Ever since Apple introduced its iMac series of computers, featuring a conspicuous lack of floppy drive, people have been speculating an early retirement for the floppy disk. The floppy's capacity is nowadays relatively small, its speed ain't so racy, and its design just isn't hip anymore. Floppies, the PC-user's memory-mules of choice since 1981, have finally reached their best-before date.

If Apple prognosticated the demise of the floppy, then it's heralding its latest successor, too. The zip disk is around the same size as your average 3.5inch floppy, but it holds almost 100 times as much data, is speedier to access, and more stable to use. That said, the zip disk -- as well as the larger-format diskettes that preceded the 3.5inch floppy -- operates on the same principle as the floppy disk. A brief explanation of those principles follows here.

At the core of the floppy disk is something called the media, which consists of a plastic disk coated in a chemical compound that is sensitive to magnetic impulses - basically, rust. The information you save or download from floppies is converted to magnetic signals. When you insert a floppy into your computer's disk drive, a mechanism retracts the metal sheath that protects the media, so that it becomes exposed to the drive's read-write heads. These heads register magnetic impulses from the disk, or else encode them onto the disk. In order to relay data from the disk to the computer, the magnetic impulses are converted to electrical currents that the computer -- if not its human operator -- understands.

In order for read-write heads to glean information from diskettes, those diskettes must rotate. The computerized muscle that effects this task is called the spindle motor. It's connected to something called the hub clamp, which grips the disk's hub. The hub looks like a small, circular metal disk on the bottom of the floppy, and it represents the only exposed portion of the media. When it spins around, the rest of the media spins around, and the read-write heads are able to exchange signals with the surface of the media. Data is stored in strings around the media, much like the grooves in a record.

One of the reasons floppies are not the most reliable means of storing information is that the read-write heads must come into physical contact with the media, which causes wear and tear. Another reason floppies are unstable is the mechanism that drives the read-write heads across their surface. In order to find a particular strand of information, the read-write heads are guided by the stepper motor which moves them towards the inside or outside of the disk. Zip disks, by contrast, feature a much smoother read-write motion, with less jarring and potential corruption of data.

When you first insert an unused disk into your computer's A-drive, the PC will ask you to format that disk. This process divides the media into tracks and sectors. Tracks are the rings that circle the media, and sectors are equal-length segments of those rings. The determine how information will be stored on the floppy. By contrast, a zip disk requires on formatting at first use; only if the disk is travelling between PCs and Mac computers will you be prompted to reformat it.

If all these details on floppies are too hard to understand, you might consult the simpler, more useful guide of John Kinsella, the Manager of Computer Systems at the University of California at Davis. If his manual, at here, doesn't bring a smile to your face, then you really are hard to please.