The reason that the TotalSpace of a CD-R is set to maximum
659 Mb is because most CD-Writers are not able to write more
than this value to a CD-R (because of mechanical or firmware
shortcomings). Thus bigger CD-R's are useless for these CD-Writers.
Only a few CD-Writers can go beyond this 659 Mb boundary, the
most common are mentioned below.
A CD-R is in fact recordable up to the end of the physical
pre-groove which contain information so the recorder can position
the laser for recording, normally somewhere in the 77 minutes.
To be able to OverSize CD-R's the Disc-At-Once
mode of the CD-Writer is utilized. DAO
mode, instead of TAO,
must provide it's own lead-out (which now can be moved to the
very end of the CD-R).
Disc-at-Once has only been added/available with the recent generation
of CD recorders and recent firmware upgrades. At the moment
about 95% off all CD-Writers support DAO but not all of them
mode the CD-R software sends a CUE Sheet (TOC)
to the CD-Writer, this CUE Sheet holds information
needed for the leadin area (tracksizes & more). A CD-Writer
which is not able to OverSize will reject the
CUE Sheet when it contains track information
which ends past the blank media reported length. The length
is read from the pre-groove of the blank media and specifies
the last possible position where DATA can be safely written
to. A CD-Writer which is able to OverSize will just ignore this
length and will try to burn the blank media up to the end of
Keep in mind that OverSizing is not totally without risk. OverSizing
is writing DATA to a place which is outside the original CD-R
specifications. This can result that some CD readers (Audio
& Data) can have problems reading the last 90 seconds of
an OverSized CD-R. There is no garantee that the quality of
the pre-groove, dye and reflective layer, past the reported
length, is as good as it is before!
A few CD-Writer software packages warn you that it is possible
to damage your CD-Writer when trying to oversize a CD-R. At
the moment there is totally no evidence supporting this warning.
They just put it in their software just in case it happens and
they then can say that you have been warned!
Just take the following in consideration when OverSizing a
There is a possibility that it can damage the CD-Writer.
Some CD-Writers can't physically move the carriage up to
the end of the pre-groove and so can't overburn up to the
quantity of the blank.
Some CD-ROM player can't move their carriage far enough
too play an OverSized CD-R.
The quality of media can be lower than in the normal part
of the CD-R.