The PCs were in existence since long while the mobile platforms like iOS and Android have come into existence only recently and they have experienced a sudden meteoric rise. The personal computers started to evolve in the mid 70s and they were given the name PC indicating the presence of Windows operating system.
The mobile platforms like Android and iOS started to appear quite late but they started to show a massive growth since then. Asymco's Horace Dedieu has put all the estimates together and concludes that Android will pass the PC sales this year and then overtake the iOS sales in 2013.
The figures taken for the estimate were obtained from Gartner but then Dedieu has made all the predictions. He claims himself as an independent analyst and his estimates were found to be quite accurate. These figures are the evidence that show the presence of a computing world.
The rise of the mobile phone sales should not be such a huge surprise as the growth was quite large in the past decade. But this growth was over-driven with the adoption of Android and iOS. Within few years, the PC sales figures will start declining as the mobile phones are more prolific and capable.