Roots and Guts: THE BASIC CD
By the late ‘70s, Philips owned an early claim to laser-based media thanks to its laserdisc players. Sony led the field in digital recording research. It was clear to those in the know that the future would be digital and optical. Keep in mind that Sony was still in a pitched battle against JVC for the supremacy of Betamax videotape over VHS—Sony lost, of course—and it’s easier to see why Sony elected to join hands with Philips in 1979 and create the Compact Disc-Digital Audio (CD-DA) standard rather than risk another format war.
This original standard is also known as “Red Book” because the report in which the standard was first published sported a red cover. The CD-DA spec was the foundation for much of the optical PC and home electronics technologies that would follow. Not least among these was the 120mm diameter and 1.2mm thick physical specification that shows every sign of staying with us for the foreseeable future. The apocryphal story behind the 120mm size is that given the laser technology of the day, 120mm was the right size to contain all of Beethoven’s roughly 70-minute Ninth Symphony.
The leap that made CD technology accessible to computers was the follow-up Yellow Book standard. Whereas Red Book only specified audio data, Yellow Book updated the decoding circuitry to recognize up to 650MB of computer data and became the basis of CD-ROM technology.
More specifically, the spec calls for 74 minutes of data, and each second contains 75 blocks comprised of 2,048-byte chunks. Do the math and that works out to 682 MB or 650 MiB. (A megabyte is 1 million bytes whereas a mebibyte is 1,048,576 bytes, but we’ll follow convention and just use the blanket “MB” description.)
Interestingly, the CD spec has a little wiggle room in it. As you probably know, the CD is built a bit like an old vinyl LP, with one long spiral track starting at the center and finishing at the outer edge. Within the track are “pits,” or bumps within the track, and “lands,” or level spaces between the pits, that the system interprets as values of 0 or 1. The distance between track spirals in a standard CD is 1.6 microns.
In an 80-minute (700 MB) CD, the track distance is shrunk to 1.48 micron. This buys the disc almost 1,700 more revolutions and accounts for the extra 50MB of capacity. Note, though, that cheap drives sometimes have trouble with this increased capacity media.

CD-R/W
Sony and Philips struck again in 1989 with the announcement of the Orange Book spec. There were ultimately three parts to Orange Book, and the first, magneto optical, largely flopped in the market, but MO does remain a niche product in vertical markets where extremely long media shelf lives are critical. The second part, CD-R, arrived in 1989, but the multi-write CD-RW spec didn’t appear until 1996.
Orange Book’s chief contribution was the introduction of multisession recording. Before this, you only got one shot at writing to a disc. If it worked, great; if not, it was a coaster. Most multisession recording is done through a process called packet writing. Packet writing fixes a high overhead problem found with other multisession approaches. For example, the conventional lead-in (beginning) and lead-out (end) data for an initial session consume about 50MB of space on the disc. The Universal Disc Format (UDF) technology used in modern packet writing uses only a slim fraction of this overhead for session management. While most operating systems don’t natively support UDF, it is easily added through burning software such as Ahead’s Nero Burning ROM or Roxio’s DirectCD.

The latest major advance in CD (and DVD+RW) writing was the Mount Rainier, or EasyWrite, spec. This built in greater defect management to the re-writing process and in so doing at last made CD-RW a dependable, viable replacement option for older removable media, such as floppies and Zip disks. Mount Rainier also supports background “quick” formatting, so users can start using blank RW media almost immediately and not slog through a 20-minute wait. Not least of all, the spec uses significantly smaller sector addressing, meaning far less wasted space on a disc.
Mount Rainier didn’t debut until mid-2002 and gain widespread popularity until 2003, so you should check any older stock for compatibility. (The technology must be supported by the hardware.) This also offers a good upgrade opportunity to clients with frequently used drives that predate Rainier.

Write-once CD-R drives gave way long ago to rerecordable CD-RW units. Throughout the age of burners in the ‘90s, buffer underruns were a huge problem. This was a situation wherein the drive’s buffer emptied as system resources were busy with other tasks besides feeding the drive more data. When the buffer reached 0%, the recording session ended prematurely and the user was left with a coaster. Sanyo was the first to fix this problem a couple of years back with a terribly obvious solution: When the buffer gets low, turn the laser off and wait for the buffer to fill up again. When it does, resume burning. Both the drive and burning software must support this, and there are half a dozen different names for underrun protection depending on which brand you’re using. But again, this represents a great upgrade opportunity. Not only does buffer underrun protection help eliminate wasted discs and save time spent on reburning a session, it also allows the user to multitask at will without worrying over system resources.

