Section 7.1. High-Capacity FDD Types


7.1 High-Capacity FDD Types

Although many types of high-capacity FDDs have been announced, and some have even been produced in small numbers, the only high-capacity FDDs that have achieved even moderate market penetration are the Iomega Zip Drive and the Panasonic SuperDisk Drive. The following sections detail these drives.

7.1.1 Iomega Zip Drive

The Iomega Zip Drive is the direct descendant of the Iomega Bernoulli Box, a mass storage device that was a popular (and expensive) add-on for IBM XT/AT systems and compatibles throughout the 1980s. The first Bernoulli boxes used 8" 10 MB cartridges. Later models used 5.25" cartridges that ranged from 20 MB to 230 MB. Various single- and dual-drive Bernoulli Box models were available, but they never achieved mass-market success because the drives were very expensive and used expensive cartridges that required periodic replacement.

A Bernoulli cartridge was in effect a large floppy diskette contained in a plastic shell. As the disk rotated, differential air pressure called the Bernoulli Principle, hence the name pulled the disk toward the heads, with which it remained in contact while the drive was spinning. This meant that Bernoulli cartridges wore out relatively quickly, and many users spent as much on cartridges as on the drive itself. But in the days when hard drives were slow and held only 10 or 20 MB, the Bernoulli Box was a reasonable solution for people who needed a lot of disk storage for databases and similar applications. The Bernoulli Box was as fast as a hard drive, or nearly so, and one could expand storage simply by buying additional cartridges, a revolutionary concept in those days.

By the late 1980s, as hard drives increased in size and performance, the Bernoulli Box was becoming obsolescent. But the technology was still sound, so Iomega repositioned the Bernoulli Box in a smaller, cheaper form as supplemental rather than primary storage, and named it the Zip Drive. In effect, Iomega shrunk the Bernoulli Box and its cartridges to a standard 3.5" form factor. The Zip Drive was inexpensive, had large capacity and reasonably high performance for the time, and so became a popular accessory for those who needed removable, transportable storage.

As the '90s ended, the Zip Drive had fallen prey to the march of technology, just as the Bernoulli Box had a decade earlier. Although Iomega increased the capacity and performance of the Zip Drive marginally, other technologies notably CD writers provided superior and less expensive solutions in the niche formerly dominated by the Zip Drive. The Zip Drive might ultimately have replaced the standard floppy drive but for two problems: its inability to function universally as a boot floppy in standard systems, and the very high cost of Zip disks. Had those problems been addressed, the Zip Drive might have become ubiquitous. They were not, and so the Zip Drive is rapidly fading from the scene.

As the market for the Zip Drive disappears, Iomega still claims "millions of users" for the Zip Drive. That sounds impressive until one realizes it means that hundreds of millions of systems have been built without Zip Drives. So, in fact, although millions of Zip Drives have been sold, they are now seldom installed in new systems and have become very much a niche product. But those millions of drives do make the Zip Drive a standard of sorts, to the extent that there can be any standard in a market as fragmented as high-capacity floppy disk drives.

Iomega currently produces three versions of the Zip Drive, which are detailed in the following sections. The Zip100 Drive

The Zip100 drive is available in numerous variants, including internal ATAPI/IDE and SCSI models and external parallel port, SCSI, and USB models. Iomega once produced the Zip Plus model, which had both SCSI and parallel port interfaces, but that model is no longer made. In addition to the standard internal models, Iomega produces several specialized internal IDE units designed to fit particular notebook systems. Various third-party manufacturers have produced internal and PC card models for specific notebook computers.

Unfortunately, Zip Drives cannot read, write, or boot from standard 3.5" 720 KB or 1.44 MB floppy disks, which makes it impractical to use them as the sole floppy drive in most systems. Zip100 drives use a 3.5" disk cartridge that's about twice as thick as a standard 3.5" floppy diskette and stores a nominal 100 MB. Zip100 disks can be read and written by Zip100 and Zip250 drives, but Zip100 drives can use only Zip100 disks.

Some (but by no means all) recent computers and motherboards explicitly support the Zip Drive in BIOS Setup. On such systems, you can enable an ATAPI/IDE Zip Drive as a boot device. If you do so, you need not install a standard floppy disk drive in that system unless you need compatibility with standard floppy disks.

Like standard floppy disks, Zip disks must be formatted before data can be stored on them, although preformatted Zip disks are readily available. Two formatting methods are available. A long format requires 10 minutes or more and corresponds to a full format on a standard floppy disk. The long format actually formats the entire disk and verifies the surface. A short format requires only 10 seconds or so, and corresponds to a Quick Format on a standard floppy disk. The short format simply zeros out the FAT and root directory without actually formatting the disk or verifying its surface. As with standard floppies, a short format can be done only on a disk that has previously had a long format done on it.

