CD vs DVD

Could you please grab me a disc? Sounds easy doesn't it? But, nothing ever seems to be easy with computers. And discs are no exception. There are a lot of variations of discs you could grab in this scenario.

Compact Discs: CD-ROM (read only media), CD-R (recordable), CD-RW (re-writable); and Digital Discs: DVD-ROM and DVD-R and DVD-RW. There's a new smaller sized business card CD and a 2" diameter CD. You'll probably recognize CD-ROM and DVD-ROM from their more common names of CD and DVD.
If the terms aren't familiar, don't worry this is a rapidly changing arena. DVDs (especially for music) change faster than I can type. Remember the days of 8-Tracks and Cassettes … well, that's where we're at.

It all started with a CD-ROM that allowed us to read software and music from a CD. Then came the CD-R - a CD that can be written to but not erased. Following was the CD-RW that can be erased and written to multiple times. They all store an incredible 650 megabytes of data or 74 minutes of music.

Nevertheless, we weren't happy. We wanted movies and they were too big for our CD. Enter the DVD. It holds enough for a full-length movie - 17 times more than a CD.

Laser technology is what makes it all possible. Data is stored on CDs through pits, or tiny indentations. To read the disc, the drive shines a laser onto the surface. The laser reads whether the area underneath is indented with a pit or if it's smooth (written to or not written).

CD-Rs and CD-RWs use different methods for recording. Both record changes based on temperature. The CD-R utilizes a dye that is "burned" by a laser and the CD-RW disc uses a metallic coating that is melted.

A laser burns pits into the dye of a CD-R leaving it permanently changed which is why they can not be erased. CD-RWs utilize a metallic base that can be melted and remolded allowing for multiple "burns". By changing the temperature of the writing laser, the data on the disc is changed. Hence the term "burn a disc".

Your 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. The advantage in a DVD player is that it can play everything, CDs as well as DVDs.

When you figure all that out move on to your stereo. We now have Digital Audio for the Consumer. This refers to CD recorders that connect to a home stereo system. In other words, move over cassette deck - CD drives are stereo ready for recording.
By the way, hard drives are already out there for our Home Entertainment Systems. If you use TiVo (an automatic system to record your favorite TV shows) your hard drive is already connected.

Funny, but suddenly I miss my transistor radio.