In the mid-1980s compact discs, or CDs, started gaining in popularity as audio-storage devices. Their size, convenience, capacity and sturdiness enabled them to quickly overtake other data storage formats, such as floppy disks, in popularity.
History
The use of blank CDs among consumers emerged after Sony and Phillips designed the CD in 1981 and and developed specifications for its use in digital audio systems, computer CD-ROM drives, and formats with both audio and video files.
Physical Specifications
A CD's physical specifications include a diameter of 12 cm, a thickness ranging from 1.1 to 1.5 mm, and a central opening of 15 mm.
Materials
A CD consists of a polycarbonate plastic substrate with a reflective metallic gold or silver alloy film with a protective anti-ultraviolet lacquer. Blank CDs have an extra layer of dye between the substrate and the metallic layer. A laser burns data into this dye.
CD Information Area
Three main sections make up the information area of a blank CD. The lead-in area describes disc contents and allows the CD player to synchronize itself with the following data tracks. The program area contains the data. The lead-out area marks the end of the CD and contains no data.
Formats
Blank CDs come in two main formats. CD-Rs allow you to write or burn data in one session only. CD-RW (ReWritable) allow you to erase and write in multiple sessions.
Tags: contains data