In a blog post, Microsoft executive Charlie Kindel wrote that "previous Windows mobile applications will not run on Windows Phone 7 Series."
Kindel, Partner Group Program Manager for the Windows Phone Application Platform & Developer Experience, stated this was because Microsoft "had to change how phone apps were written."
He wrote: "To be clear, we will continue to work with our partners to deliver new devices based on Windows Mobile 6.5 and will support those products for many years to come, so it’s not as though one line ends as soon as the other begins."
Mark Tauschek, lead analyst with London, Ont.-based Info-Tech Research Group, was not surprised.
He said the Windows Mobile operating system was based on Windows CE and Microsoft had no choice but to build a new operating system for wireless phones “from the ground up” in order to better compete with Google Inc.’s Android operating system and Apple Inc.’s iPhones.
“It’s an extraordinarily painful thing for Microsoft to do,” Tauschek said. “Believe me they don’t want to do this. They really had to ditch the legacy stuff and in order to ditch the legacy stuff they had to build Windows Phone 7 from the ground up. People will squawk a little bit about it but it’s not by any means unusual.”
Windows Phone 7, unveiled last month at Mobile World Congress in Barcelona, will include customizable “live tiles” that can be updated automatically.
These tiles would show contact information for people with whom the user regularly communicates. Windows Phone 7 also has a "hub" that lets users take notes and synchronize documents with their PCs.
Microsoft is also designing Windows Phone 7 to run games and with an on-screen QWERTY keyboard.
The changes are not groundbreaking, Tauschek said, but he compared it to some of the changes when Microsoft announced the Windows 7 operating system for PCs, which does not run some applications written for Internet Explorer 6 browser.
“Believe me there are a ton of Web applications in enterprises running on Internet Explorer 6,” he said. “It’s the only reason the legacy browser has 12 pc market share.”
Though Microsoft had to make a clean break from Windows Mobile 6.5 when developing Windows Phone 7, the lack of backwards compatibility will be a double-edged sword.
“At one point in next five years, (Microsoft) will say, ‘We just lost in the mobile space,’” Tauschek said. “It’s really going to hurt them but they had no choice.”