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DRAGONMOUNT

A WHEEL OF TIME COMMUNITY

So like, internet cafes.


cosmicpanda

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So is your FACE!

 

No?  Wait, what?

 

Did someone say something?

 

>.>

 

Our library has free wi-fi, it's really nice, so as long as you have your own computer you can stay there as long as you want (until it closes).

 

Though I bought a wireless router so I don't even have to worry about it anymore.

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Guest BaLefireP

are you kidding?  I still can't get over hard drives or cds or memory boards. I mean, how do they get programming information onto a plastic disc!?  I don't understand!!!

 

::) ::)

From How CDs Work, you learn that a normal CD uses microscopic bumps to store data. The surface of the CD is a mirror, and the bumps disrupt the mirror's perfect surface. The laser that reads the CD can detect the difference between a perfect mirror and an imperfection caused by a bump because of the difference in reflectivity. By interpreting "perfect mirror" as a "1," and "bump" as a "0," it is easy to store digital information on a CD. The bumps on a CD are molded into the plastic when it is manufactured, so they are permanent.

 

To create a writeable CD (CD-R), you need to modify the surface of a CD so you can burn data onto it, turning it into a CD-R. There are no bumps on a CD-R. A clear dye layer covers the CD's mirror. A write laser heats up the dye layer enough to make it opaque. The read laser in a CD player senses the difference between clear dye and opaque dye the same way it senses bumps -- it picks up on the difference in reflectivity.

 

To create a rewriteable CD (CD-RW), you need a dye layer that can be changed back and forth between opaque and transparent. This page discusses the special material that CD-RW's use. The material has the property that it can change its transparency depending on temperature. Heated to one temperature, the material cools to a transparent state; heated to another temperature, it cools to a cloudy state. By changing the power (and therefore the temperature) of the writing laser, the data on the CD can be changed, or "rewritten."

 

A CD-R can be read by just about any CD player. CD-RW discs are not so versatile -- lots of older CD players cannot read them.

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