Zip drive

Design

The Zip system is based loosely on Iomega's earlier Bernoulli Box system; in both systems, a set of read/write heads mounted on a linear actuator flies over a rapidly spinning floppy disk mounted in a sturdy cartridge. The Zip disk uses smaller media (about the size of a 3.5" microfloppy, rather than the compact disc-sized Bernoulli media), and a simplified drive design that reduced its overall cost.

This resulted in a disk that has all of the 3.5" floppy's convenience, but holds much more data, with performance that is much quicker than a standard floppy drive (though not directly competitive with hard drives). The original Zip drive had a data transfer rate of about 1 megabyte/second and a seek time of 28 milliseconds on average, compared to a standard 1.4 MiB floppy's 500 Kbit/s transfer rate and several-hundred millisecond average seek time.

Capacity

The initial Zip system was introduced with a capacity of 100 megabytes, and quickly became a success as people used them to store files larger than the 1.44 MB capacity of regular floppy disks. As time went on, Iomega eventually increased the capacity to 250 and later 750 megabytes, while improving the data transfer rate and seek times.

Media

Zip media is similar in vertical size (but thicker) than 3.5" floppy disks, which means the drive slot is large enough to accept such a floppy. To prevent drive and disk damage, the underside of Zip media cases include a retroreflective spot in one corner. The drive mechanism will not engage if the reflective spot is not detected.

Compatibility

Higher capacity Zip disks must be used in a drive with at least the same capacity ability. Generally, higher capacity drives also handle all lower capacity media, although the 250 MB drive is much slower than the 100 MB one to write data on a 100 MB disk. The 750 MB drive, however, cannot write to the 100 MB media, which is the cheapest and most common.

Features and implementation

Unlike other diskette formats, the Zip's write protection is implemented on the software level instead of mechanically enforced in the hardware. The metadata on the disk indicates the write protection status, which the software driver then enforces to the operating system. This means that the disk must be loaded in a drive and accessed on a computer to turn write protection on or off. It also means that, in theory, a rogue driver could be created which ignores the write protection flag.

The Zip system also introduced media access protection via a password. Like write protection, this is also implemented on the software level. One side effect of this implementation is that, on some drive models, it is possible to trick the software into allowing access to a different disk than it believes to be in the drive, thereby bypassing the password protection.

Sales, problems, and licensing

Sales of Zip drives and disks declined steadily from 1999 to 2003. In September 1998 a class action suit was brought against Iomega over a type of Zip disk failure dubbed the click of death. Zip disks also have a relatively high cost per megabyte compared to the falling costs of CD-R and DVD±RW technology.

The Zip disks' suppliers include: Iomega, Fujifilm, Verbatim, and Maxell. Epson also produced a licensed 100MB drive model with their brand name.

Iomega also produced an early line of external recordable CD drives using the Zip brand in the late 1990s, called the ZipCD 650. It used regular CD-R media and had no format relation to the magnetic Zip drive.

References

See also