1. What is a CD-ROM?  5 inch disk  Holds up to 700 MB  Up to 74 minutes of audio  Are coated with aluminum  Most popular media used for software distribution  Optical storage media

2. CD-ROM Technology  Data is written by etching pits into the surface of the disk  Areas that are not pitted are called “lands”  Light is beamed to the disk  The reflection is interpreted by the processors as either data or sound  Table 13.1: CLV and CAV  TrueX / MultiBeam

3. Performance Factors  Drive speeds up to 100x (100 times faster than a standard audio CD)  Rated drive speeds are actually maximum speeds  Up to 15 MB/sec transfer rate on 100x (usually much slower)  Average access time around 80 ms  Buffer / cache  CPU Utilization  DMA

4. CD-ROM Drive Interfaces  SCSI  Best performance and flexibility+most expensive  IDE/ATAPI  Most common interface. Good performance at a lower cost  Parallel port  Convenient and easy to install. Can be expensive  USB port

5. Other CD Drive Features  Drive sealing  Self-cleaning lenses  Internal vs external

6. Writable CD-ROM Drives  CD-R  WORM (Write Once Read Many) drives  Excellent for burning “Masters” of data or music  Disk is not the same as CD-ROM  CD-RW  Can be rewritten at least one thousand times  Possible use for regular backups?

7. DVD (Digital Versatile Disk)  DVD-Video contains only video programs  DVD-ROM used as a data storage medium for PCs  Backwards compatible (will play CD-ROM and audio CDs)

8. DVD Specifications  Single sided single layer holds up to 4.7 GB data  Single sided dual-layer up to 8.5 GB data  Double sided single layer up to 9.4 GB  Double sided dual-layer up to 17 GB

9. Other CD Technologies  Enhanced Music CDs  Contains music and data. Sometimes called CD Plus or CD Extra  PhotoCD  Sold by Kodak as a photo archiving media  Divx  Short lived technology, already obsolete

10. Caring for Optical Media / Drives  Dirt, scratches, fingerprints  Deep scratches  Cache size  Color combination or cd-r  pp 767-769