Optical Memory
By Dexter Stagg
CDs
Cost: 24p each Capacity: 64MB Access speed: 7.6MB/s Portability: Can easily fit in laptop bag Durability: If kept in case can last upto 100 years Rewrite Ablility: None unless you by CD-RW Weakness: Fingerprints scatches and dust can ruin a disk Typical Use: Music
DVDs
Cost: 30p Each Capacity: 4-17Gb Access speed: 16MB/s Portability: Can easily fit in laptop bag Durability: Recordings last 2-15 years Rewrite Ablility: None unless you get DVD-RW Weakness: Fingerprints, dust and scratches can ruin the disk Typical Use: Films
Blu-Ray
Cost: £1.50 Capacity: a normal blu-ray can hold 25GB but some double layer ones can hold 50GB Access speed: 4.5MB/s Portability: Can easily fit in to laptop bag Durability: Lasts about 30-50 years Rewrite Ablility: None unless you get a BR-RW Weakness: Scratches, fingerprints and dust can ruin a disk Typical Use: Films