This brings up one small point. Before underrun protection, manufacturers put large buffers on their high-end drives. With underrun protection, though, the need for large buffers vanishes. Even a 1MB buffer would do. So why do some drives still feature large buffers? Because for the fastest burning times, you don’t want the session to ever stop recording. In real life, the difference between a 2MB and 8MB buffer in a light multitasking environment will be negligible. However, if you have a customer with heavy multitasking needs who values burning speed, an 8MB buffer may be a notable value-add feature.

Recordable DVD
We could delve into the differences between the DVD+R/W and -R/W formats here, but there’s really no reason to do so. By now, you know that there has been a format war between the two types. Pioneer led off the battle with its support for -R/W, but even Pioneer is quickly shifting to making its DVD writers multiformat-compatible, meaning able to read and write in both formats. The best option for buyers is to get a multiformat drive, but they do cost more than single format drives. If customers pressure you for a recommendation between one or the other—and the differences these days are increasingly slight—the market trend seems to be toward +R/W. Microsoft embraced this format first, and most cutting edge DVD development seems to be happening in the “+” space, such as Philips’s recent announcement of demonstrating the first 16X DVD+RW mechanism in the laboratory. It may also be significant that the +RW format is MPEG-2 compatible while -RW is not...yet.
There is a third format, DVD-RAM, that actually predates the - and + formats. DVD-RAM got off to a shaky start because the original version of the technology, released in 1998, used 2.6GB cartridge-based discs, although this was updated to 4.7GB per side the following year, and now DVD-RAM is largely free from the cartridge constraint. The format’s competitive advantage is that whereas DVD±RW writes data in a linear fashion from the start to end of the spiral before starting over, DVD-RAM is designed for true random access writing, just like a hard drive. (We should note that current DVD+RW drives now support random writes.) “DVD-RAM has some additional benefits in terms of editing and error correction,” says Bennett Norell, director of marketing for the Information Systems Products Division at LG Electronics USA. “There’s simultaneous read and write for -RAM where it’s continuously checking what it’s written to make sure that it’s good, and if it’s no good then it rewrites it immediately. With + or -, if there’s an error on the disc you don’t find out until you’re finished writing the disc and you go try to use it, only to discover that it’s a coaster.”

The biggest drawback to DVD-RAM, aside from its higher price caused by lower production volumes, is its more limited compatibility. DVD-RAM drives will not recognize +RW media, although newer “DVD-Multi” drives will accept both DVD-RAM and DVD-RW discs. More importantly, most DVD-ROM and DVD-Video drives cannot read -RAM media. However, newer -RAM drives can write to DVD-R discs, which usually are more universally compatible.
Somewhat ironically, DVD-RAM’s random write capabilities make it a niche favorite in the video community because it is the only optical format that allows for scene splicing and insertion of one scene between two others. This is why you see home video recorders and digital camcorders opting for the -RAM format (including the smaller 80mm disc type for camcorders) over its competitors. The format allows for simultaneous recording and playback, making it an excellent choice for PVR applications. Additionally, DVD-RAM media specs out at 100,000 rewrites whereas -RW offers a mere 1,000. Because of its superior error checking capabilities and quicker market debut, many people standardized on DVD-RAM in the early days of the three-way format war and continue to use it as a high-quality backup and nearline storage solution. In fact, DVD-RAM remains very popular in Asia. The format poses an excellent opportunity to resellers and VARs who can sell the format (now at up to 3X speeds) for its competitive strengths and diversify themselves from the hordes selling ±RW drives.
“A lot of businesses have relied on -RAM for their backup solution for a number of years,” says Norell. “We have products that either let them continue using dedicated
-RAM or a bridge product that will let them continue reading their -RAM discs while writing to the new + and - formats. But the software that comes with these drives is pretty basic, so it’s really up to the VAR to provide a solution that fits the correct applications for their customer’s requirements.”

A Note on Speeds
The original CD-ROM drives featured a transfer rate of 153.6 KBps, or 150 KiBps (kibibytes), and the notation of 150 KBps became known as a 1X speed. 2X was 300 KBps, 4X was 600 KBps, and so on all the way up to today’s 8.6 MBps for 56X. In reality, what the CD spec originally called for was a 1.3 meters per second spin rate regardless of where the laser was positioned under the disc. The drive would simply change speed based on position within the disc in order to maintain that set rotation rate. This was known as a constant linear velocity (CLV). Increasing CLV speeds worked fine up until about 12X when speeds would approach nearly 6,000 RPM and motors were no longer able to adjust speeds quickly enough when jumping between disc areas.

