The conventional way of thinking about the electronics market is to say that Microsoft Windows and Intel x86 processors dominate the desktop and laptop market but haven't done well in the growing mobile devices market.
Mary Meeker and Horace Dediu propose another way of looking at things in this chart that can be found as the 24th slide on her 2012 Internet Trends presentation. The game here is to say that the Galaxy Tab and the iPhone should all be looked at as computing devices, and we should see that the explosion of Android and iOS devices (typically powered by ARM chips) is leading to a catastrophic erosion of the Wintel market share.
I think neither of those perspectives captures the whole truth. My sense as someone who uses all these devices is that there's some phone-tablet substitutability and also some tablet-laptop substitutability but very little phone-laptop substitutability. That makes it hard to know how to characterize the scope of the market.