Its insides would warm the heart of a Swiss watchmaker -- tiny, finely crafted components whirring, reaching, spinning in choreographed precision, doing their duty year after year with razor-sharp accuracy and reliability.

Your computer's hard disk is one of the last preserves of mechanical engineering in a computer, working much of its magic with moving parts. And the technology keeps getting better and cheaper, despite perennial predictions of its ultimate demise.

There was new proof last week from diskmaker Seagate Technology Inc. There, engineers have succeeded in creating a recording density of 23.8 billion bits of data per square inch of storage medium. As a product (lab developments like this generally take about two years to make it onto the market), that would equate to storing 32 gigabytes on a single 3.5-inch disk.

With announcements like that, the hard-disk industry claims to do better than the famous "Moore's Law" of microchip progress. That law says that chips are meant to double in performance roughly every 18 months; diskmakers say they manage that about every 12.

The strange thing is that despite such accomplishments, the hard disk gets so little respect. We love to hate it, accusing it of failing far more often than it actually does. For the most part the things keep chugging along, and new ones get more reliable by the year.

Hard-disk designers improve capacity through three basic strategies. One is to shrink the width of the data-storing magnetic tracks that circle the disk. Another is to cram more bits into each track. It's the same game of miniaturization that's played in chip development, except that mechanical heads have to be able to find their way to specific spots to scoop up or lay down data.

The third approach is to add platters. Though we refer to a hard disk in the singular, the one in your computer may have multiple platters stacked on top of one another like records in a jukebox, each read by different heads. This lets designers increase capacity without increasing the density that a given square inch of disk can hold.

How far they've brought us these past years. When I bought my first PC in 1990, the question was whether to get 20 or 40 megabytes of storage (there was a substantial difference in price). If I bought one today, nine years later, the head-scratcher would be whether to go with 4 gigabytes or 8 -- in other words, a range 200 times higher. Not bad.

John Monroe of market research firm DataQuest in San Jose says that hard-disk storage cost about $5.46 per megabyte at the factory gate when I bought that computer way back when. Today it's about 2 cents. Nine years, and a better than 99 percent drop in cost. Pretty impressive.

There's never a shortage of predictions that other media -- optical disks, flash memory -- will replace the hard disk, yet it keeps its status as boss year after year. The other products, while they advance like everything else in this industry, never quite seem to live up to their billing.

Hard disks seem certain to retain their dominance in the years ahead. With software and files getting ever bigger (witness Office 2000 and all those MP3 music files flying around the Internet these days), people more than ever need low-cost storage and fast access to the data.

International Data Corp. projects that shipments of hard drives this year will grow by 15.5 percent, to 166 million units. That's up from 11 percent growth in 1998.

Faster growth doesn't necessarily translate into better profits in the hard-disk industry, however. Despite their complexity, hard disks have become something of a commodity -- you can take one company's product out of a computer and replace it with another company's without too much fuss. Right now the industry is suffering a glut in production, causing strong price competition and financial pain.

The stock of market leader Seagate, for instance, was above $50 in early 1997. These days, despite the subsequent run-up in the stock market, it's below $30. That's bad news for shareholders, but consumers have done pretty well.

John Burgess's e-mail address is