At that point, drives moved to a constant angular velocity (CAV) approach wherein the rotation rate stayed constant. This is significant because far less track passes over the laser near the disc’s center than at the outer edge when rotation speed stays unchanged. The rated speed of the drive, though, is given only for the outermost track spirals. This is why we show average speed from across the disc as well as final speed at the outer spirals in our test scores. Keep in mind, too, that more poorly constructed drives are prone to vibrate at high rotation speeds, and to keep the vibration under control they will automatically drop the RPM rate.
This is why it’s important to perform testing in-house on several units of any given drive model you’re considering making standard equipment in your system sales. Regardless of what the vendor states should be the drive’s speed, the reality is bound to be less—significantly less if the drive model is prone to vibration correction. Very few resellers bother to perform such testing, and if you have test data to show your customers, this will serve as another differentiator and indicator that your operation takes extra care to ensure top component quality.
For DVD drives, the original 1X spec dictated a speed of 3.49 meters per second, or 1.385 MBps, which is why you always see DVD and CD speeds broken out separately on multiple format drives. The two cannot be easily correlated against one another. As with CD drives, DVD mechanisms soon changed from a CLV to a CAV approach, and thus performance testing is equally important for DVDs. Also note that you can save customers money and shave a bit from the system cost by cautioning them that faster DVD drives will have no impact on video playback performance. Either a drive can accommodate MPEG-2 extraction rates or it can’t (and all of them can). Speedy spin rates only benefit data reading and project write times.The Drives
Our product roundup here is meant to be illustrative rather than exhaustive. As you’ll see in our test results, there can be a considerable difference between what ends up on paper and what exists in the real world. For example, the interface burst rates reported by Nero CD speed clearly had no bearing on final read or write times. We used similar tests in Nero and DVDINFOPro in an attempt to verify results but only ended up more confused at certain points. For example, only one CD burner delivered accurate speed scores for outer spiral track reads, and the incompatibility with Plextor’s 708UF drive left us skeptical of the benchmark’s overall quality.
One should also note the rewrite times obtained in both the CD and DVD categories. In both instances, we used commonly available media: 10X and 2.4X respectively, although 4X DVD+RW is starting to gain popularity in the market. As you can see, real life performance is obviously bound by the capabilities of the recording media. As of this writing, the most common media on the market are 4X CD-RW discs and 2.4X DVD+RW or 2X DVD-RW. Finding 16X CD-RW media, as from Yamaha, or 4X DVD+RW media can be a real chore for purchasers of higher speed drives. This presents another value-add opportunity for your shop. As the latest drives emerge sporting faster speeds, it often takes weeks or months for appropriately matched media to hit mass market store shelves. If you can find such discs and keep them stocked for sale with your drives or systems, the extra margin won’t get you far toward retirement, but it won’t hurt and will once again demonstrate to customers that you’ve got your eye on high-quality solutions, not faceless, generic hardware sales.

CD Burners
One thing we found while researching this roundup is that external CD burners are becoming ever scarcer. We have a 40X Yamaha FireWire drive in the office that has served faithfully for some time, but such drives are on a swiftly declining curve as high-performance 52X internal units are now available for under $50 on the street, and even DVD-ROM/CD-RW drives aren’t much more than that. In short, when internal burners are cheap enough to be found in every PC, the need for external drives evaporates.

AOpen leads off the pack with two models, a 48X combo drive and a 52X dedicated CD burner. The COM8424 is a good, middle-of-the-road unit that we were pleased to see deliver a top read speed in excess of its 48X rating. Also noteworthy is that the drive turned in the best rewrite time of any unit we saw. AOpen sweetens the dish a little more by kicking in copies of Ahead’s Nero Express and CyberLink’s PowerDVD XP 4.0 and thus adds more value than the usual low-end white box offering.
AOpen’s CRW5232 was an odder bird. Out of the box, the drive performs as a 40X unit. You need to hold down the eject button for five seconds in order to enable the 52X mode. (The drive will revert to 40X upon a reboot.) AOpen claims that this is done to keep the drive whisper quiet by default, and, sure enough, the little beast puts up quite a rumble in 52X mode. Moreover, the drive’s CPU utilization was higher than we expected, although CPU usage is an increasingly academic point in this age of 3 GHz chips. We expect the real story is that in order to hit the drive’s $40 street price, AOpen had to cut a few corners in vibration and noise dampening. From a mass market perspective, this is probably a smart move as most consumers aren’t likely to notice the performance difference and resellers are still able to advertise a 52X drive. Better still, AOpen throws in silver and black face plates to replace the beige plate that ships on the drive.