Storage Devices - INFO 1

HideShow resource information
  • Created by: Hannah
  • Created on: 15-01-13 19:46

Hard Disks

Hard disk drives are the main internal back store found inside a computer.

  • They are rigid circular plates that have been magnitised (usually several disks)
  • Each disk contains concentric tracks that are divided into sections where data is stored.
  • Most disks store data on both sides
  • The disk rotates at between 5,400 and 10,000 revolutions per minute (rpm) and the read/write heads float just above the surface of the disk
  • If there is a problem with the hard drive, all of the data could be lost.
  • External hard drives are quite affordable and a good option for storing large amounts of data (+ they are portable)

The main benefit is that they have a large capacity

1 of 5

Optical Discs

Optical discs are the main external backing store.

  • Optical discs include compact discs (CDs) and Digital Versatile Discs (DVDs).
  • They store digital data as pits on the surface of a reflective disc.
  • Data is read by a moving laser beam across the surface of the disc

There are three types of CD

  • CD-ROMs
    Can only be used to read data ('Read-Only-Memory') - 650MB
  • CD-Rs
    Sold as blank CDs and can be written on once. After that they become CD-ROMs.
  • CD-RWs
    'Read and Write' - new data can be written on to the disc.

DVDs are like CDs, but hold more infomation/data - 8.54GB

CDs --> DVDs --> --> Blu-Rays         In order of increasing capacity

2 of 5

Flash Memory

Flash memory is often sold in pen drives/memory sticks.

  • They're easy to connect to the computer through USB ports and hold between 1 and 32GB
  • Memory sticks are tough and easily let you transfer data between computers
  • Flash memory is a lot slower than a computer's RAM, but often fasted than a HDD.
  • The main disadvantage  is that they are small and can easily be lost/stolen and are more expensive then DVD-RWs

Flash memory is also used to make small memory cards

  • These come in many different shapes and sizes
  • Memory cards are used by digital cameras and some mobile phones and mp3 players.
  • Many computers come with memory card slots, which means you can use them for reading/writing files, just like a memory stick
3 of 5

Magnetic Tape

Magnetic tape can back up very large amounts of data.

  • It is often used when large amounts of data needs to be backed up, it can store up to 800GB of data
  • With magnetic tape, very large amounts of data can be stored cheaply, making them ideal for backing up hard drives or even a whole network
  • Access is slow as read/write head can't go to exact piece of data, it has to search through all (serial/sequential access)
4 of 5

Floppy Disks

A floppy disk is a circular piece of magnetised metal protected by a hard plastic sleeve.

  • The amount of data it can store is tiny - 1.4MB
  • Accessing data is slow and they only last around 6 months
  • ZIP disks are like floppies, but more reliable and solid. They can store up to 750MB, but are more expensive than floppies
  • Floppy and ZIP disks are not used anymore, they have been replaced with modern day technology
5 of 5


No comments have yet been made

Similar ICT resources:

See all ICT resources »See all Devices and Storage resources »