Gold noted that optimizing for battery life on a smartphone versus optimizing for raw performance on a PC are quite divergent design points. While tablets and PCs are aligned more closely in components, there are distinct differences that warrant "tuning" the OS to the platform.
Gold said the Microsoft operating systems will move closer together over time, as will Google's Chrome OS with Android. However, "I don't see them ever fully merging, since that would sub-optimize the various requirements and probably make the result less attractive for users and manufacturers," he said.
Patrick Moorhead, an analyst at Moor Insights & Strategy, said that what Microsoft needs more than a unified OS is a unified development environment, which he expects will emerge in the next 18 months. "A unified Windows OS risks being a light PC OS and too heavy for phones," he said.
Rob Enderle, an analyst at Enderle Group, said that with software virtualization, Microsoft potentially doesn't have to create a "one-size-fits all" OS. However, he said Microsoft seems to be on a path over the next five years of using an embedded core for all platforms where developers would add user interfaces that work best for a certain screen size.
Insights from Windows developers
Whether Microsoft's operating systems fully come together was the subject of some debate among four developers who were interviewed separately by phone and email. However, all four support a fuller common development environment across all the platforms.
James Vertisan, CEO of Vertisan Inc., a maker of golf-related apps, said it is "imperative to merge" Windows, Windows RT and Windows Phone, and he commended Microsoft for already offering a shared code base between the OSs.
He estimated about 75% of the source code is already in common. "There are things we can't re-use across platforms, such as the layout of a particular view, but everything else that lives beneath is synonymous," Vertisan said. A phone is primarily navigated vertically and displayed at 800 x 600 pixels, while a tablet, displayed at 1366 x 768, is navigated primarily horizontally.
Vertisan makes the Shotly golf app for Windows Phone 7 and 8 and iOS, and is about to release a social networking app for golfers called Golfly, which is being showcased on Windows 8 devices. It will allow users with a tablet to remotely follow someone playing golf, picking up their inputs on shots from a smartphone running Shotly, with the ability to interact and send text messages, such as "Great shot!" Both Shotly and Golfly are free apps, although in-app purchasing and upgrades are available.
Vertisan sees a chance for Windows Phone and Windows tablets to grow in market share, partly because of the ease of development of apps. He said he and other developers have seen efficiencies in using Microsoft's C# and XAML programming languages in building apps for Windows.
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