CD-ROM+(compact+disc+ready-only+memory)+DVD+readers+and+burners

=Strand 3: IT Systems=

CD-ROM (compact disc ready-only memory) DVD readers and burners
Today, **CD-R** and **CD-RW** media are commonly used to make back up copies of data in order to exchange information between computer systems. Due to technological advancements basic **CD-R/CD-RW** drives have been replaced by **combo drives**. i.e. //they read DVD and CD-R/CD-RW media//.

**DVD** originally stood for **digital video disc**, because the discs were designed to replace the old **VHS tapes(Video Home System)** in video stores. Now, people say it stands for **digital versatile disc** due to its high capacity. Physically, DVD and CD are of the same size(diameter of 120mm) but a DVD can hold information between **4.7GB** and **17GB**.



A **single layer DVD** can hold up to **4.7GB** of information but a **second layer doubles** the data capacity of the disc. Most commercial DVD movies are **encoded on dual-layer DVD’s**. **DVD-ROM** drives can play **DVD movies, read DVD** data discs, **read standard CD-ROM’s**, and **play audio CD’s**. Most computers have them today and vastly utilized in home DVD players. A combination of **DVD/CD-RW** drive offers the advantages of a **DVD-R drive** and a **CD-RW** drive //in a single unit that can play DVD movies and audio CD’s, record and erase data on CD-RW disks, burn audio CD’s and CD-ROM’s//. This type of drives //can not burn DVD’s but, they can burn CD-R and CD-RW media//. Fortunately, DVD-RW drives **are not that expensive**. These types of drives can be used to burn data on CD’s and DVD’s. Early DVD burners were rated with **speeds of 1X** //– it might take as long to record as it does to watch it.// Today, //drive speeds are measured in multiples of 1X.// e.g. a 16X drive might record data 16 times faster than a 1X drive. **N.B.** //Speeds can be affected by the type of media, the type of connection to the computer, and the computers software//.

DVD drives are gradually being //eradicated// by **Blu-ray drives** that can read and write on media that holds up to **5OGB of data on two layers**. **BD-RW drives** //can read and record on all types of media available//. In few years time, BD drives //are likely// to be **the standard drives** in most PC’s.



Below is a chart which summarizes the capabilities of different types of drives;


 * || ** CD-ROM **
 * (read-only CD) ** || ** CD-RW ** || ** DVD-ROM **
 * (read-only DVD) ** || ** DVD/RW ** || ** BD/ROM **
 * (read-only Blu-ray) ** || ** BD/RW ** ||
 * ** Capacity ** || ** 700MB ** || ** 700MB ** || ** 4.7GB(single-layer disc),9.4GB(dual-layer disc) ** || ** 4.7GB(single-layer disc),9.4GB(dual-layer disc) ** || ** 27GB(single-layer disc),50GB(dual-layer disc) ** || ** 27GB(single-layer disc),50GB(dual-layer disc) ** ||
 * ** Play audio CD ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** ||
 * ** Play DVD movie ** ||  ||   || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** ||
 * ** Play HD Blu-ray movie ** ||  ||   ||   ||   || ** ☺ ** || ** ☺ ** ||
 * ** Read CD-R, CD-RW ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** ||
 * ** Write CD-R, CD-RW ** ||  || ** ☺ ** ||   || ** ☺ ** ||   || ** ☺ ** ||
 * ** Read data on DVD’s ** ||  ||   || ** ☺ ** || ** ☺ ** || ** ☺ ** || ** ☺ ** ||
 * ** Write data on DVD’s ** ||  ||   ||   || ** ☺ ** ||   || ** ☺ ** ||
 * ** Read data on Blu-ray disc ** ||  ||   ||   ||   || ** ☺ ** || ** ☺ ** ||
 * ** Write data on Blu-ray disc ** ||  ||   ||   ||   ||   || ** ☺ ** ||
 * ** Record DVD video ** ||  ||   ||   || ** ☺ ** ||   || ** ☺ ** ||
 * ** Record HD video ** ||  ||   ||   ||   ||   || ** ☺ ** ||