Can the Asus hybrid reheat the tablet market?

Remember when tablet computers were cool? They still are, but in the wrong way.

Sales of Apple Inc.’s iPad, for example, are downright frigid, having fallen for the past two quarters. Samsung Corp., the number two tablet maker, is still growing, but barely. Amazon.com sells huge numbers of nearly everything, but not too many of its Kindle Fire tablets. All the action’s on the low end: Cheap generic Android tablets are doing fine, especially in developing countries. But the industry’s technology leaders are suddenly icebound.

No wonder. In the United States and other wealthy countries, nearly everyone who wants a tablet has one. And they don’t need constant upgrading. Even a three-year-old iPad 2 is still a pretty good machine. So what will it take to get us shopping for new tablets?

Maybe a radically different kind of tablet. That’s the theory of Taiwanese computer maker Asus, creator of the Asus Padfone X. This odd little hybrid — a tablet and phone in one — might find a niche for itself because it’s cool and cheap. In effect, Asus is selling a decent quality smartphone and throwing in a pretty good tablet computer at no extra charge.

The Padfone X costs $549.99 full price, or $199.99 with a two-year service contract from AT&T Inc. And you might be able to do even better at Amazon.com, which recently offered the Padfone X for just $99.99

You get a sleek, black Android phone with the usual high-end features. There’s a 5-inch screen, a quad-core processor, and a 13-megapixel camera that takes respectable photos — accurate color, but a bit grainy. The phone’s rear cover pops off to reveal a slot for adding up to 64 gigabytes of flash memory to the 16 gigs already built in. In all, it’s just another smartphone, no better than rival products from Samsung or HTC, but just about as good.

The Padfone X tablet features a high-resolution 9-inch screen, a pair of pretty good stereo speakers, a one-megapixel front-facing camera, and no brain at all. The tablet comes to life only when the phone is plugged in. The handset slides into a cradle built into the back of the tablet. The two pieces glide into place with an elegant, authoritative snap. In a second or two, the tablet lights up and gives you full access to the phone’s apps and services, as well as Android apps designed for tablet use.

The transition can be wonderfully seamless. For instance, you can shoot a photo with the phone, then snap it into the tablet and instantly admire your handiwork on a larger screen. Or you can answer an incoming call using the tablet’s speakerphone, but switch to the phone handset in mid-call for more privacy.

Many independently produced apps lack this easy switching feature. For instance, if you start a YouTube video on the phone, you must relaunch the app when switching to the tablet. But this is a trivial annoyance, and hardly a dealbreaker.

The Padfone tablet is too bulky for my taste, and the screen is surrounded by a thick bezel that takes up much of the available real estate. Still, it feels comfortable in the hand, and the screen delivers sharp resolution, making it a good platform for movie-watching and casual gaming.

The tablet’s battery is big enough to drive it and the phone for a couple of days, though it will drain much faster under heavy use. Four hours of streamed videos got the battery down to 47 percent power. But you can recharge both devices simultaneously through the AC power adapter, or use the tablet’s battery pack to give the phone’s smaller battery a boost.

The Padfone X could be an excellent bargain for tablet users who need constant Internet access, because you won’t need a separate 4G cellular data plan for the tablet.

Instead, the Padfone uses a single data account, whether it’s used as a phone or as a tablet. As long as you stay in AT&T country, your tablet will never be offline, and you won’t pay extra for the privilege.

If you want the best phone on the market, or the finest tablet, the Padfone X isn’t for you. The inevitable compromises of its hybrid design keep this gadget out of the top tier.

But its innovative design and remarkably low price make it one of the best technology deals of the year, and easily one of the coolest.