Regardless of interface, all Zip100 drives provide track-to-track, maximum, and average seek times of 4 ms, 55 ms, and 29 ms, respectively. Because all Zip100 drives spin at 2,941 RPM, average latency is about 10.2 ms, yielding average access times of about 39 milliseconds, much slower than a hard drive but noticeably faster than CD and DVD recorders. The typical start time for Zip100 drives is about three seconds, which is the delay between inserting a disk and when that disk can be read or written. Overall, regardless of the interface, Zip100 drives "feel" somewhat faster to us than standard floppy drives when reading or writing one or a few small files, and much faster when writing many (or large) files.

The sustained transfer rates, burst transfer rates, and average throughput of Zip100 drives vary according to interface.

  • All Zip100 drives provide a minimum sustained transfer rate of 0.79 MB/s, which is determined by the drive mechanism.

  • All Zip100 drives have a potential maximum sustained transfer rate of 1.40 MB/s, again determined by the mechanism and internal interface, but in practice only the ATAPI/IDE and SCSI models are likely to achieve anything near this rate. In our experience, parallel models provide slower sustained transfers, much slower if the parallel port is an older model or is misconfigured. USB models are limited by the USB interface to 12 Mb/s, which translates to a maximum sustained transfer rate of 1.20 MB/s.

  • The burst transfer rate of Zip100 drives is limited by the internal interface to 26.7 Mb/s, but again only the ATAPI/IDE and SCSI models are likely to come close to that rate. The parallel and USB models are limited by their interfaces to less than ~20 Mb/s and 12 Mb/s respectively.

  • Iomega specifies the typical throughput for all Zip100 drives as 60 MB/minute, except the parallel model, which they specify as 20 MB/minute. Based on our own experience, those numbers may be a bit high. Using an ATAPI/IDE or SCSI Zip100 drive, it typically takes us between two and five minutes to copy a full disk to or from a fast hard drive noticeably slower than the rated throughput and it takes much longer if many small files are being copied. We also find that the parallel and USB models are correspondingly slower than their rated throughput in real-world use. The Zip250 Drive

When the Zip100 Drive was introduced, its capacity and performance were reasonable for the time. In those days of smaller hard drives, many people could back up their entire hard disks to one or two Zip100 disks. But as the years passed, faster systems with larger and faster hard drives were introduced, and newer versions of applications programs continued to generate larger and larger data files. Iomega realized that the Zip100 Drive was fast becoming too small and too slow to be useful for many users, so they introduced the Zip250 Drive, which provides more than twice the capacity and somewhat higher performance.

The Zip250 drive is available in the same interfaces as the Zip100 Drive: ATAPI/IDE, parallel port, SCSI, and USB. Iomega also produces PC Card and FireWire adapters that allow the USB Zip250 Drive to be used with those interfaces. Like the Zip100 Drive, the Zip250 Drive cannot read, write, or boot from standard 1.44 MB diskettes. The Zip250 Drive accepts both Zip100 disks and Zip250 disks, although we've found that using Zip100 disks negates the performance benefits of the Zip250 Drive. Still, the fact that the Zip250 Drive can read or write any Zip disk makes it the best candidate for a system that requires a Zip Drive for whatever reason.

The Zip250 Drive uses the same rotation rate as the Zip100 Drive, and provides comparable seek and access times, with one exception. The USB Zip250 Drive specifies average seek time as less than 40 ms, noticeably slower than the other models. ATAPI/IDE, parallel port, and SCSI Zip250 Drives specify sustained transfer rates of 1.2 MB/s minimum and 2.4 MB/s maximum, although in our experience the parallel port model in fact has about half the transfer rate of the SCSI and ATAPI/IDE models. The USB Zip250 Drive provides maximum sustained throughput of 1.4 MB/s when using the USB interface, 0.9 MB/s with the PC Card adapter, and 2.3 MB/s with the FireWire adapter.

Although the Zip250 Drive is marginally larger and faster than the Zip100 Drive, we believe the Zip250 is too little and too late to establish a lasting niche. With the Zip250, Zip technology appears to have reached its limits, so we don't expect ever to see larger or faster Zip Drives. Many people continue to use Zip Drives, and even to buy new ones, but we think that in a very few years Zip Drives will be only a memory. If you must have a Zip Drive, the Zip250 Drive is the one to get, but we suggest thinking carefully before buying any Zip Drive at all. The PocketZip Drive

As the market for traditional Zip Drives began shrinking, Iomega struggled to reposition their technology yet again. They focused initially on an existing market notebook computer users and on two burgeoning markets, digital cameras and portable MP3 players. Digital cameras, of course, generate many large image files, and MP3 collectors tend to accumulate audio files by the gigabyte. Iomega considered Zip technology an ideal alternative to the flash memory devices such as SmartMedia cards and CompactFlash cards used by most digital cameras and MP3 players, because Zip cartridges could be produced and sold much more cheaply than solid-state memory cards.

