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Windows Phone 7: What's behind chassis doors 1, 2 and 3?

It sounds like there are three different chassis specs to which mobile developers interested in building Windows Phone 7 Series devices will be adhering. There aren't many public details on what these specs include, but thanks to a couple of Microsoft podcasters, here's a little more information.
Written by Mary Jo Foley, Senior Contributing Editor

Microsoft execs have been explaining and re-explaining what the company's decision to tighten its mobile requirements will mean for both its phone makers and customers when the Windows Phone 7 Series phones start shipping late this year. But one set of details about which they've offered scant public information is specs.

Thanks to a reader tip, however, I listened to the "Frankly Speaking" podcast (dated February 20).  About 3.45 minutes in, the Microsoft Australia Developer Evangelist hosts (Michael Kordahi and Andrew Coates) start talking about Microsoft's decision to cut back the unwieldy number of supported Windows Phone chassis to three with Windows Phone 7.

Chassis 1 is for PC makers developing "big touch screen" phones, the hosts said. These will be touch-only devices, with 1 GHz processor (hello, Snapdragon!) and a dedicated graphics processor, the Frankly Speaking guys said. These are the phones that will be out first at launch this holiday season.

Chassis 2-compliant phones will support real sliding keyboards plus touch, the podcasters claimed. They said these would be more Palm-Treo-like. There also will be Chassis 3 phones, about which the pair didn't have any details. One of the hosts (I couldn't tell which) said he expected Chassis 3 phones might be candy bar phones. The pair didn't say when Chassis 2 and 3 phones might ship.

It's been rumored for over a year that Microsoft would be locking down its phone ecosystem so that fewer partners were required to adhere to more rigorous specifications. In fact, all those rumors about Microsoft making its own Windows Mobile 7 phone were more likely than not, actually rumors about the evolving set of chassis specs that Microsoft was creating for its Windows Phone partners.

Last year, I posted a copy of a spec list for Windows Mobile 7 Chassis 1. At the time, I was led to believe this was the chassis spec for the forthcoming Microsoft Pink phones, but now I don't think that's the case. (And I'm still unclear what the operating system in those Pink phones will be.) These days, I'm wondering how close that WM7 Chassis 1 spec is to the current spec? At that time, I also had heard talk of Windows Mobile 7 Chassis 2 and 3, but never was able to get more information on those specs.

I've asked Microsoft for more information about its Windows Phone 7 chassis specs, but I'm not holding my breath.

(Update on February 24: The official (non)statement, via a spokesman: "Microsoft does not have any further comments on the information our Australian subsidiary shared recently.  MIX is where we will share our next update on our mobile platform.")

In other Windows Phone 7 news, it looks like Microsoft might be sharing more details about its developer tools and strategy for the platform slightly ahead of the Mix 10 conference. MobileTechWorld has information about some of the mobile-dev-centric sessions Microsoft is planning for the Game Developers Conference, which is slated for the week before Mix 10. The write-ups for these sessions say they will cover "Windows Phone" gaming development (not Windows Phone 7 gaming development), but I'm betting the latter topic will be part of what's discussed. (One of my sources told me recently that games developed using the XNA gaming framework will be targeting Windows Phone OS 7.1 devices, not the first-generation 7.0 ones. Guess we'll find out if that's true soon....)

As I noted last week, it sounds as though Microsoft is planning to make Silverlight and XNA its primary Windows Phone 7 development platforms, introducing new design and development tools to support programmers interested in writing applications for its Windows Phone 7 and Zune HD platforms.

There's one more thing: After listening to the aforementioned "Frankly Speaking" podcast, it finally sunk in that the Windows Phone 7 user interface, while borrowing heavily from the Zune HD UI, actually takes its earliest cues from Media Center. The hosts noted that the "Metro" user interface on the new phones came out of the work Microsoft pioneered with Media Center.

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