Despite the trend toward mobility, desktop PCs are still going strong. But they too are changing rapidly. All-in-one systems are becoming a larger part of the mix, and manufacturers are experimenting with other variations. The , which will ship later this year, offers a multitouch display that can lie completely horizontal; you might think of it as a big brother to Microsoft’s newly announced Surface tablets. Ultrasmall units are also becoming popular in offices, homes, and industrial settings. Inspired by the interest in the Raspberry Pi (the tiny, supercheap PC-like device built around a system-on-chip and running Linux), Intel is building its NUC (Next Unit of Computing), which carries an Ivy Bridge-class dual-core CPU in a tiny, 4-inch-square case smaller than the Apple TV.

Even the most hard-core PC users, including serious gamers and performance enthusiasts, are looking beyond the familiar PC box. The , for instance, packs fairly serious PC gaming muscle into an Xbox-size chassis.

All of this experimentation forces us to reexamine what a personal computer is, and what it could become.