What is the CD-RW?
The CD-R/RW, properly referred to as Compact Disc Rewritable, is the first memory media in the CD family with rewriting capability. CD-RW, unlike CD-R, performs recording by making use of phase change materials in its recording layer that, when irradiated by a laser beam, can be erased (crystal phase) and recorded (amorphous phase). Then by means of differences in their reflectivity, the data is read. This enables repeated overwriting of data 1,000 or more times.

The CD-RW, compared with press-produced CD-ROMs or with the CD-R, which uses dyes, can be characterized as having a lower light reflectance from the media. This is because originally, the CD standard did not anticipate the development of recording materials using phase change. Because of this, the CD-ROM drives or CD players used in the present market cannot be used to read CD-RW media. However, the Optical Storage Technology Association (OSTA), an optical disc industry association in the United States, has authorized a program known as MultiRead. In the future, CD-ROMs, DVD-ROMs and CD players bearing the MultiRead logo will be able to read CD-RW media.
Presently, numerous manufacturers of CD-ROM and DVD-ROM drives have already agreed to this standard, and some companies have begun shipping MultiRead compatible drives. In addition, a number of software companies are shipping software products that support the random write-compatible file system which has the functions of the UDF (Universal Disk Format). This will enable writing and deletion of data onto floppy disks or hard disks by dragging and dropping.



    Recording
    surface of
    CD-RW
    Recording
    surface of CD



    Structure of CD-RW
    Structure of CD-RW image