Compact Disc (CD)
What is a Compact Disc (CD)?
A Compact Disc (CD) is a plastic disc used to store digital data. Introduced in the 1980s by Philips and Sony, CDs were a significant advancement in data storage and audio technology, replacing audio cassette tapes and records. CDs mainly store music but they can also be used to store other forms of data such as photos, videos, and computer software.
Who invented the Compact Disc?
The Compact Disc (CD) was jointly developed and invented by Philips and Sony in the 1980s.
How does a Compact Disc (CD) work?
A CD works by a process of reflection. The CD player uses a laser beam to read data from the disc. The beam is reflected by the disc's surface, and these reflections are interpreted as data. CDs are made up of a series of tiny bumps and flat areas, representing the binary data of 0s and 1s.
What type of laser is used in a CD player?
The type of laser used in a CD player is a low-power infrared laser.
What is the storage capacity of a standard Compact Disc (CD)?
A standard Compact Disc (CD) has a storage capacity of about 700 megabytes, or approximately 80 minutes of uncompressed audio data.
Are there types of CDs with larger storage capacity?
Yes, there are different types of CDs such as a CD-ROM, CD-R, and CD-RW, each with varying storage capacities and functionalities. The storage capacity can range up to 870 Megabytes or 99 minutes of audio data.
What is the physical structure of a Compact Disc like?
A CD is made of a 1.2 mm thick disc of polycarbonate plastic, coated with a thin layer of aluminium to make it reflective. It also has a protective lacquer layer to prevent damage to the data layer. The digital data are stored in a spiral track etched into the disc.
How is the data arranged on the CD?
The data on a CD is arranged in a single, continuous spiral track, starting from the inside and moving towards the outside of the disc.
What is Red Book standard in relation to Compact Discs (CDs)?
The Red Book standard is a set of technical specifications for audio CDs (Compact Disc Digital Audio). It defines the format of audio data, physical parameters of the disc, and the methods for storing and retrieving data. It was established by Philips and Sony in 1980.
What are some other color book standards?
Apart from the Red Book, there are several other color book standards including the Yellow Book for CD-ROMs, the White Book for Video CDs, the Blue Book for Enhanced Music CDs, and the Green Book for CD-interactive format.
What is CD-ROM?
CD-ROM stands for Compact Disc Read-Only Memory. It's a type of CD that can store data that can be read by a computer but cannot be modified. A typical CD-ROM can hold up to 700 MB of data.
How is a CD-ROM different from a CD-R?
The difference between a CD-ROM and a CD-R is that data on a CD-ROM is pre-pressed onto the disc and cannot be changed, while data can be written onto a CD-R disc by a user but cannot be rewritten once it's written.
What are CD-R and CD-RW?
CD-R and CD-RW are types of writable CDs. CD-R (Compact Disc-Recordable) allows users to write data onto the disc once, whereas CD-RW (Compact Disc-ReWritable) allows users to write and rewrite data multiple times.
What is typically the storage limit for a CD-R or CD-RW?
Typically, both CD-R and CD-RW can store up to 700MB of data, or approximately 80 minutes of audio.
How are CDs manufactured?
CDs are manufactured by creating a glass master disc, a metal stamper, and then pressing that stamper into heated polycarbonate plastic to form the CDs. The CDs are then coated with a thin layer of aluminum and lacquer, and finally, the disc is printed and packaged.
What materials are CDs typically made of?
CDs are typically made of a polycarbonate plastic disc, a thin layer of aluminum for reflectivity, and a protective lacquer layer.
Can CDs degrade over time?
Yes, CDs can degrade over time due to physical damage, heat, humidity, UV light exposure, and chemical reactions with the disc's materials. This is often referred to as "disc rot".
How can one prevent CDs from degrading?
To prevent CDs from degrading, they should be stored in a cool, dry place, out of direct sunlight, and handled carefully to avoid scratches and contaminants.
How do you care for and maintain CDs?
To maintain CDs, handle them properly by touching only the edges and the center hole to avoid fingerprints on the surface. Store them in a cool, dry place away from direct sunlight. Wipe them clean with a soft, lint-free cloth from the center outward.
How can you repair a scratched CD?
You can repair a lightly scratched CD by gently rubbing it with a soft cloth or applying a mild abrasive such as toothpaste or baking soda, then rinsing and drying. Deep scratches, however, might require professional repair or might be irreparable.