Optical Storage
By Matt Lay
Optical Storage
Optical Storage is optical media which includes both CD'S and DVD'S. Optical Storage is very cheap and very portable in general. They are also very durable if looked after well. Data is recorded by making marks in a pattern that can be read back with the aid of light, usually a beam of laser light precisely focused on a spinning disc.
CD
Cost; Very Cheap, 50 CD'S for £12 Capacity: 640 MB Access Speed: Up to 7.6MB/S Portability: Easy to carry in a portable bag Durability: Depends on how stored can last up to 100 years, but can start to degrade within 18 months. Reliability: Good for medium term but degrades over time. Typical Use: For software or for making backups.
DVD
Cost: Very Cheap, 50 x 4.7GB disks for £15 Capacity: 4-17 GB Access Speed; 16 MB/S Portability: Easy to carry in a large pocket bag Durability: Recordings last from 2-15 years. Reliability: Good for medium term, but degrades overtime. Typical Use: Backup items where high capacity is needed.