and applications software are stored on it. It contains a number of metal platters which have been coated with a special magnetic material. The data is stored in this magnetic material.
    Fixed hard discs : Used to store operating systems, software and working data. Any application which requires very fast access to data for both reading and writing to. Not for applications which need portability. Used for online and real time processes requiring direct access. Used in file servers for computer networks.
    Portable hard discs : Any application which requires extremely large storage capacity where speed of access is not an issue. Uses serial access for reading and writing. Used for backups of file servers for computer networks. Used in a variety of batch processing applications such as reading of bank cheques, payroll processing and general stock control.
    Advantage :
    Disadvantage :
  • 39. Solid State device –Flash Memory &Memory Stick
    Flash Memory : Memory sticks are available from 1 Gb up to 8 Gb. They are typically small, lightweight, removable and rewritable. They consist of a small printed circuit board which is encased in plastic or metal casing. They usually have a removable cap which covers and protects the part of the stick which is inserted into a USB port.
    Advantage :
    • Hold more data than CD
    • 40. More reliable than floppy disk, because they have no moving part
    • 41. More compact and portable than floppy disks or CDs/DVDs.
    • 42. Being developed with fashionable looking outer casings and are almost becoming a 'fashion accessory‘.
    Disadvantage :
    • Lost easily
    • 43. The metal part which is inserted into the USB port can be snapped off if they are handled roughly
    • 44. More expensive than floppy disks, CDs and DVDs