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The Digital Versatile (Video)
Disk, or DVD, is yet another example of the IT industry's
ability to make one technology operate on an ever increasing scale.
A DVD drive is written,
constructed and read in an almost identical fashion
to that of a standard CD-ROM. The main difference
is that the DVD drive uses a single frequency red
laser to read and write data.
Because a laser light
has a shorter wavelength than red light, data
bits can be packed tighter on the same media.
This subtle change in technology
allows a DVD to store an amazing 2.6GB of data
per side. I say per side because DVDs
are also capable of holding data on both sides
of the disk.
DVD technology also employs
a specific form of data compression that requires
them to be read in a DVD drive only. CD-ROM
drives are not capable of reading DVDs,
but any DVD drive is capable of reading
Blue Laser CD-ROMs / DVDs
For those of you who are intrigued, a DVD drive is capable of handling so much data simply because of a slightly smaller wavelength of laser light. If you remember back from your physics classes (I'm sorry to have to do this) you will remember that as you shorten the wavelength of light, you pass through the visible spectrum from red to yellow, to green, to blue. Going beyond that you get away from visible light in to ultraviolet radiation and so on.
Technology is being developed today that will use a blue light laser to read and write to CD ROM like disks. It is estimated that because of the vastly smaller wavelength of blue light compared to red light, a CD-ROM like disk may be able to hold 15GB of data, per side.
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CertiGuide to A+ (Core Hardware) (http://www.CertiGuide.com/aplush/) on CertiGuide.com
Version 1.0 - Version Date: December 6, 2004
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