If you're like me, the selection of a new mobile device doesn't begin with styling, features, or even performance. Rather, I start with what is known as form factor, which is simply the general size and layout of the device. It doesn't matter to me whether a computer is cool (both thermally and in terms of design), hot (in terms of performance only), or otherwise the talk of the Web. I need to start with whether it will fit in my already stuffed computer bag. I prefer small (but not too small) mobile computers that don't weigh very much. I'm always on the road and really not looking for any more of a workout than I already get carrying 12 or so pounds of stuff everywhere I go.
So I thought it would be interesting to enumerate the major categories of mobile computers today. As is the case with handheld devices, we're seeing an increasing diversity of form factors for mobile computers -- this despite a general commonality of operating and applications environments. Let's look at these, from smallest to largest, using Farpoint Group's taxonomy:
- Micro-PCs: This is an intriguing class of PC, currently populated by the Flipstart, the OQO 02, and the Sony VAIO UX Micro PC. The goal here is to fit the desktop OS into as small a package as possible, and all three of these products succeed -- with the inevitable compromises of screen size, processor speed, and battery life. But they are indeed cool and may be exactly what you need to run desktop apps in the smallest possible form factor.
- UMPCs: The Ultra-Mobile PC has not been a raging success, partially because it's bigger than the Micro-PC and priced like an entry-level notebook. There's no hardware keyboard, but even so I think these could be really attractive at a lower price. In fact, I'm betting that the UMPC will form the basis of a future Microsoft smartphone, although I have no information that Microsoft is in fact pursuing this direction.
- Tablets and convertibles: These haven't exactly set the world on fire either, but the form factor and handwriting-based interface (along with handwriting recognition that often works) make these a good option for note-takers and creative types. You can find more information on Microsoft's Web site.
- Subnotebooks: This was for a long time my personal choice in mobile computers. The idea is to build a very lightweight notebook, with a fairly large screen (12 inches), and provide the optical drive and assorted other expansion ports in a "slice" docking station that clips to the bottom of the computer. Thus one can carry only the pieces one needs, saving size and weight in many cases. This idea is fading, however, as universal docking stations and USB-attached optical drives become more common. If you want a subnotebook, though, check out my favorite -- the Lenovo (formerly IBM) X60.
- Ultraportables: The next three categories are all mainstream notebooks (the common "clamshell" design), which are differentiated today primarily by screen size. Ultraportables have a diagonal screen measurement of 12 inches or less. There's little difference in functionality between these three classes; it's really a choice of screen size and the accompanying size and weight penalty as screen size increases. The core advantage of an ultraportable is the inclusion of an optical drive in an otherwise small form factor. This is an excellent choice for anyone who needs a mobile computer for travel but will use a larger screen (perhaps plugged into the ultraportable) for day-to-day work.
- Mainstream notebooks: These have a screen in the range of 13-15 inches and represent the best choice for users who need a computer that must serve in both mobile and office settings. Individual manufacturers will often sell mainstream, entry-level, and high-performance versions within a given class of form factor.
- Mega-notebooks: Finally, many computers on the market today have 17-inch displays, or even larger. Dell even sells a "portable" with a 20-inch display, though I would hardly call an 18-pound computer portable! I don't really think mega-notebooks are suitable for travel, but the huge screen is really a delight to use.
I've largely ignored Macs here, and I shouldn't – Macintosh notebooks are becoming more popular all the time. I've also ignored ruggedized computers used in industrial and military applications, but a whole bunch of these are also on the market. They tend to cost several times as much as their commercial counterparts, but they may be worth the extra cost if you work in adverse environments or are otherwise really tough on your gear.
Finally, mobile computer technology has become relatively stable in recent years. Two big innovations on the horizon are the use of solid-state or hybrid solid-state/rotating memories, which could improve both responsiveness and ruggedness to some degree, and the availability of ExpressCard slots, which are replacing PC Card slots on many notebooks and offer performance of 2.5 Gbps.
Next time we'll continue with further examination of form factors, but with handhelds in mind.
About the author: Craig Mathias is a principal with Farpoint Group, an advisory firm based in Ashland, Mass., specializing in wireless networking and mobile computing. The firm works with manufacturers, enterprises, carriers, government, and the financial community on all aspects of wireless and mobile. He can be reached at email@example.com.