Microsoft's radically different Windows 8 software is meant to work equally well in the mouse- and keyboard-driven world of desktop PCs and laptops and in the multitouch universe of tablets. And that challenges computer makers to come up with hardware designs that are equally flexible.
I've been testing two innovative, if imperfect, new Windows 8 ultrabook computers that meet the design challenge, within limits. There's the IdeaPad Yoga 13 from Lenovo and the Satellite U925t ultrabook convertible from Toshiba.
Lenovo's Yoga is so named because the touch-screen computer can be folded and flipped 360 degrees into four distinct positions, starting in a standard clam-shell mode as a rather handsome laptop. You can also bend the display so that it faces you, with the rest of the computer serving as an out-of-the-way stand. This "stand mode" is good for viewing movies on an airplane or in other tight quarters.
A third "tent mode" lets you prop up the computer like a tepee, which Lenovo says is ideal for browsing pictures or recipes. I also watched a movie that way.
The last mode turns Yoga into a full-fledged tablet, and in some respects this is its most disappointing posture. The reason is that the underbelly of the machine exposes the physical keyboard and though the computer is smart enough to disable the keys when you carry the machine around like a tablet, it all feels rather unnatural. I can't see spending much time reading on it that way, either.
Lenovo also disables the physical keyboard in stand mode and tent mode, leaving you to rely solely on the onscreen touch keyboard.
The keyboard isn't exposed when you're using Toshiba's Satellite U925t as a tablet, but it's also a bit unwieldy. It's not immediately obvious how to transform the machine from a tablet to a laptop and back. You press your thumbs against the screen, pushing it as far back as it will go, then fold the screen up to reveal the keyboard and track-pad concealed underneath. It's rather awkward, but you get used to it.
Both machines are at their best as conventional laptops.They have very usable physical keyboards and track-pads. At the same time the gesture-friendly Windows 8 interface, which is built around a live tile interface, all but begs you to tap, swipe, pinch and otherwise touch the screen, at least when you're working with the latest Windows 8 apps. Touch may not be the way most of us grew up with computers, but it is very common behavior on smartphones and tablets, and Microsoft hopes it will become so on PCs, too. And that's where the computers' versatility becomes a big deal.
The machines run the full version of Windows 8, the flavor that's compatible with your old Windows software, much of which was produced for the mouse and keyboard age. Neither currently runs a Win 8 variant known as Windows RT, which is not compatible with older apps. Lenovo plans to bring out an 11-inch version of Yoga next month that does run RT; Toshiba is sticking with the full Windows 8 for now.
After spending time with these computers, I don't think either the Lenovo Yoga or the Toshiba Satellite represent true iPad substitutes, so much as flexible replacements for notebooks and laptops. (I suspect the companies agree.)
Both weigh in at around 3.3 pounds, by no means heavy for a laptop. And they're relatively thin compared with many notebooks. But they are more than double the weight of the iPad and are a good deal thicker.
Then again, the iPad doesn't function as a laptop like either of these ultrabooks, and it doesn't have a physical keyboard.
My Lenovo test configuration, sold at Best Buy for $999.99, has a third-generation Intel Core processor, 4 gigabytes of memory and a modest 128 GB solid-state drive, which actually provides just over 50 GB of available space for the stuff you want to store, because system files hog so much room. Yoga has a single USB 3.0 port, a single USB 2.0 port, plus HDMI for hooking it up to a large high-definition TV. There's also a memory card reader on board and Dolby Home Theater sound.
The Toshiba Satellite is similarly equipped - except it adds a second webcam, NFC (Near Field Communication), has two USB 3.0 ports and relies on SRS Premium Sound 3D technology for audio. But it costs more, too - a rather steep $1,149.99.
What's more, the 12.5-inch widescreen display on the Satellite, while decent, loses a side-by-side comparison against the much nicer 13.3-inch screen on the Lenovo. Toshiba's screen is exposed when you carry the slate around, but it's protected by Gorilla Glass. I preferred typing on the rounded Lenovo keyboard, too, though Toshiba gains brownie points for supplying a back light on its keyboard that the Yoga unfortunately lacks.
Yoga also beat the Toshiba on battery life, though neither machine delivered outstanding results in my harsh test. I streamed movies over Wi-Fi and had the screen cranked up to its brightest setting. The Lenovo lasted about four hours, 35 minutes, roughly a half hour longer than the Toshiba. Expect to do better under less-harsh conditions.
I also ran into a problem in which the Satellite dropped a Wi-Fi connection that the Lenovo was able to hold onto.
You can expect to see more inventive hybrids in the coming months. Consider that a good thing. The Toshiba and the Lenovo especially get kudos for innovation. But neither has achieved perfection.
Follow @edbaig on Twitter. E-mail: email@example.com.
The bottom line
Lenovo IdeaPad Yoga 13
Pro. Clever 360-degree hinge lets you fold and bend machine into notebook, stand, tent and tablet modes. Lovely screen and excellent keyboard.
Con. Awkward as laptop. So-so battery life. Limited storage.
Toshiba Satellite U925t
Pro. Can be converted from laptop to slate. Backlit keyboard.
Con. Disappointing battery. Screen is just OK. Limited storage.