Optical Drives – CD and DVD

There are many ways to store computer data.  Most of the data is kept on hard drives which are permanently installed in the computer case.  Data can also be stored on removable media such as floppy disks, memory sticks, CDs and DVDs.

This removable media is ideal when you need to take data with you, for example when you need to bring work home with you from the office.  It is also useful for archiving old data.

Floppy disks used to be the most common type of removable media.  Even though they are still included on many modern computer systems, their usefulness is limited because of the small amount of data they can store.  The removable data of choice these days is either CDs or DVDs.

Types of Drives

CDs and DVDs are called optical media because a laser is used to read and write data.  Optical drives come in many flavors.  Some of the configurations are -- CD-ROM, CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, and DVD+RW.  There is also a format called DVD-RAM – this is a rewritable format which has similarities to hard drives.  There are not many DVD burners that support this format and it is mostly used for digital camcorders.

What do all of these acronyms mean?

CD refers to Compact Disc, and DVD means Digital Versatile Disc.  ROM means Read Only Memory -- you cannot write data to a CD-ROM.  CD-R means Compact Disc Recordable, a type of disk that can be recorded only once.  In contrast to CD-R, CD-RW (Compact Disc Rewritable) can be recorded and erased many times.

DVDs also are available in R and RW formats.  The original DVD specification was DVD-R or DVD-RW.  A more recent type of DVD is the 'plus' format (DVD+R and DVD+RW).  The two DVD formats are only partially compatible but many hybrid drives have been developed that can use both types.  You will see these marked as DVD±RW.

When buying an optical drive for your computer, your main consideration will be whether you wish to be able to record your own CDs or DVDs.  If you have no need for recording you can probably get by with a basic CD-ROM or DVD drive.  However, if you wish to make your own disks for recording music, movies, or data you need either a CD or DVD recorder.

DVD recorders are backwards compatible so you can record and play CDs on them as well as DVDs.  CD recorders cannot handle DVDs either for reading or writing.

Speed

The speed of CD and DVD drives is shown as a multiplication such as 12X or 50X.  These numbers refer to the data transfer rate and use the original CD and DVD specs as reference points.  DVD has a much faster transfer rate (1350 kb per second as compared with 150 kb per second for CDs) so a DVD player rated at 8X is actually equal to a CD player rated at 72X.

CD recorders are very common these days and prices are almost as low as CD-ROMs.  Whereas a CD-ROM costs about $15, CD recorders start at about $20.  This minimal extra cost gives you the convenience of an extra storage medium.

DVD players are a bit more expensive, starting at about $50 or so.  DVD recorders are available at an extra $20 or $30 premium.  DVD recorders may not be so useful to the average computer user but people who make their own movies or have a lot of data to store may find them to be a necessary part of their computer setup.