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What is a CD

What is a CD

A compact disc (CD) is a circular disc introduced by James Russell. It is 4.75 in diameter, which is a flat, round, portable storage medium used to record, store and playback audio, video, and other data. On 17 August 1982, in Germany, the first CD was created at a Philips factory. Sony and Philips proposed the CD standard, and in 1993, the technology was introduced to the U.S. It can store data up to 700 MB or 80 minutes of audio. It stores data as small notches and read with the help of laser from an optical drive, and the notches are converted into usable data by drives.

The first CDs were able to store only audio, which was replaced by audiotapes. Audio CDs have the ability to enable users to skip to different places on the disc. CDs can be used unlimited time without losing quality, while audio tapes can lose the quality if you use it around ten times. Because in the CDs, the laser that reads data does not put the pressure on the disc, while in a tape, the play heads drape slowly wear away the magnetic strip on the tape.

What is the use of a CD on the computer?

CDs are used to store data, which can be executed in the future. Thus, you can load software programs in the compact disc that can be moved onto the computer. Even, Windows files are also stored in the CD, which can be installed onto the computer. Furthermore, the stored files on the compact disc can be transferred to other computers, through which you can make a backup of all files.

History of CD (Compact Disc)

The two companies Sony and Philips announced to developed the CD (Compact Disc) with developing prototypes separately in the late 1970s.

How it started

In 1957, Italian Antonio Rubbiani began the story of CD with experiments involving the rudimentary video disc, which motivated to all generation of scientists to work on the digital technology.

Later nearly 12 years, Philips began to develop the ALP (Audio Long Play) disc. It used the technology named laser that became a challenge for the traditional analogue vinyl records. The Audio Long Play was used for longer times, and it took space less than as compared to their vinyl counterparts.

The Philips team worked on multiple experiments with the digital disc technology in Eindhoven under the guidance of the technical director. Later, these experiments were unused.

However, Philips seriously worked and launched the Compact Disc Project in 1978. The purpose of this project was to replace both the Compact Cassette Tape and analogue video equipment for the new format. At that time, both technologies were more popular, which had been in use for many years.

In 1977, the project name for the Compact Disc Project was decided. It was chosen by Philips to make awareness of people for Compact Cassette's success. Then, Philips began to work hard for the work completed by its digital audio research department, which led to a very exciting juncture.

The commercial laserdisc player was already released into the market by Philips. Thus, in terms of the physical design of the compact disc, it was ahead as compared to its competitors. However, Philips was unable to get the benefit of digital audio recording for developing the CD ahead.

Additionally, Sony was also working to develop a compact disc, so it was the very opposite problem to contend with it. Also, it had much knowledge to develop and implement the better digital audio circuitry, but it was unaware of the process of making the physical Compact Disc.

In 1979, as a result of these developments, Sony and Philips gave a surprise to the world with the announcement (during a conference in Japan), they both will jointly develop the CD. Thus, both the companies began to work together for the next few years with the new deal.

Engineers (working at Philips), they focused on the physical design of the disc, and think about how the laser can read the information on the disk surface. Sony's specialists in digital technology worked on the analogue of digital conversion circuit design, concentrating on the design of the error correction code and the encoding of the digital signals.

How was developed the CD Red Book standard

Sony and Philips brought out the Red Book in the general acceptance of certain specifications about the CDs. Its name (Red book) was got from the color of the cover of the first publication.

The Red Book had specifications, which contained the sampling, recording details, size of the disc, and many other standards. Even some standards still remain unchanged.

Then, the Compact disc was made portable and smaller in size than a vinyl record. It had a diameter of 120mm and could be played in stereo systems. Furthermore, it could store a large amount of data as compared to the cassette or the vinyl record.

After that, Philips and Sony started work separately and tried to produce their own CD-drive equipment. Earlier a month on the 1st of October 1982, Sony released the first commercial CD drive. That was a remarkable event in CD development history. Sony introduced the CDP-101 Compact Disc Player in the market first in Japan and then Europe. Till the early part of 1983, it did not reach the shores of America.

