Optical Storage Devices

Optical storage devices work by firing a microscopic laser beam at the surface of a spinning plastic disk, such as a DVD, CD or Blu ray. The surface of the disk is a combination of flats ( representing 1s) or pits (zeros). Depending on whether the laser hits a flat or a pit the laser beam deflects differently, and this difference in deflection is recorded by a later detector.

Advantages of optical storage

  • Cheap per GB of storage
  • Portable – cheap and easy to post

Disadvantages of optical storage

  • Easy to break
  • Not always reliable
  • Slow read-write speeds

This technology is used in…

CD Players
DVD Drives
Blu-ray drives

YouTube tutorial video

Close-up of a CD surface

Optical Storage Devices Animation

Magnetic Storage ( Hard Drives, Tape Drives, Floppy Disks)

How they work

Magnetic drives work by changing the magnetic polarity of the the surface of a glass or metal platter. A read head on a actuator arm detects the polarity and the data is interpreted as either a 1 or a 0, depending on the polarity detected.


  • Very cheap per GB storage
  • Medium read/write speeds
  • Quite robust


  • Not very portable
  • Can be damaged if dropped

This technology is used in…

HDD Hard Drive
HDD Hard Drive

YouTube tutorial video

Magnetic Storage Devices Animation

Solid State Drives ( SD Cards, SSD Hard drives, Pen drives)

Solid state drives work by storing the data inside on microscopic silicon chips  called floating gate transistors. The floating gate stores electrons, and the memory cell itself can detect if electrons are stored.


  • Fast read-write speeds –  Because the data is stored directly in the silicon chip the read-write speeds are incredibly quick
  • As there are no moving parts, SSDs are very robust and can withstand being dropped


  • They are more expensive per GB than other forms of storage

This technology is used in…

Pen Drives
Pen Drives
SD Cards
SD Cards
SSD Hard Drives
SSD Hard Drives in smartphones and tablets

YouTube tutorial video


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