Secondary Storage Devices

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)

Can’t access YouTube? Click here for the Google Drive Version

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.

Advantages

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

Disadvantages

Not very portable
Can be damaged if dropped

This technology is used in…

HDD Hard Drive

YouTube tutorial video

Source: Wikipedia

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.

Advantages

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

Disadvantages