Microsoft's next Windows 10 Mobile test build on track to support majority of Windows Phones

Microsoft's next Windows 10 Mobile test build, expected around early April, will support a lot more Windows Phone test devices than the first build did.
Written by Mary Jo Foley, Senior Contributing Editor

Microsoft's Operating Systems Group team has added code to the next test build of Windows 10 Mobile that will allow that release to work on the majority of Windows Phones.

When Microsoft released the first test build of Windows 10 Mobile in February 2015, it was built to run only on a handful of Lumia devices, specifically, Lumia 630, 635, 636, 638, 730 and 830 phones. Microsoft execs attributed the small number of initially supported devices to the "very tight OS partitions" that left insufficient room for the installation process to update the OS in place.

But the second test build, which may not be available until the first week of April or so, will support the majority of existing Windows Phones. Microsoft officials went public with the list of Windows Phones that will likely be able to run the next test build in a March 27 blog post.

The initial list, which isn't 100 percent locked, according to the post, includes:

  • Lumia 1020
  • Lumia 1320
  • Lumia 1520
  • Lumia 520
  • Lumia 525
  • Lumia 526
  • Lumia 530
  • Lumia 530 Dual SIM
  • Lumia 535
  • Lumia 620
  • Lumia 625
  • Lumia 630
  • Lumia 630 Dual SIM
  • Lumia 635
  • Lumia 636
  • Lumia 638
  • Lumia 720
  • Lumia 730
  • Lumia 730 Dual SIM
  • Lumia 735
  • Lumia 810
  • Lumia 820
  • Lumia 822
  • Lumia 830
  • Lumia 920
  • Lumia 925
  • Lumia 928
  • Lumia ICON
  • Microsoft Lumia 430
  • Microsoft Lumia 435
  • Microsoft Lumia 435 Dual SIM
  • Microsoft Lumia 435 Dual SIM DTV
  • Microsoft Lumia 532
  • Microsoft Lumia 532 Dual SIM
  • Microsoft Lumia 640 Dual SIM
  • Microsoft Lumia 535 Dual SIM

(Several have noticed that the Lumia 930 isn't on this list. Update: There is some bug unique to the 930 that Microsoft is still trying to track down.)

Head of Microsoft's Windows Insider program Gabe Aul said that the required partition stitching feature code required to support these phones came into Microsoft's main code branch late last week. Last week, Microsoft tested that code on individual devices inside the company. Aul also said the next test build will include support for phones that didn't have China Mobile Operator support in the first test build.

"I cannot guarantee a date for a new build. What I CAN tell you is that we feel great here about the partition stitching code and current builds, but we likely still have at least one more week of engineering to do to ensure we get a great build for the expanded list of devices," Aul said.

There's no mention in Aul's post about when Microsoft will support small ARM- and Intel-based tablets with a Windows 10 Mobile test build. Windows 10 Mobile is the version of Windows 10 that is built to run on both phones and small (under eight-inch) tablets. One Windows tester noted there's currently no Visual Studio emulator for Windows 10 Mobile for Intel tablets. I'm not sure why it's not there (change in Microsoft plans or just not ready yet, maybe?).

Microsoft officials have said Windows 10 will launch "this summer." The first test build of Windows 10 Mobile didn't yet include the new "Spartan" browser that will ship as the only browser on Windows 10 Mobile devices.

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