Roxio's Complete Guide to Buying a CD-R/RW Drive

posted: February, 23 2003

By Jeff Sauer

Now that you've got the best CD-burning software in the world, maybe it's time to upgrade your CD recorder. Recording technology has been advancing rapidly, especially on the DVD front, and speeds have also increased dramatically in the last couple years. If you're poking along at 2X or 4X write speeds, or just want to understand the latest trends, this article is for you!

Deciphering the Alphabet Soup

The first thing to decide is what type of drive you need: CD-R/RW or some combination of CD and DVD reading/recording. While most users understand that CD-R refers to CD-Recordable and CD-RW means CD-ReWritable, not everyone realizes that the two formats use different types of media and laser configurations. Most burners today support both. Some newer drives add DVD read support (typically called "combo" drives), or DVD recording support (often called "super" drives). These drives carry a cost premium, but are great if you only have room for one optical drive in your system. If you have room for two drives, a fast CD/DVD reader makes a good combination with a CD and/or DVD recorder, since you can then copy directly from one drive to the other, instead of having to rip data to hard disk first.

If you want DVD recording capability, you'll also have to choose from three competing rewritable formats: DVD-RW, DVD-RAM and DVD+RW. DVD-RW generally offers better backward compatibility to CD-R and CD-RW, with DVD+RW a close second. While DVD-RAM was the first entry in the format wars, it has largely been outshadowed by the other two.

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By the Numbers

How much speed do you need in a CD recorder? Today's fastest CD-R drives can reach transfer speeds as high as 48X. (1X for CDs is 150KB/sec). However, you'll usually see at least two numbers in drive marketing material separating write and read speeds (for example, 24X/48X). CD-RW drive specs add a third speed for rewriting in the middle (for example, 24X/16X/48X). As you can see, write speeds are typically much lower than read speeds, but that's okay, since most people spend relatively little time writing as opposed to reading.

If you get a drive with DVD read and/or writing capability, there will also be numbers for DVD speeds, which are measured differently from CDs. In the DVD world, 1X means 1.38MB/sec, which means a full 4.7GB DVD can be read or written in about an hour. The current state of the art for consumer DVD recorders is about 8X for reading and 4X for writing.

Unfortunately, while specs can be helpful guideposts when comparing one drive to another, they can't be taken strictly at face value. Unlike hard drives, CD drives spin at different rates depending on what section of the disc the laser is accessing. Therefore, the specs denote a drive's fastest possible speed, typically when reading from or writing to the outer sectors of a disc. Real-world transfer rates can be one or two notches below the spec. Drive performance can also be limited by your system. For example, the speed of your USB or IDE connection.

nternal or External?

If you have an open drive bay in your computer, you'll save a little money and desk space with an internal device. However, this means opening your PC and understanding internal cabling. External drives are a little more expensive, but offer the flexibility to move around to different PCs. You may also want to consider a "portable" drive, which is powered by the USB or FireWire bus in your computer, rather than plugged into a wall.

Interface Options

If you choose an internal drive, the two interface options are SCSI and ATAPI/ATA/IDE. In newer machines, these interfaces handily exceed maximum transfer speeds for both CD and DVD drives, so whichever you happen to have in your computer is fine. However, older versions of SCSI and ATAPI (especially if DMA is not supported) are potentially too slow to support maximum CD-R/RW data transfer rates. If you have an old machine, consider an external drive that you can transfer to a newer machine when you upgrade.

For external drives, the choices are more complex. You can get SCSI, FireWire (also known as IEEE1394 or i.Link), and USB 1.0 or 2.0. Again, SCSI and FireWire are fast enough for any CD recorder, but USB 1.0 will greatly limit your recording speed. While USB 2.0 theoretically supports up to 60MB/sec., it is new and hard to find. FireWire and USB drives both have the major advantage over SCSI of being hot-pluggable, so you don't have to turn your computer off before attaching them. For now, the best choice in external recording is FireWire. USB 2.0 should catch up as it becomes more widely available.

Buffer Underrun Protection Technologies

Finally, make sure you get a drive with buffer underrun protection, which safeguards against the dreaded "coaster," or CD ruined during the writing process. A CD-R's laser writes data in a continuous stream until it either closes a session or a disc; this requires a continuous flow of data from the host computer or storage device. If there is an interruption to the flow of data, the laser effectively writes garbage and causes an error. If that occurs, the disc is likely to be unusable.

The first line of defense against interruptions in the data stream is an on-board memory buffer. All CD-R/RW drives leverage this buffer to offset the inevitable minor hiccups in the data flow coming from a computer. Obviously, the larger the buffer, the more protection it provides against running out of data (called a "buffer underrun"). More memory adds cost, but if prices are equal, more memory is better. The best CD-RW drives today typically offer 4MB-8MB buffers.

Buffer underruns were very common in the early days of CD-R technology when computers, buses, and data transfer protocols were much slower. Computers are better, on-board buffers are bigger, and buffer underruns far less common, but today's high recording rates continue to push the limits. Fortunately, device makers have developed a number of other solutions to combat the problem.

Some of the buffer underrun protection schemes out there include BURNProof, Safeburn, JustLink, Seamless Link, ExacLink, Shock Proof, and Power-Burn. They all work on the premise of stopping the laser from burning if the buffer runs out of data, before it causes a buffer underrun. Once data is flowing again, each technology matches the laser's position to where it stopped and restarts the burning process. You should make sure your drive has some form of buffer underrun protection, plus as large a memory buffer as possible.

The Bottom Line

That's everything you need to know to make an informed CD-RW buying decision! Start with the type of drive and speed you need, then narrow things down by interface and internal or external, and finally, look at the bells and whistles, like buffer size, and buffer underrun protection technology. Other things to consider include bundled software utilities, connections for headphones and sound output, fan noise (if any), warranty, casing, and manufacturer reputation.