Fig.1 CD-ROMs
Along with the development of information technology, many families now have their own computers at home. New personal computers are usually equipped with CD-ROM drives for multimedia uses. You must have used CD-ROMs. But do you know the working principle of CD-ROM? What are its advantages over other storage devices?
The full name of CD-ROM is Compact Disc - Read Only Memory. It is a read only information storage device. Roughly speaking, a CD-ROM consists of three layers. It has a transparent substrate as its base. On the base there is a reflective metal layer which carries information. On top of it, there is a protective coating. We know that information like sound, graphics and computer software can be digitized, that is, the data can be represented by binary numbers, which are made up of a series of '1' and '0' digits. This information is recorded on the metal layer. If we magnify the surface of the metal layer, we can see 'pits' and 'lands' in circular tracks.
We use laser beam to read the data. When the beam travels from the direction of the base and reaches the pits, the pits on the metal layer reflects the beam like a mirror. The depth of the pits is one-forth of the wavelength of the laser. The laser rays reflected by the pits and the lands have a path difference of half the wavelength (Fig. 2). It leads to destructive interference, that is, the two rays cancel each other and no reflected ray is resulted, and this produces a '1' digit. The path difference is zero for two rays both reflected by the pits, or both by the lands. No destructive interference occurs and we say it is a '0' digit. Therefore we have digit '1' at the edge of pits and digit '0' elsewhere. This is the basic mechanism of information storage and retrieval using CD-ROMs.
Fig. 2 Destructive interference occurs when laser is reflected by the edge of a pit, giving a '1' signal.
As laser beam can be focused very sharply, we can make very narrow tracks, typically in the order of wavelength of the laser, so the storage size of a CD-ROM is much larger than that of a floppy disk. We can store a lot of data like a whole movie or many softwares in a single CD-ROM, thus it speeds up the development of multimedia computers. No mechanical contact is required to read the data from a CD-ROM and it has a protective layer on it. Therefore a CD-ROM is very durable, which is one of its greatest advantages.
At present, we use semiconductor lasers, whose wavelengths are in infrared region, for reading CD-ROMs. If we use violet or even ultraviolet lasers, the tracks on CD-ROMs can be ten-folds narrower. Correspondingly, the capacity can be increased a lot. However, these products are not fully developed yet.
MP3- audio MP4- audio and video MP5- audio, video
what is Audio-Visual round
The compact disc or CD was introduced in the year 1982. It was originally developed for storing digital audio and digital data.It all started in the year 1979, when Philips and Sony got together to design a new digital audio disc. The team leaders of this project were Kees Immink and Toshitada Doi. Philps handled the maunfacturing process along with the Eight-to-Fourteen Modulation (EFM), while Sony too care of the error connection method, better known as CIRC. However, Philips claim that this invention was not a one man's job but a collective contribution by members of both the companies who worked together as a team.It was considered as a "Big Bang", in the digital audio world. This disc was taken over by nearly all markets across the globe, especially the Europe and the United States consumer market. The first successful CD to be launched was Brothers in Arms in 1985.A compact disk (CD) is a popular form of digital storage media used for computer files, pictures, and music. The plastic platter is read and written to by a laser in a CD drive. It comes in several varieties including CD-ROM, CD-R, and CD-RW.James Russell invented the compact disk in 1965. James Russell was granted a total of 22 patents for various elements of his compact disk system. However, the compact disk did not become popular until it was mass manufactured by Philips in 1980.The first working prototype was produced in 1979, and CD players were released in 1982Sony introduced the world's first CD player, the CDP-101 on October 1st, 1982. It hit the market with a retail price of about $900 and featured the now familiar slide out tray loading mechanism for the first time.Variations of the optical disk and compact disc started to appear in the late 1970s. The ones we are used to were launched in 1982.http://wiki.answers.com/When_was_the_CD_and_CD_player_invented&action=editThe first CD or compact disc was invented in the year of 1982.19821982 or 1983The first CD or compact disc was invented in the year of 1982.
No, it can output any type of audio.
Vesa is a synonym of the Video Electronics Standards Association. The vesa committee has designed the VESA BIOS EXTENSION (VBE). The VBE include some basic core functions of the software interface for the display and audio devices. On most graphic cards are a vesa-bios.
an audio text
An audio CD is a compact disc containing audio data according to the Red Book standard.
my PC audio is not working
an audio text
(Apex) An audio text.
Audio MiniDisc usually. As opposed to Audio CD (compact disc) or even DataMD (Minidiscs which record data, or audio AS data, such as in multi-track systems.)
There are no graphics to display on an Audio CD
A flash audio recorder works by recording audio onto a compact flash card. The amount of audio you can record depends on the size of the memory on the flash card.
Assuming that by "compact" you mean a CD, then yes, most DVD players will also play audio CDs.
About 700Mb OR the equivelant of about 80 minutes of CD-Audio.
Digital audio can be stored many different types of digital device: • Computer. • MP3 player. • Compact Disc. • DVD.
Two.