As we move into the era of pervasive computing, in which PCs will be complemented by a diverse assortment of information appliances, one of the toughest design decisions is determining how many functions to integrate into one product. The issues are surprisingly complex.
The PC is the ultimate example of a multifunction, general-purpose device, capable of a wide range of tasks. At the other end of the spectrum, an MP3 player does just one thing. By focusing on one capability, its size can be reduced to a minimum, and its controls and interface are designed especially for that function.
These two examples are clear-cut; few others are. Consider the PDA. You can treat a PDA as a device with a small set of fixed functions: calendar, contact list, and notes. But a PDA can do many other things, from playing games to viewing photo albums. And it can play MP3 files.
Does it make sense to keep adding functions to a handheld device? It depends on whether you can perform those functions effectively within the physical constraints of the device. Once you've invested in a device with a processor, memory, and an LCDand go to the trouble of carrying it with youit makes sense to give it additional functions that naturally fit.
Just how far to take this expandability remains a question. Hand spring has demonstrated a Visor handheld with a cell-phone add-on, and Microsoft has shown a similar product based on its Pocket PC platform. Does this make sense? In one way, it does; after all, you often need to enter into your cell phone the number you look up on your handheld.
It's unclear, however, just how popular this combination will be. The phone adds significant cost, so it isn't the same as just adding another program. Furthermore, the physical interfaces are fundamentally different. A PDA needs a much larger screen than a phone, and a phone needs a microphone and a speaker. It's no coincidence cell phones and PDAs are shaped differently.
By connecting a headset to the PDA, its physical shape can be made usable as a phone. But it still won't fit as easily in a pocket, and the headset can be awkward. The best solution is to have a separate phone and PDA that communicate and act together, but that you can use separately. Bluetooth will make such an approach practical.
Another important example is the game console. So far, game consoles have been mostly special-purpose devices. This may change, however, now that they've become more powerful. If the TV cable connected to the console provides a high-speed Internet connection as well, many other functions become appealing. The console could become the living-room computer, taking on functions such as playing movies, browsing the Web, and viewing photo albums. Sony has this sort of evolution in mind for its PlayStation2, and Microsoft is creating the X-Box because it can't afford to abdicate the living room to Sony.
All sorts of odd combinations are showing up: cell phones that include MP3 players, cell phones that are also digital cameras, digital cameras that play MP3s and can access the Web, LCD monitors that are also televisions, and microwave ovens and refrigerators with Web terminals integrated into their doors.
Which of these combinations make sense? It depends on an assortment of factors. If one of the combined functions is handicapped, it's not a good choice. If the two functions need different input and output devices, the choice is questionable, but not necessarily wrong.
One important factor is the sharing of expensive resources. Microprocessors have become inexpensive enough that it's often not necessary to share them, but the components surrounding them can be expensive. Displays and storage, in particular, are now the precious resources. Thus, the LCD monitor that's also a television makes sense because it delivers two functions from one expensive panel, but you probably want your TV and computer in different places.
It dices, it slices, it chops
A key factor that will push products toward multiple functions is the universal nature of digital data. In the analog world, a newspaper, a letter, a calendar, a record player, a videotape recorder, a television, a radio, and a photo album were fundamentally different things. In the digital world, everything is bits, and the same device can serve all these functions. Yet there remains merit in focused, limited-function devices, which tend to be less expensive, easier to use, and better optimized for a given function. Designersand consumerswill continue to struggle to find the optimum balance.