Discuss the various types of optical disc systems available and how they differ from each other and from magnetic systems.
There are various types of optical disc systems available such as CDs and DVDs. They store data optically by using laser beams instead of magnetically. Typically 4 and a half inch circles although smaller discs and custom shapes are also available. Divided into tracks and sectors like magnetic disks but a single grooved spiral track.Can be read-only recordable or rewritable. It has a high capacity of 650MB. Spots on the disc or pits are used to represent the data's 1s and 0s. The unchanged areas on the disc are called lands. These pits can be molded into the disc surface or created by changing the reflectivity of the disc.
Read only discs have both CD ROM and DVD ROM discs. Thet can be read from, but not written to, by the user. Then you have Recordable discs which can be written to, but cannot be erased or reused. CD-R discs are commonly used for back up, sendind large files to others and creating custom music CDs. Finally you have rewritable discs which can be recorded on, erased and overwritten just like magnetic disks.