Optical Drives

Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs) are mainstream storage formats for music and video retail.

All types of optical media use a laser to read the data encoded on the disc surface
marketed as being hard-wearing, but scratches can render them unreadable
can be used as storage media for PC data
Each disc type is available in recordable and rewritable formats:
- Basic recordable media can be written to once only in a single session
- Multisession recordable media can be written to in more than one session, but data cannot be erased
- Rewritable media can be written and erased in multiple sessions, up to a given number of write cycles

Capacity and Speed

Each optical disc type has different capacity and transfer rate:
- CD has a maximum capacity of 700 MB
  - available in recordable (CD-R) and rewritable (CD-RW) formats
  - base transfer rate of a CD is 150 KBps
- DVD has a capacity of 4.7 GB for a single layer, single-sided disc up to about 17 GB for a dual-layer, double-sided disc
  - base transfer rate for DVD is 1.32 MBps
  - 9x CD speed
- Blu-ray has a capacity of 25 GB per layer
  - base speed for Blu-ray is 4.5 MBps
  - maximum theoretical rate is 16x (72 MBps)
Optical drives are rated according to their data transfer speed
- can perform recording/rewriting is marketed with three speeds, always expressed as the record/rewrite/read speed
  - E.g., 24x/16x/52x

An internal optical drive can be installed to a 5.25-inch drive bay and connected to the motherboard via SATA data and power connectors
external unit would be connected via USB (or possibly eSATA or Thunderbolt)
- typically require their own power supply, provided via a supplied AC adapter
Some drives use a tray-based mechanism, while others use a slot-loading mechanism

New drives are generally multi-format
- may see older drives with no Blu-ray support
Consumer DVDs and Blu-rays feature digital rights management (DRM) and region-coding copy-protection mechanisms
- Region coding, if enforced, means that a disc can only be used on a player from the same region
  - region can usually be set using device properties
  - firmware normally prevents this from being changed more than a couple of times