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QUESTION:

Can you help clear up the difference between CD-ROM, CD-R and CD-RW? Also can you advise on which is better suited for what purpose.

ANSWER:

Most software today comes on CD-ROM. In fact, you'll be hard pressed to find software that's sold on floppy disk these days. One reason is that a CD-ROM holds around 650 megabytes as opposed to a 1.44 megabyte floppy and most applications well exceed 1.44 megabytes. The other reason CD-ROM has become the delivery media of choice is that every modern and even most older computers have a CD-ROM drive. Floppies have fallen out of favor because they hold so little and some computers like the iMac don't even have floppy drives anymore. Zip drives are popular but fall way short of being on every computer made today. So since the CD-ROM is the most prevalent, it's ideal if your need is to distribute programs, files and other data to any computer.

CD-R stands for recordable CD. Once something has been recorded to a CD-R disk, it cannot be erased. Earlier versions of CD-R would only let you record once to a disk. Any space not filled in that initial recording would be wasted since you could only write to it one time. Today's CD-R drives are multisession which means that you record a little at a time and as often as you want until the disk is filled. Most importantly, a CD-R disk can be read on any computer's CD-ROM drive. In addition, it can be played on any audio CD player if you record digital music to the disk. Not being able to alter data once it's recorded lends a degree of security to this format. Add to that its universal acceptance and you have CD-R's two biggest attributes. In addition, CD-R disks are very inexpensive (around a dollar a disk). The cost-per-megabyte of storage is only around a few pennies making CD-R an ideal candidate for the non corruptible archiving of computer data.

CD-RW stand for read, write (recordable, erasable) CD. Like CD-R, this technology lets you record to a CD but instead of being permanently inscribed, you have the ability to erase any data at any time and then re-record over and over again. CD-RW disks are more costly than CD-R disks but their ability to be reused helps offset the additional cost. CD-RW is a cost effective way to archive important data that may need changing at a future time. The downside to CD-RW disks is that they do not have the universal acceptance of a CD-R disk. Older CD-ROM drives that are slower than 32X (made approximately in or before 1998) probably won't be able to read CD-RW disks and audio CD players cannot read them either. So if your need is to distribute universally, CD-RW won't do it for now. Besides, why send someone a three dollar disk when you can send them one that only cost you a buck? Of course, as those slower CD-ROM drives in those older computers fall into obscurity with the passage of time, eventual universal CD-RW acceptance will become more of a reality. And their cost will come down as well.

One way to hedge your bet is to get a CD drive that can use all three formats. Plextor now has their new 3-in-1 PlexWriter 8/4/32 ($269) internal and 12/4/32 ($399) internal CD drives. Both drives can read CD-ROM, record and read CD-R and read and rewrite CD-RW disks. The numbers refer to the speed of the format. For example, the first model can record a CD-R disk at 8X speed, rewrite a CD-RW at 4X speed and read a CD-ROM at 32 X speed. The drives will work on a PC or Macintosh. The 8/4/32 hooks to your computer via an E-IDE or ATAPI interface, the 12/4/32 hooks to your computer via a SCSI interface. An external 12/4/32 SCSI model is available for $499.

Plextor Corporation (800) 886-3935 or (408) 980-1838 www.plextor.com