Burning ROM: Writable CDs Find Lots of Uses
Although they've been around since the 1980s, CD drives are finally finding a place on modern PCs as a recording tool instead of their more traditional role as a read-only device for software installation or access to pre-recorded files, archives, images, and so forth. In large part, this stems from the decreasing cost of read-write instead of read-only CD drives. At around $100 for an acceptable device, it's become quite cheap to include read-write drives in standard PCs. In fact, read-write drives have now become the rule rather than the exception. Given that your current or next PC is likely to have a read-write CD drive, what can you do with this relatively new but standard tool on your machine? We think you'll be pleasantly surprised by the number of answers you'll find here and in the other resources we provide in this article.
Read-Write CD Basics
Most Compact Disc, or CD, media is write-once media. When you buy a pre-recorded CD it's already been written. If you buy a blank write-once CD, it's called a CD-R (for recordable CD). Today, these blanks typically cost less than a dollar each (sometimes, much less). But there's another kind of recordable CD called a read-write CD (abbreviated as CD-RW) to which you can write more than once. Media manufacturers sometimes disagree on how many times you can write to a CD-RW without starting to damage the medium, but most experts agree that it's safe to re-record such a disc anywhere from 10 to 100 times without fear of losing data in the process. Please also note that CD-RW media costs more than CD-R media (as you'd expect from something reusable); typical prices for a single CD-RW disk are somewhere between one and two dollars, but can also be as much as 30 percent less.
When you buy a read-write CD drive nowadays, you'll see it rated with three numbers, as in 16-10-40. Here's how to decode what this information really means:
First number (16). Describes the speed at which the drive can write CD-R media.
Second number (10). Describes the speed at which the drive can write CD-RW media.
Third number. Describes the speed at which the drive can read an already-recorded CD.
All three of these numbers are multiples of the original speed rating for early CD players, often denoted 1x. This is why you'll see some CD-RW drives rated as 16x10x40x; the numbers rate the drive's various speeds relative to the original 1x speed. 1x translates into multiples of 150 KBps for data CDs written in CD-ROM format, or into 172.27 KBps for audio CDs written in CD-DA (digital audio) format.
The reason that two different speed ratings apply to recording CD-R and CD-RW media is because it takes longer to position the laser beam that "writes" information to a CD-RW disc than to a CD-R disc. Thus, the recording process is slower for CD-RW media than it is for CD-R media. A speed rating of 16-10-40 is typical for the kind of mid-range read-write CD drives that you're likely to find bundled in a new PC. Today, all but the most expensive such devices seldom have ratings higher than 40-12-48. Anything at or between these ratings is quite acceptable for typical home or personal use.
Given a choice between CD-R and CD-RW media, why buy CD-Rs? We'll touch indirectly on more reasons soon, but for now suffice it to say that there are plenty of applicationssuch as recording data archives, backups, or music CDswhere writing only once to the medium is exactly what's needed, or is sufficient to do the job correctly. Don't forget, too, that CD-RWs cost more and take longer to write than CD-Rs. Thus, the CD-Rs remain popular even as prices for CD-RWs continue to decline.
For a nice glossary of recordable CD terms and concepts, check out the "CD Recordable Glossary." You'll also find Andy McFadden's CD-Recordable FAQ an invaluable and nearly inexhaustible source of additional information on the subject.