Good data backup means taking your data offsite. Most people think tape drives when this subject comes up, but Iomega wants you to think "removable hard drive" and created this market almost 25 years ago.

Those readers with gray hair may remember the Bernoulli Box, an external hard drive that used eight-inch cartridges to hold a whopping 5M bytes of data. Snicker if you want, but 5M bytes ruled when most PCs still used a floppy drive containing 360K bytes (that's .3M bytes).

After Bernoulli, Iomega released its hugely successful Zip drive line. Starting with 100M bytes, a Zip drive was the same size as a regular floppy disk drive, but the disk held 100M bytes rather than the newly upgraded 1.44M-byte floppy drive of the day. Three years later, the capacity jumped to 250M bytes per same size disk and then up to 750M bytes. Don't think Zip drives are just super-capacity floppies; they are real hard disk platters in a removable case.

The spotlight wandered away from Zip drives as CDs became writeable (700M bytes) and cheap. Then DVDs became writeable at 4.5G bytes and we thought portable data salvation was ours. But storage needs increase constantly, and DVDs never give the performance of hard drives, especially when writing.

Now Iomega's upped the removable storage ante again as REV drives start winding their way through a multitude of vertical markets. Smaller than a floppy drive, but just a bit thicker than two floppies, the REV cartridges hold 35G bytes natively. When coupled with back-up software using compression, the capacity jumps as high as 90G bytes, although 70G bytes seems to be the average. But that's far above even the expensive dual-layer, blue-laser type of DVDs coming out now.

Two clever ideas will propel the REV drive to more success than the Zip or Bernoulli. First, the components (platters and heads inside the small case) come from standard 2.5-inch hard drive parts. Iomega had to create new products earlier on, and there were no component makers for Bernoulli and Zip drives outside Iomega. REV drives, however, benefit from the mass market for drives commonly used in notebook computers and all types of consumer hard drive appliances. When component prices drop, Iomega wins. As component improvements drive capacity increases, Iomega wins again as the same size REV cartridge starts holding more data.