CDRWs - How do they work?

[dec0y]

I read a post about how Vinyl differs to CDs, but can anyone explain how a CD can be written to again (CDRWs) when they are read as physical pits. I take it there is only so many times a CD can be written to again? And hows does the formatting of a disc work? Are the pits removed, or is it just as a harddisc works, with entries being deleted from a file allocation table. Thanks!

[sideymun]

Firstly a CR-RW does not store data as a series of physical pits and lands instead it uses different material reflectivity to represent ones and zeros. If you look at the underside of a CD-RW you'll see that it looks very different to a regular CD (much less reflective and different in colour), this is because the writing surface consists of a very thin layer of alloy that can change its reflectivity. Using a super hot laser(twice that used for CD-R) the writer can change the reflectivity of the surface. It is this variable reflectivity that is used to store the data. A lower power laser is used to return the surface to its original state and hence allow the CD-RW to be rewritten. I hope this answers your question.

[dec0y]

Yep! Thanks!