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



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 Powtoon

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