Designing For PurposeDesigning For Purpose

Other design examples also illustrate the importance of "design for purpose":

The RIM BlackBerry excels at the purpose of wireless E-mail. A combination of device ergonomics, server architecture, and software design creates an excellent fit, engendering tremendous loyalty in users for whom that purpose is paramount.

Palm has studied patterns of use in designing its devices and software, and this is reflected in the compact design of the Tungsten T device. Built on the observation that PIM users look up information far more frequently than they enter it, the Graffiti input area is concealed under a sliding cover until needed, reducing the "footprint" of the device. The Tungsten W, on the other hand, targeted at wireless E-mail users, is designed around quite different use patterns.

In the Java 2 Micro Edition world, the Mobile Information Device Profile (MIDP) has achieved rapid initial success by focusing on the requirements of the limited-range capabilities of constrained phones. Personal Java (soon to be succeeded by Personal Profile) has achieved less traction, in part because it targets a broad range of devices and there's no obvious design center.

Nokia recently announced a game-centric phone whose physical design is optimized for game-playing (in contrast to existing phones that awkwardly co-opt navigation buttons for game functions).

Communicator devices that combine a full-function PDA and a phone have so far proven disappointing in the market. Most designs, to date, are less than satisfactory in either role.

The lessons from the market seem to be that design for purpose can be manifested in the form of a specific intended role, form factor, input style, or software (or indeed any combination of these), depending on whether the market is horizontal, vertical, or consumer.

Buyers concerned with the viability of a vendor or the popularity of a platform can use the fitness-for-purpose test as a powerful guide. At the low end of the device scale, successful platforms tend to be tightly constrained and fitted to an intended purpose, and in general the smaller a device, the more users seem to treat it as a tool that must fit its purpose rather than as a platform to be molded to various tasks.

At the high end--certainly for laptops and above, and probably including tablets--users expect a general-purpose, versatile platform akin to the familiar PC and purpose-specific appliances fail.

One fascinating question that remains to be answered is where the crossover occurs. Somewhere between the successful high-end PDAs of today such as the Hewlett-Packard iPAQ Pocket PC and the smallest, lightest laptops lies a gray area where it is far from clear whether the need to design for purpose or the desire for versatility dominates. Perhaps no device can satisfy both requirements. Until the answer becomes clearer, any new designs venture into that design space at their own risk, and users must proceed with great caution.

Carl Zetie is VP of research at Giga Information Group.

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