Storage+Devices-+CD

=CD=


 * Compact Disc abbrieviated CD is a famous storage device used since 1982
 * It peaked as the most used portable storage device until 2000
 * It is usually 120 mm in diameter and holds 700 MB of space
 * It expanded into different types of discs like CD-ROM, CD-R, CD-RW, VCD, CD-i etc.
 * Data is literally burnt onto the CD using a laser hence it is called burning a CD when writing data onto a CD
 * The data is read by the laser being reflected off the burnt space going into a sensor

Advantages

 * 1) Can hold lots of media
 * 2) Easy to carry
 * 3) Cheap

Disadvantages

 * 1) Easily damaged
 * 2) Many types of CD are easily copied causing lot of copytright issues

CD-ROM

 * A pre-burnt CD that can be written only once and then used for Reading only
 * Most popular in distributing computer software, video games etc
 * Can only be read on a computer and on a CD player but with audio only
 * Can hold up to 900 MB

Advantages

 * It is easily transportable and is compatible with any other PC or laptop
 * Can store more data than a usual CD

Disadvantages

 * Expensive
 * Easily damaged
 * Information is fixed therefore hard to update

CD-R

 * A CD that is recordable but only once, similar to CD-ROM but it is recordable by the user
 * It is an example of Write Once, Read Many (WORM) storage
 * Mostly used as a one session backup as it is WORM type storage

Advantages

 * Cheap
 * Hugely accessible for everyday use

Disadvantage

 * With WORM storage the data burnt onto it cannot be changed once written with no way of updating the data.
 * Short lifespan

CD-RW

 * This type of CD is re-writable
 * It's structure is different from other CD's making it re-writable
 * It is mostly used for backing up files or when transporting files across PC's

Advantages

 * Re-writable disc allows the user to update or correct the data recorded on the disc
 * Highly accessible and cheap

Disadvantages

 * Short lifespan
 * Slower to write
 * Not compatible with older CD players and drives (11-12 years old or more)