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Optical Storage

How they work

How they work

Note: You are not required to know how optical devices work for the IGCSE ICT Specification, but it probably helps you remember the advantages and disadvantages 🙂


Compact Discs – CDs


CDs were introduced in the 1990s in order to fill the demand for a cheap and easily transportable method of data storage. They contain one of two types of data:

  • audio data, readable by a CD player or a computer up to 70 minutes long
  • binary data, readable by a computer , up to 700MB


  • Music Albums
  • Photo and documents backup
  • Device driver & software shipped with hardware


  • Cheap per MB storage
  • Easy and cheap to ship via the mail
  • Wide compatibility


  • Not suitable for high resolution image / video backup
  • Can’t store a full Movie on it
  • Easy to scratch / break
  • Slow read / write speed




Digital Versatile Discs – DVDs


DVDs were introduced to fill the demand for higher capacity storage than was available using CDs.

They use a narrower laser beam, which allows more storage capacity than a CD.


  • Feature length films (Full movies)
  • Operating System storage
  • Larger modern games / software
  • Image and Video file backup


  • Larger storage capacity than CDs
  • Can store full standard quality movies
  • Faster R/W speeds than CDs
  • Very cheap per MB storage


  • Can storage HD / 3D Movies
  • Can’t do a full Hard Drive backups
  • Can be scratched / broken easily






Blue ray discs allow cheap distribution of HD videos and games, though they are largely being replaced by cloud streaming.

As games began to include larger open world environments and televisions increased their resolutions, there developed and increasing demand for larger storage capacity optical devices, and as a result the Blue-ray disc was invented.


  • 3D and Full HD Movie Storage
  • Games storage for high end games consoles
  • HD movie and image backup
  • Hard Drive backup


  • Only Optical disc large enough for hard drive backups
  • Faster R/W speed than DVD/CD


  • Still not widely supported by many computers




Activity – The Story of Optical Media Presentation

Using Powtoon ( or other similar presentation / animation software ) create an animation showing the story of optical media.

Your animation should include:

  • How Optical media works
  • What the different optical media devices are, their uses and pros / cons.
  • What lead to the development of the next technology
Powtoon Prezi