And so in 1998 Iomega introduced the Clik! Drive, which they later renamed the PocketZip Drive. In effect, the PocketZip Drive is a miniaturized Zip Drive. The first model, the Clik! Mobile Drive, was an external drive that connected to a notebook computer via a PC Card adapter. That drive was soon discontinued, and has been replaced by three PocketZip drives:

  • PocketZip Built-in Drive. This drive is targeted at hardware manufacturers rather than consumers, and is intended, as its name suggests, to be built into such devices as digital cameras and MP3 players.

  • PocketZip PC Card Drive. This drive inserts directly into a PC Card Type II slot, and is intended for backing up data from a notebook computer and transferring data between a notebook computer and other notebook computers and desktop systems.

  • PocketZip USB Drive. This external drive interfaces via USB with any notebook or desktop computer system that has an available USB port and runs a USB-aware operating system. Although it is much larger than the internal versions, it is small and light enough to be easily portable.

Iomega also produces the PocketZip Docking Station, which connects to a computer via USB and provides a connection point for a PocketZip PC Card Drive, allowing that drive to be shared easily among multiple computers, including desktop computers that do not have a PC Card adapter.

PocketZip Drives use only the PocketZip disk, which is a smaller version of the standard Zip disk. It is about 2" square, 3/4" thick, weighs less than half an ounce, stores about 40 MB, costs $10 or so, and has performance similar to a standard Zip Drive.

Although a few digital cameras and other small devices use the PocketZip drive natively, the PocketZip has not been widely adopted, nor do we think it ever will be. If you have a digital camera, MP3 player, voice recorder, or other device that uses PocketZip disks, it's worth buying a PocketZip USB Drive to transfer data between your computer and that device. We see little purpose for the PocketZip PC Card Drive, however. Anything it does is better done by an external USB CD writer or, alternatively, a PC Card hard drive, both of which offer considerably more capacity, performance, and flexibility at relatively small additional cost, particularly when the ongoing cost of buying PocketZip disks is taken into account.

7.1.2 SuperDisk Drive

The only serious competitor to the Zip Drive in the high-capacity floppy drive segment is the SuperDisk Drive, the most frequently encountered variant of which is the Imation LS-120 drive. The SuperDisk Drive was developed by Matsushita-Kotobuki Industries (Panasonic), Compaq, Imation, and others. It was intended to be a universal replacement for the standard 3.5" 1.44 MB floppy disk drive, a goal that it has failed to achieve.

Imation, a major OEM source of the SuperDisk Drive under the Imation LS-120 brand name, stopped selling LS-120 drives in early 2001, although they continue to support the drives and manufacture media for them. Even though Panasonic and other vendors still sell SuperDisk drives in fact new models are still being introduced Imation's departure from the market makes the long-term viability of the SuperDisk Drive questionable. At this point, it is unclear if Imation will OEM the new generation 240 MB SuperDisk Drives or produce drives based on the FD32MB standard.

The SuperDisk Drive has the major advantage that, unlike the Zip Drive, it can read and write standard 1.44 MB floppy diskettes. In addition, the SuperDisk Drive reads data at 27 times the rate of a standard FDD and writes it at about 20 times the rate. The SuperDisk Drive also reads and writes standard 1.44 MB floppy diskettes at up to three times the rate of a standard FDD. Many recent PCs and motherboards provide native BIOS boot support for the SuperDisk Drive, which allows it to be used as the only FDD in a system. Some Compaq systems have come standard with a SuperDisk Drive, although the drive is an extra-cost option on most of the few systems that offer it.

The performance of the SuperDisk Drive varies by interface, as shown in Table 7-2. The standard 3.5" 1.44 MB FDD is shown for comparison.

Table 7-2. Key characteristics of SuperDisk Drive by interface

1.44 MB FDD

SuperDisk Drive







PC Card

Sustained transfer rate

45 KB/s

1,100 KB/s

750 KB/s

750 KB/s

440 KB/s

Rotation rate

300 RPM

1,440 RPM

1,440 RPM

1,440 RPM

720 RPM

Average read access

~ 185 ms

~ 81 ms

~ 81 ms

~ 81 ms

~ 112 ms

Track density

135 tpi

2,490 tpi

2,490 tpi

2,490 tpi

2,490 tpi

Tracks/side (2 sides)






Buffer size

0 KB

10 KB

10 KB

10 KB

8 KB

The SuperDisk disk closely resembles a standard 3.5" 1.44 MB floppy disk, but can be readily distinguished visually by its triangular media shutter and trapezoidal labeling space. SuperDisk disks can be read and written only in a SuperDisk Drive.


    PC Hardware in a Nutshell
    PC Hardware in a Nutshell, 3rd Edition
    ISBN: 059600513X
    EAN: 2147483647
    Year: 2002
    Pages: 246 © 2008-2017.
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