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Backing Storage Media and DevicesMomina

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Portable Hard Disks

Fixed Hard Disks

Blu-ray Disks

Flash memory cards

CD ROMS/ DVD ROMS

CD R’s/DVD R’s

Magnetic tapes

Memory sticks

Minidisks

CD RWs/DVD RWs

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DVD RAMS

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Magnetic Tapes

• Magnetic tapes are thin strips of plastic which are coated with a magnetic layer.

• These thin strips are then fed through a read/write head mechanism.

• This data on the magnetic coated tape is stored as magnetised bits.

• The data is stored in sequence, causing data retrieval fairly slow.

• They can be used in batch processing, utility billing systems, payroll applications and making back ups.

ADVANTAGES AND DISADVANTAGESClick for:

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Magnetic Tapes

Advantages DisadvantagesCheaper than using disks Slow accessRobust + encased in a cartridge

In order to update, a new tape needs to be created.

Easier to remove + keep away from the computerData transfer is fast

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Fixed Hard Disk Drives

• This is one fixed disk in the computer. It is essential when fast data access times and fast data transfer rates are required.

• Mounted on a spindle. This is operated by a motor which makes the disk spin very quickly.

• It is used to store the disk operating system, software programs, and data files.

• Used in robotics and rocket launching.

Advantages DisadvantagesData transfer rate is fast Easily damaged.

Data access time is fast

Have a large capacity

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Portable Hard Disks

• The job of a portable hard disk drive is the same as the job of the fixed hard disk drive, they only difference is : ITS PORTABLE!

• They can store up to more than 100GB.• They are often used as backup media. • They come particularly in handy when transferring server

software.

Advantages DisadvantagesData access time is fast Dropping could damage them

Data transfer rate is fast Transfer rate is not as fast as the transfer rate for Fixed hard Disk drives.

Large capacity More expensive

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CD ROMs/DVD ROMs

• ROM stands for read only memory. • The main difference between CD’s and DVD’s is their memory.

DVD’s have a much greater capacity as opposed to a CD. • DVD writers use a shorter wavelength laser; so the pit on the

disk is much smaller. • CD ROMS are used for music albums and DVD ROMs are used

for movies.

Advantages DisadvantagesDVD has a greater capacity then a CD

Data transfer rates are slower than a hard disks’

CDs are cheaper to buy Data access times are longer than a hard disks'

Both hold more data than a floppy disk.Both are cheaper and more robust than hard disks

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CD R’s and DVD R’s

• R stands for Recordable. Data can only be written on them once; after that they become ROMs.

• They can be used for home recording• They can be used for storing and transferring data.

Advantages DisadvantagesCheaper than CD/DVD RW s

Can only be recorded on once.

Once they are used; there is no chance that by accident something will rewrite over it.

Not all CD players recognize CD R s

Optical backing storage media:

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CD RW s/DVD RW s

• RW stands for rewritable.• The surface of these disks is a metallic alloy

layer. This alloy is a phase change alloy. It can be amorphous or crystalline. The power of the laser changes spots on the surface from one phase to another by causing it to melt of freeze.

Advantages Disadvantages

Can be used more than once. Cost makes them impractical for use.

Different versions of the files can be written.

Files can be over written by accident

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DVD RAM s

• Digital Versatile Disk Random Access Memory. much longer lasting than other forms of optical media.

• Used for storing data.• In camcorders; they can be used for recording video.

Advantages Disadvantages

Greater capacity than CD and DVDs Not compatible with most DVD players

More durable than DVDs More expensive than other types of DVD media.

Optical backing storage media:

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Blu-ray Disks

• Largest Capacity of all optical disks- 25 GB, 50 GB, 100 GB.

• Uses a shorter wave length. It uses the light closer to the blue/violet spectra.

• Coated in lacquer which prevents damage to the surface . They are used in home video game consoles and

camcorders.

Advantages DisadvantagesStore more than other optical media

Very expensive

Data transfers are high Problems with encrypting.Access speeds are higher with blu-ray players

Optical backing storage media:

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Minidisks

• Made up of hybrid media. It uses both magnetic and optical methods to record data.

1. Laser used to heat one side of the disk, making it easier for the disk to be magnetized.

2. Magnet head used to magnetise spots on the other side of the disk.

3. Data can only be read by laser 4. They are encased in a cartridge.• Used in portable music players.

Advantages Disadvantages

Can be recorded over more times than any other media.

Slower transfer rates

More robust than other optical materials.

Hold less data than other music players More expensive than portable players.

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Memory sticks

• Can store many GB’s• They work by drawing power from the

computer via USB interface. • Transport files + back up data

Advantages Disadvantages More compact More expensive per GB.More robust Cannot be protected.Do not need software drivers to operate

Solid state backing storage:

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Flash Memory Cards

• Form of EEPROM (electronically erasable programmable read-only memory)

• They usually store photographs in cameras. We better know them as SD cards.

Advantages DisadvantagesMore compact More expensive per GB

Can only be used for a particular number of optionsLower storage capacity then hard disks.

Optical backing storage media: