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P-CAV Writing At 40x?
By Aaron Yip
Category : Optical Storage
Published by TechToyer on Tuesday, 23rd April, 2002

Extra! Extra! Extra!

I didn't think much of it when Iomega told me that they'll be sending me a new firmware for their CDRW23040 INT-B (LITE-ON version) drive. But my jaw dropped when they told me this new firmware, version VZOS3, will literally change the whole architecture of the drive. Remember that the CDRW23040 INT-B writes at high-speed using Z-CLV technology? Well with this new firmware the drive will now write using P-CAV technology instead. On top of that, the firmware will also add the long-awaited Mount Rainier support to the drive.

Mount Rainier Support

Mount Rainier allows users to drag and drop files to and from a drive within Microsoft's Internet Explorer, save files directly to the drive from any application or download files directly from the Internet. Mount Rainier functionality would also be incorporated into the Linux operating system and Apple's MacOS operating system as well. All these without the need of 3rd-party software (Such as Nero's InCD or Adaptec's DirectCD).

Z-CLV & P-CAV Explained

With References From Yamaha's website

There are generally two writing methods to achieve reliable high speed writing (16x and above) while keeping disc rotation speeds at manageable levels. One is Yamaha's P-CAV (Partial Constant Angular Velocity), and the other being Sanyo's Z-CLV (Zone Constant Linear Velocity) which many of us are familiar with, since most CD-RW drives today features Z-CLV technology.

Click me!! Z-CLV when writing at 40x. (Click for clearer picture)

Z-CLV method utilizes the existing CLV method combined with linking technology developed for buffer underrun protection. The writing of a disc is divided into several zones, and writing speed is kept constant within each zone. When it shifts up to the next speed, writing is suspended and then restarted, linking the two zones together, using the buffer underrun protection.

Click me!! P-CAV when writing at 40x, using a SMARTBUY 40x media. (Click for clearer picture)

P-CAV method keeps disc rotation constant in the inner portion of the disc as writing speed smoothly accelerates outwards until it reaches top speed. After that, writing speed is kept constant (CLV) until the end of the writing.

Based on the yellow lines in the pictures above that represent the Drive Spindle Motor Revolutions, the rotation speed is kept moderated in the inner portion of the disc with the P-CAV method (compared to the Z-CLV method). This is essential to help keep the quality of writing in the inner portion of the disc, because by moderating the disc rotation it reduces the vibration that can corrupt quality. Also, since the rotation speeds are low it is generally accepted that the life of the laser diode and the drive's pickup will be extended as well.

Currently the only manufacturer to advocate the use of P-CAV technology in their drives is Yamaha with their 2200E and 3200E series of CD-RW drives. Not anymore it seems, as there is now a new P-CAV kid on the block. But how does it perform? To switch from Z-CLV to P-CAV is as simple as just flashing the firmware? Read on.

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