One component in our pursuit of the tiniest possible office (see "Small Is Useful," October 1991, [Article link]) just got tinier. This past fall Hewlett-Packard began shipping the world's smallest hard drive. The unit stores more than 21 megabytes of information on a 1.3-inch disk, shattering the old mark by almost half an inch. Taking up 2 inches by 1.44 inches by .4 inches in all (about the size of a matchbox), the new disk has screws that can't be seen by the naked eye. A wired array of 60 of these disks will fit into the space of a PC's conventional 5.25-inch drive -- but can store a thousand times more data.

By itself, the one-ounce device holds more than 14,000 typed pages. Easily removable, it will be a boon to a new breed of powerful vest-pocket computers. A sophisticated impact sensor will protect it from damage, even in operating mode. HP claims the aptly named Kittyhawk can survive the inevitable plunge from airplane-seat tray to floor.

Best of all, the tiny device represents a reduction not just in size but in telecommunications bills as well. Typically, traveling executives listen to voice mail over cellular phones -- a costly connection. With HP's mechanism connected, data are transmitted as digital information and stored instantly. The phone call to retrieve the data lasts only a few seconds, but an executive can review the stored messages later at his or her leisure, saving a bundle.

For specifics or referrals, call Hewlett-Packard Direct, 800-637-7740. -- Robert A. Mamis