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What is a CD-ROM?

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. CD-ROM Technology. Data is written by etching pits into the surface of the disk

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What is a CD-ROM?

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  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

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