- optical drive: laser shines on disc and transition from land to pit.
- pits and bumps: less reflection (.12microns deep and .06 microns wide).
- spiral: (3 miles long, over 2 billion pits)
- CD-ROM : read only (metallic film with real pits)
- CD-R : write once (heats the metal and dye together)
- CD-RW: up to 1,000 times (alloy changes with heat)
Capacities: 650 and 700 MB
Speeds: 24 x = 3,600 KBps, 52x = 7,800 KBps