Optical Media Key Revision Points

Optical Media In size order: CD – 700MB DVD – 4.7GB Blu-Ray – 25GB Variations: Each of the above can come in 3 formats: ROM e.g. BD-ROM Read Only R e.g. DVD-R Can be written to once RW e.g. DVD-RW Rewritable (can write to many times)

Operation All optical media work on the same principle Learn these steps! Data on the CD/DVD/Blu Ray stored as microscopic indentations called pits Disk spins Arm/rail containing a laser moves in and out over the spinning disk A laser beam is shone onto the disk where it hits a pit or land(flat area) The reflected beam translated into binary

Benefits/Drawbacks Benefits Drawbacks Relatively Cheap (per GB of data) Low capacity compared with modern USB flash drives Portable Increasing Internet speeds have made cloud storage an alternative for backing up personal data Water/shock proof Easily scratched

Textbook and Firefly Textbook page 7