Bits'n'Bytes

As heard on CJCD

Episode 27

With the cost of CD's and DVD's so low nowadays, lots of people ask me to give them a hand burning stuff to CD or DVD. Most people have no idea how CD and DVD burners work, so today I'm going to talk about CDs.

CDs were originally developed in the late '70s and early '80s and mass production of them started 'way back in 1982 with the first mass produced pop album being Abba's "The Visitors". Recordable CDs, or CDRs, were introduced in 1990 and rewriteable CDs, or CDRWs, were introduced in 1997.

In general, CDs can hold either 650 or 700 MB of data. 650 MB was the original size - meaning it could hold up to 74 minutes of music. This odd playing time was supposedly recommended so the entire Beethoven's 9th Symphony could fit on one CD. 700 MB CDs can hold up to 80 minutes of music.

CD speeds that you can see on a CD recorder are the maximum read, write and rewrite speeds a CD recorder can perform at, times 150KB/s. The highest number will be the read speed, and the lowest will be the rewrite speed.

To make a recordable CD, you need a CD burner, which uses a laser to heat up a dye in the recordable CD itself. The dye becomes two different colours - one colour, burned, may count as a 1 and the other colour, unburned, may count as a 0. This way, your computer can read the information on a CD.

Rewriteable CDs use a chemical reaction caused by the heat of the laser to create two different colours. Heating the CD to one temperature creates one colour and heating to another temperature creates a different colour.

Stay tuned next week when I talk about DVDs.

I’m Computer Dave, thanks for your time.