Other Digital Audio Devices 615coating, silver or gold, to make the surface more refl ective. CDs created with CD-Rs are
compatible with all other computer CD-ROM drives.
Oddly enough, a “ premier price ” situation has developed with blank CD-R discs.
The requirements for recording computer data are more onerous than for sound
recordings; after all, your sound system does not shut down if there is a mistake in a tiny
fraction of a musical note. This should mean that any blank CD good enough for data
recording should certainly be good enough for audio. Some shops, however, will try to
sell audio-grade CD-R blanks at a very substantial premium.
The rapidly growing use of CD-R/RW has spawned a whole set of new terms that are
probably better known to computer users than to audio enthusiasts. Some of the more
important terms that have not been explained so far are summarized here.
Disc at once (DAO): A CD-R/RW writing mode that requires the whole of the data to be
written in one uninterrupted session. Comparetrack at once, incremental writing.
Finalized disc : A CD-R disc that has had its overall lead-in and lead-out information
written so that no further sessions can be recorded.
Fixation : The set of actions used at the end of a writing session on a CD-R drive.
Fixation writes lead-in and lead-out information and creates a table of contents for the
disc so that the disc can be read on a normal CD-ROM drive or audio CD player. If the
optionof fi xation for append is used, further sessions can be added to the disc until it is
full. See alsofi nalized disc.
Incremental writing or packet writing : A method of writing data to a CD-R or CD-RW
disc in which several sets of data can be written in each track. This reduces the effect of
the overhead of 150 recorded blocks that are used for run-in, run-out and linking.
Lead-in : A section of all CD ROM or music discs, prerecorded, CD-R or CD-RW,
that contains information on the data or music contents. The lead-in area immediately
precedes the recorded area. For a fully recorded disc, the lead-in contains the table of
contents.
Lead-out : A section of all pr-recorded compact discs that follows the recorded area (on
the outer rim of a fully recorded disc). On the CD-R or CD-RW discs, the lead-out is not
created until the disc is declared as fully recorded (preventing further recording). With no
lead-out, the disc cannot be replayed on music players, and some older CD-ROM drives
on computers may not accept it.