Each week Ross Rubin contributes Switched On, a column about consumer technology.

The iPad, launched in 2010, kicked off the post-PC era. The combination of a multitouch display and keyboard-less design enabled mobile computing in a way not done before. On the other hand, maybe the IBM Simon, launched in 1992, kicked off the post-PC era. Widely considered to be the first smartphone, it enabled mobile computing in a way that was not done before. Then again, maybe the Osborne I, launched in 1981, marked the beginning of the post-PC era. After all, it was widely considered to be the first portable computer, enabling mobile computing in a way that was not done before.

Or maybe it was the Psion Organizer II, often considered to be the first PDA, or the Epson HX-20, recognized as the first laptop, or the Grid Compass 1100, BlackBerry 850 or any number of other pioneering devices. Once upon a time, a PC was thought of only as a desk-bound box with a keyboard and monitor (and, later, a mouse). Anything that has broken that convention has ushered in a post-"PC" era.

These days, there's lots of debate about whether iPads should be considered PCs for the purpose of calculating market share. The challenge is that previously, PCs primarily existed in two form factors -- desktop and notebook -- and generally under an OS duopoly (at least in the consumer market) of Windows and Mac OS. One of the major points in favor of counting iPads is that there are Windows-based slates on the market and so it is not fair to count those and omit iPads or tablets running Android or other operating systems. This year, the distinction will blur even further as Windows 8 invades slates. Looking beyond 2012, today's quasi Windows competitors, Android and iOS, will grow only more capable.

PC apps used to be confined to a handful of tasks.

On the other hand, including slates leads to a slippery slope. Is the Amazon Kindle Fire a PC? And if so, why aren't iPod touches or smartphones? With a Bluetooth keyboard and a monitor connected via HDMI, many smartphones are capable of handling everything a desktop PC did years ago, and more. One could also make cases for smart TVs; the WIMM One and other connected watches; PCs on a USB stick" like the FXI Cotton Candy; and emerging product categories such as as plug computers (think the TonidoPlug). Before Sony locked out the ability to install Linux on PlayStation 3, they were used to build supercomputers.

And it's not just the hardware that has become more dynamic. PC apps used to be confined to a handful of tasks: productivity, design, internet access and games. These days, a range of devices from brownout-inducing custom PC gaming rigs to battery-sipping smartphones play a more central role in our lives, helping us to communicate, shop and enjoy limitless content options, and increasingly, do so with ease -- largely thanks to more natural input methods such as touch, speech and gestures.

As computing has infiltrated what were once dumb screens, the meaning of a PC is starting to dilute to the point where it's almost meaningless. Put another way, there is no "post-PC era"; the PC merely marked the start of the consumer computing era. Indeed, even before the iPad came on the scene, there was no real uniform "PC" market with companies like Toshiba, for example, eschewing desktops. This makes Toshiba's overall PC share seem relatively low, but its notebook share is comparatively high.

There is no perfect answer. For now, though, a better way to think about what has characterized the PC market is to focus more on form factors. Form factors, more than input methods, connectors or competitive operating systems, define the usage scenarios and therefore the consideration set of a computing product category.

What about combining desktops and notebooks to determine, say, Windows' overall share versus OS X's? Instead, one could determine an operating system's total addressable share by considering competition in all the form factors in which the OS participates. For example, Windows 8's share could be determined across its competitors in desktops, notebooks and tablets. Android's could be determined across smartphones, tablets and TVs. At some point, one could create a huge roll-up of smart consumer devices share with a defensible but not unassailable definition such as "has access to user-installable apps."

Much of what determines a form factor, though, is the display, and this may well break down as technologies such as scrollable displays and micro-projection redefine the opportunity for a large display in a pocket-sized device. That, combined with emerging input and interface technologies that could finally kill off the keyboard and mouse, could create a blurring of categories that will make quibbling over PC classification seem trivial. The resulting debate should keep us all arguing until those with intelligence-augmented cortex implants realize how silly it all was.

Ross Rubin (@rossrubin) is executive director and principal analyst of the NPD Connected Intelligence service at The NPD Group. Views expressed in Switched On are his own.


Switched On: Think form factors, not PCs