In the year 1984, Sony released the first portable CD player by which again it beat Philips company for a second time. The time was coming to introduced commercial CDs in the market. The first commercial CD hit in the market by ABBA, the Swedish pop group.

The lesser-known Yellow Book standard

Once again, the second book of standards was more appropriate for both companies, in spite of still they were working separately. In 1983, the Yellow Book of standards released that was based on the Compact Disc-Recordable (CD-R).

In terms of electronics, the CD could be changed in a way that it would store data on the disc that could be read by a computer. This was a notable development in the CD's history, which made a far impact on the CDs developments.

The compact Disc would able to store a large amount of data in spite of their size, and it would be an ideal replacement for the exiting floppy disc. CDs would work more positively to access the data as they included a high speed. This standard was ready for commercial use by individuals and businesses in 1990.

In 1995, Sony had a plan in the pipeline that begins a step to standardize Digital Versatile Discs (DVDs), which was the next notable movement in CD history. DVDs were not developed to replace video cassettes and analogue video storage, and they can even be used to store data in place of CD-ROMs and CD-Rs on the computer.

However, DVD+Rs and DVD-Rs are still available in the market, as DVDs are not completely standardized even until today. The DVD+Rs and DVD-Rs are providing a little different functionality.

The future of the CD

In the future, CDs can be used for many uses. For example, it can be used to replacement for analogue vinyl records and cassettes. Also, it can be used to store, backup, and transfer computer data, and as proved by recent continue to remain popular for entertainment sales figures.

Different types of Compact disc (CD)

There are different types of Compact Disc, but they all are used to store digital information.

  1. CD-ROM
    The term ROM means read-only memory that allows the computer to read the data, which is already stored on the computer, and it cannot be deleted or changed. It was more popular for distributing games and software for several consoles. Furthermore, any standard can be used to play CD ROM recordings.
  2. Recordable CD (CD-R)
    The CD-R stands for recordable, which is also known as CD-WORM (Write Once, Read Many) or CW-WO (write-once). Philips and Sony jointly developed it. Usually, these types of CDs have 74 minutes of music storage available, but some CDs can store as much as 80 minutes of music. It includes an advantage that the information is written once and can be read multiple times. It also had a limitation that it was not properly compatible with all devices; therefore, it had no ability to read all devices.
    When it is inserted into the player, the inbuilt laser rays read the data, which is recorded by the user on it. The music CD became popular with the Recordable CD because most music albums were released in this format.
  3. CD+R
    The CD+R is not relevant with the CD-R, the R in CD stand for recordable. A group of companies developed the +R format. It was developed to increase the amount of storage available on a compact disc. The CD+R allows for around twice storage space as compared to standard CD-R.
  4. Rewriteable CD (CD-RW)
    The CD-RW can be used to write data a number of times, erased and re-used, and also used as a normal CD-R. Usually, a rewritable CD can store up to 700 MB of data and can be written again as many as 1000 times. But rewriting the stored video and audio in it reduces the quality of data. On a CD, a CD burner melts the recording layer onto a CD by using its highest laser power. In CD-RW, the burner melts the data layer by using its medium level of laser power; new data can be added to the disk. A CD player will not change the recorded layer, and it uses the lowest amount of laser power to read a CD.
  5. Video CD (VCD)
    Simply, it was a CD, including moving images and pictures. It had a capacity of 650MB/700MB and could store 74/80 minutes of data. It was mainly used for watching movies. Later it was replaced with the SVCD and DVD as an image's quality on this was not too good.
  6. Mini-CD
    The Mini CD is wide around 3 inches and can store 210 megabytes of data or a maximum of 24 minutes of music. Mini CD's can be used with most CD players.
    It was widely used for single song recordings but also used for advertising and business purposes.

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