Copying/moving files form the hard-drive drive to CD-R

[SecretCode]

AFAIK a cd-r is a once-only disc. How a cd-rw allows you to add/subtract files is beyond my understanding - other than it just does!

Each 'bit' of a CD-R is write once. A multi-session CD-R works by burning new files into the free space, and then writing a new table of contents (effectively the directory system) that can point to files in any of the sessions, older ones as well as the newest.

CD-RWs work by having a different laser setting (possibly just a stronger one) which resets the chemical structure of the disc layer. I think you have to blank the whole disc at once.