High-capacity removable media drives are an ever-shrinking category. With competition at the low end (1GB and under capacities) from USB flash memory keychain drives and at higher capacities from external mini-hard disks (4GB and up), rewritable DVD (8.5GB), and larger USB and FireWire hard disks (20GB and up), there are only two current product families, both from Iomega:

• Zip. Flexible media, with capacities of 100MB, 250MB, and 750MB

• REV. Rigid media, with capacity of 35GB (native) up to 90GB (2.6:1 compression)

Other removable-media drives manufactured in the last few years have been discontinued. These include

• Iomega PocketZip (originally Clik!)

• Imation LS-120 SuperDisk

• Imation LS-240 SuperDisk

• SyQuest (SparQ, SyJet, and all other models)

• Iomega Jaz

• Castlewood Orb

• Iomega Peerless

If you use any of the drives in the discontinued list, you should consider moving your data to current magnetic, tape, or optical storage technologies. A discontinued removable-storage drive is essentially an orphan. There are three reasons for this:

• Repairs can be difficult to come by, especially in the case of a product such as the Castlewood Orb, whose manufacturer (Castlewood Systems) went bankrupt in 2004 and no longer offers online or other forms of support.

• Unlike other storage technologies such as floppy, CD, DVD, and tape, media for removable-media drives is usually proprietary and can only be obtained from the original manufacturer in most cases.

• Most removable-media drives require special drivers to function. As new versions of Windows and other operating systems are delivered, a removable-media drive that works, mechanically speaking, might not be compatible.

The following sections provide additional detail about current models

Iomega Zip

Although Iomega Zip drives are no longer as popular as they were in the late 1990s, their widespread industry adoption and easy media and drive availability make them the leading andwith the demise of SuperDiskthe only bigger-than-floppy magnetic removable-media storage de facto standard. Various models can be purchased as upgrades for existing computers, and media is available from both Iomega and Fujifilm.

Unlike the LS-120 and LS-240 SuperDisk drives, the Iomega Zip drive can't use standard 3 1/2" floppy disks. It is a descendent of a long line of removable-media drives from Iomega that go back to the first Bernoulli cartridge drives released in the early 1980s.

Zip 100 drives can store up to 100MB of data on a small removable magnetic cartridge that resembles a 3 1/2" floppy disk. The newer Zip 250 drives store up to 250MB of data on the same size cartridge and can read and write to the Zip 100 cartridges. The most recent Zip drive holds 750MB of data. It's available in separate ATAPI internal versions for PC and Mac and in USB 2.0 and FireWire (IEEE 1394a) versions for use with both platforms. It has read/write compatibility with Zip 250 media, but it has read-only compatibility with Zip 100 media. For best performance, you should use the native media size with Zip 250 and Zip 750 drives; these drives read and write much more slowly when smaller Zip media is used than when their native media size is used.

Iomega REV

Iomega REV was introduced in 2004. It is designed to be used in several ways:

• Backup. REV provides capacity comparable to that of DAT 72 or DLT VS80 tape drives while providing faster read and write access.

• Primary storage. REV can be used as a bootable hard disk. The drive supports all common internal and external interfaces.

• Additional storage. REV cartridges use a rigid removable disk (RRD) design that provides a sealed, air-filtered environment for read/write heads and electronics and a spin rate of 4,200RPM, which is comparable to many notebook computer hard disks.

REV uses 35GB hard-disktype removable-media cartridges. In drag-and-drop file transfer tests, REV drives offer comparable transfer rates to 30GB ATA/IDE hard disks with files up to 64KB in size, and they are much faster with files of 1MB or larger. The maximum data transfer is up to 25MBps.

Iomega REV Capacity

The native capacity of any Iomega REV drive is 35GB. Iomega claims a maximum compressed capacity of 90GB (2.6:1), based on testing performed with the Calgary Corpus data set. However, most users will not see this level of data compression in most real-world operations. The reason is that the files used in the Calgary Corpus were primarily text files. As you'll learn if you spend any time using PKZip, WinZip, or the built-in Zip-compatible Windows XP archiving feature, text files can be compressed up to 90% smaller than normal. However, a great deal of the data on today's systems is already compressed data, such as JPEG photos, PDF files, MP3 and WMA audio files, Zip and cab archives, and so forth. A better estimate for compression performance is to assume a maximum capacity of 70GB (2:1 compression), as is assumed by most third-party backup products.

Iomega REV Drives

Iomega offers a wide variety of drive interfaces for REV, enabling you to choose a drive for almost any type of internal or external host adapter.Note that all drives include Iomega Automatic Backup Pro for Windows 2000 and XP.

Adaptations of Iomega REV Technology

Iomega REV is not just a PC-based backup and storage technology. Iomega manufactures a 10-cartridge autoloader known as the REV Autoloader 1000 for servers. It includes CA Brightstor ARCServe Backup OEM edition for a single server, and it connects to a server via a 68-pin LVD SCSI connection. Options include a bar code reader, a remote management unit, and 2U rack-mounted hardware.

Thomson (www.thomson.net) has adapted the Iomega REV for IT-based video recording purposes as part of its Grass Valley Infinity line of DV camcorder and recorder products introduced in 2005. These devices also use a new version of the REV cartridge known as the REV PRO as well as solid-state Compact Flash memory for video recording.