DVDs

Optical or laser storage discs come in two types: CD and DVD. CDs hold about 700 MB and are of three types be CD-ROMs (read-only), CD-R (write once) and CD-RW (rewritable).

DVDs come in the same three basic types, but the names and sizes are more variable. DVD-ROM are read only; DVD-R and DVD+R are write-once discs; and DVD-RW and DVD+RW are rewritable. (DVD-RAMs are disappearing).

Single layer DVDs usually have about 4.7 GB of storage, and two-layer DVDs have about double that capacity.

Remember that DVD+RW and DVD-RW drives can read and write CDs. However, CD-ROM drives can’t read DVD-ROMs.

Since DVDs of all kinds hold a lot more information than CDs, they are likely to take over the whole optical storage market when the fight between the different standards is over and a winner has emerged. In the meantime, you’ll find that a lot of DVD drives are both +RW and –RW.

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DVD-ROM External Drive

• Writes to CD-Rs and CD-RWs and reads DVD-ROMs
• CD-R write speed: up to 16x
• CD-RW speed: up to 10x
• DVD-ROM speed: 8x
• Hewlett-Packard

DVD-RW/DVD+RW Internal Drive

• Writes to CD-Rs, CD-RWs, DVD-R/+R, and DVD-RW/+RW
• Write to CD-R: 16x
• Write to CD-RW: 10x
• Write DVD+R/-R: 4x
• Write to DVD+RW/-RW: 2.4xv
• Memorex

CD-RW/DVD-ROM Combo Drive

• Writes to CD-Rs, CD-RWs, DVD-R/+R, and DVD-RW/+RW
• Write to CD-R: 16x
• Write CD-RW: 10x
• Write to DVD+R/-R: 4x
• Write to DVD+RW/-RW: 2x
• LaCie