Humans naturally have the power to remember almost two bits of information per second, or a few hundred megabytes over a lifetime. Compared with a DVD movie, which holds up to 17 gigabytes, that’s nothing. Worse, you might easily recall the 40-year-old dialogue from Hogan’s Heroes yet forget your mom’s birthday. Or memorize reams of sports stats while spacing out on work you completed just last week.

It’s a problem that’s been bothering Gordon Bell for almost as long as he can remember.

For years, the phrase “PDA–phone combo” brought to mind clunky bricks that appealed to only the most connectivity-crazed early adopters. But the latest incarnations of these devices, now known by the more marketing-friendly tag “smartphone,” are finally fit for the rest of us.

So why do you want one?

Beyond the obvious calling capabilities, smartphones keep your calendar and address book close at hand (and ever more easily synced with your PC), provide access to e-mail and the Web,

Your PDA tells you many things—the time of a meeting, the phone number of a colleague. It entertains with games and MP3s. But it does not tell you to step right to avoid a landmine. It does not tell you to pull the trigger. Not unless you are a Marine, that is, and the device is the D-DACT, a PDA the military hopes will do nothing less than take war into the wireless age. Instead of drifting dangerously out of touch, soldiers will be networked through D-DACT modems, which communicate over military radio frequencies.