English Compact Disc

The Unit of CD-ROM must be considered obligatory in any computer that is constructed at the moment, because the majority of software is distributed in CD-ROM. At the moment, although still they are used, they are beginning to fall in disuse since they began to be replaced by DVD units. This mainly must to the majors intelligence-gathering capabilitieses, since a DVD-ROM exceeds in capacity to a CD-ROM. But that is the CD and the DVD? A CD-ROM (abbreviations of the English Compact Disc – Read Only Memory, " Compact disc – Memory of Only Lectura"), it is a compact disc used to store nonvolatile information. The CD is a flat plastic disc with codified digital information in a spiral from the center to the outer edge. A standard CD can lodge 650 or 700 MB of data. The CD is popular for the distribution of software, especially applications multimedia, and great data bases weighing only 30 grams.

A DVD however is divided in two categories: those of simple layer and those of double castrate. The Virgin DVD of simple layer can keep up to 4,7 gigabytes, around twelve times more than a standard CD. The DVD uses a method of more efficient codification in the physical layer: the systems of detection and correction of errors used in the CD, like the cyclical redundancy check CRC. However the users of computers will want to keep their own Virgin information and there he is where Virgin CD and DVD are born. And they carry out by means of the corresponding recorders or burners, or CD or DVD. A cd player is an electronics that allows to the reading of these discs by means of the use of a beam of a ray laser and the later transformation of these in impulses electrical that the computer interprets. These discs are written by engravers of CD on CD R (virgin CD) with the difference that makes in opposition to the reader, that is to say, transform electrical impulses into a light beam laser which they store in the CD binary data in the form of level wells and.