Removable Magnetic Storage Devices

A small group of companies dominates the fading market for magnetic removable-media drives. 3M's spin-off company Imation, Iomega, and Castlewood are the leading names in removable magnetic media drives and media offering higher capacities than standard floppies.

Removable magnetic media drives are usually floppy or hard disk based. For example, the popular Zip drive is a 3 1/2'' version of the original Bernoulli flexible disk drive that Iomega manufactured. The SuperDisk LS-120 drive is a floppy-based drive that stores 120MB on a disk that looks almost exactly like a 1.44MB floppy; the second-generation LS-240 SuperDisk drives store up to 240MB and can format standard 1.44MB floppy disks to hold 32MB of data! The Castlewood Orb drives are all based on hard disk technology.

Although they are no longer as popular as they were in the late 1990s, from the standpoint of widespread industry adoption and multiple sources of media, both the LS-120/240 SuperDisk and Zip 100/250 drives can be considered some type of industry standard. Various models can be purchased as upgrades for existing computers, and third-party media vendors such as Maxell, Verbatim, Sony, and Fujifilm sell Zip and SuperDisk media. The following table shows the Ultrabay 2000 SuperDisk and Zip drives sold by IBM for their ThinkPad line:

IBM ThinkPad Drive Options	P/N	FRU [*] P/N
Ultrabay 2000 SuperDisk (LS-240) Drive	08K9616	08K9615
Ultrabay 2000 Zip 250MB Drive	00N8253	00N8254

^[*] FRU = Field Replacement Unit, or repair part.

These drives work in any ThinkPad systems that use the Ultrabay 2000 modular bay standard, including most A, R, T, and X series systems, and can store the equivalent of up to 166 traditional 1.44MB diskettes (240MB) on one SuperDisk or 173 1.44MB diskettes (250MB) on one Zip 250 disk. The LS-240 drive is backwards read/write compatible with existing 720KB, 1.44MB, and LS-120 media and transfers data up to 20 times the speed of a standard 1.44MB diskette drive. The Zip 250MB drive is backward read/write compatible to the industry standard Zip 100MB media.

The following sections provide information about all types of magnetic media, including floptical and magneto-optical drive types.

Iomega Zip

Unlike the LS-120 SuperDisk, 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.

The current form of Bernoulli-technology drive from Iomega is the popular Zip drive. These devices are available in 100MB, 250MB, and 750MB versions with either ATA (internal), USB (external), or FireWire (external) interfaces. They also sell specific external models with either SCSI or parallel port interfaces. In addition, low-power PC Card or internal drive bay versions are available from various portable computer manufacturers or aftermarket vendors designed for use in laptop computers.

Zip drives use a proprietary 3 1/2-inch disk made by Iomega and also sold by other major media vendors, such as Maxell, Verbatim, and Fuji. It is about twice as thick as a standard 3 1/2-inch floppy disk or SuperDisk (see Figure 10.18).

Figure 10.18. The Zip 100MB disk (right) compared to the standard 3 1/2-inch 1.44MB disk (middle) and the LS-120 SuperDisk (left).

The Zip drives do not accept standard 1.44MB or 720KB floppy disks, making them unlikely candidates for a floppy disk drive replacement.

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 latest Zip 250 cartridges have a U-shaped case and use media containing titanium particles for greater durability. 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 1394/i.LINK) 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.

SuperDisk LS-120 and LS-240

Imation developed the LS-120 SuperDisk in the late 1990s as a rival to the Iomega Zip disk. The SuperDisk uses floptical technology, which uses laser servo (LS) optical tracking to precisely position read-write heads on floppy-type media. In other words, a laser beam is used to guide the magnetic heads. Although the SuperDisk is capable of reading and writing to standard 1.44MB and 720KB floppy media as well as to its own 120MB media, it was unable to overcome the huge lead Iomega had gained by being first to market with the Zip drives and media in the mid-1990s. Imation and other vendors still sell LS-120 media, but most LS-120 SuperDisk drive products have been discontinued.

The second-generation LS-240 SuperDisk uses both LS-120 and its own 240MB LS-240 media. It can also write to standard 1.44MB and 720KB floppy disks and format a 1.44MB floppy disk to hold 32MB of data. However, similar to its predecessor, it has been unable to make a significant impact in the marketplace . The first LS-240 SuperDisk drives were produced for the OEM market as internal ATAPI drives, but in the U.S. retail market, most have been sold for use with either USB interfaces or the proprietary removable-bay features of some high-end notebook computers. USB-based LS-240 SuperDisk drives have been sold in the U.S. by QPS (www.qps-inc.com) and Addonics (www.addonics.com). Several notebook computer vendors, including HP and IBM, also made versions for the interchangeable drive bay featured on some of their notebook computer models. Most of these drives have been discontinued, but some are still available at some dealers.

Figure 10.19 shows the media types that are compatible with the LS-120 drive.

Figure 10.19. A standard 1.44MB 3 1/2-inch floppy disk (left) compared to LS-120 SuperDisk media (right).

Note

SuperDisk drives can use either SuperDisks or standard 3 1/2-inch floppies. Because the media sense hole and write-protect/enable slider are on opposite sides of the media, the SuperDisk is protected from damage if it is inserted into an ordinary floppy drive by mistake.

Hard Disk “Based Removable-Media Drives

The Castlewood Orb drives feature 2.2GB and 5.7GB capacities and are essentially small hard drives with removable media. You can install an entire operating system and a major application on these cartridges and boot from them to completely customize your system's operation. Unfortunately, these drives use proprietary designs, so the drives and media are available only from the manufacturer and are not interchangeable with other companies' products. I usually do not recommend proprietary products, preferring instead devices that are more industry standard.

Because of the popularity of external hard drives that interface through USB and FireWire (IEEE 1394/i.LINK) ports and rewritable DVD drives, this category of removable-media drives has also been declining in popularity over the last couple of years .