optical storage devices
How it works
•An optical disk is a high-capacity storage medium. An optical drive uses reflected light to read data.
•To store data, the disk's metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
•When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).
Optical storage devices:
•CD-ROM: compact disc ROM (Read Only Memory)
–Capacity: 650MB
•CD-R: compact disc recordable
•CD-RW: compact disc rewritable
•DVD: digital versatile disc
–Capacity: 4.7GB – 17GB
•DVD-R
•DVD-RW (2 versions: + (plus) and
– (dash)
DVD (Digital Versatile Disk):
–Allows up to 17 gigabytes of storage (from 4.7 GB to 17 GB).
–Compatible with older CD-ROM technology.
–The four versions of the DVD:
