Compact disk-read only memory (CD-ROM)
Removable disks, 640 MB per disk
Seek time about 100 msec (optical read head is heavier and slower)
Higher latency (3000 RPM) and lower data-transfer rates (3-6 MB/s) compared to magnetic disks
Digital Video Disk (DVD)
DVD-5 holds 4.7 GB , and DVD-9 holds 8.5 GB
DVD-10 and DVD-18 are double sided formats with capacities of 9.4 GB and 17 GB
Slow seek time, for same reasons as CD-ROM
Record once versions (CD-R and DVD-R) are popular
data can only be written once, and cannot be erased.
high capacity and long lifetime; used for archival storage
Multi-write versions (CD-RW, DVD-RW, DVD+RW and DVD-RAM) also available
Compact disk-read only memory (CD-ROM)Removable disks, 640 MB per disk Seek time about 100 msec (optical read head is heavier and slower)Higher latency (3000 RPM) and lower data-transfer rates (3-6 MB/s) compared to magnetic disksDigital Video Disk (DVD) DVD-5 holds 4.7 GB , and DVD-9 holds 8.5 GB DVD-10 and DVD-18 are double sided formats with capacities of 9.4 GB and 17 GBSlow seek time, for same reasons as CD-ROM Record once versions (CD-R and DVD-R) are populardata can only be written once, and cannot be erased.high capacity and long lifetime; used for archival storage Multi-write versions (CD-RW, DVD-RW, DVD+RW and DVD-RAM) also available
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