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Just what is Windows RT, anyway? (FAQ)

The "lite" version of Windows 8 known as Windows RT remains the biggest unknown out of the myriad of changes coming to Microsoft's operating system. Here's our guide to what Windows RT is, how it's different from Windows 8 and WinRT, and what it all means.

Seth Rosenblatt Former Senior Writer / News
Senior writer Seth Rosenblatt covered Google and security for CNET News, with occasional forays into tech and pop culture. Formerly a CNET Reviews senior editor for software, he has written about nearly every category of software and app available.
Seth Rosenblatt
5 min read
First Look
Watch this: Windows 8 leads with tiles, apps, sync -- and a learning curve, too

Note: This story was originally published on June 15, 2012. It was republished on October 12, 2012 with additional details about Windows RT.

Coming off of our previous coverage, you may have heard about Windows 8 (read CNET's review) and Windows RT as being different. While Microsoft has made a point of cutting down on the number of Windows 8 versions available when compared with previous Windows releases, the company is also making a feature-limited Windows 8 version to run on ARM processors called Windows RT. Windows RT is more like Microsoft's attempt to do a Windows version of Apple's locked-down iOS than anything else.

Microsoft Corp. CEO Steve Ballmer introduces the all-new Surface tablet during the company's mystery event in Los Angeles, Calif. Josh Lowensohn/CNET

What does "RT" stand for?
As with Windows NT, Microsoft has yet to clarify what "RT" actually means. Why on Earth Microsoft decided to name the ARM-powered version of Windows so ridiculously similar to the abbreviation for Windows Runtime, WinRT, is beyond the abilities of mere mortals to decipher.

Wait, what? Windows RT and WinRT aren't the same thing?
The short answer is, "Nope."

The long answer is, well, longer. Windows Runtime, also referred to as WinRT, runs on both standard Windows 8 and Windows RT. Runtime is the technical term for the engine that powers the new Metro apps. It's not the first Windows Runtime. "Runtime" refers to the collection of application programming interfaces (APIs) that allow developers to write software that can interact with the hardware and each other.

Windows RT is simply a name that Microsoft has given to Windows 8 on ARM. You wouldn't be entirely off base to think of it as "Windows Lite," given its restrictions and differences from standard Windows 8, which runs both Metro and Desktop modes.

What is Metro?
For one thing, Microsoft doesn't want you to call the new interface Metro anymore, but it may be too late for that. Naming aside, Metro is the new user interface for Windows 8. Instead of icons, there are "tiles" that can surface information from the app in real time, and it's powered by WinRT.

So, what is WinRT?
Basically, WinRT is the underpinnings of the Metro side of Windows 8. But it does more than implement the Metro interface, it also simplifies much of the programming for Windows developers. Coding for Metro is significantly easier than writing a program for Windows 7 and earlier. This is important for Microsoft because it can now point to Windows 8 as an attractive place for developers to ply their trade.

What's the difference between Windows 8 and Windows RT?

There are several notable differences, and they could cause Windows RT to fail while Windows 8 succeeds. Microsoft has produced a chart of the differences between Windows 8 and Window RT, but here are the highlights:

  • Windows RT will work only on ARM-powered devices
  • Windows RT will have a Desktop mode, but it will be restricted to pre-installed, Microsoft-produced software. This will include touch-optimized versions of Microsoft Word, Excel, PowerPoint, and OneNote as the new Microsoft Office
  • Windows RT will come with device encryption
  • Neither old nor new x86/x64 programs will work on Windows RT

The Lenovo IdeaPad Yoga 11

What devices will run Windows RT?
Manufacturers are being extremely cautious about embracing Windows RT. Of all the changes in Windows 8, the biggest unknown is predicting how people will react to its "Windows 8 Lite" approach. Here's CNET's complete list of Windows 8 computers and tablets, but we've pulled out the Windows RT devices below:

  • Microsoft Surface RT: Microsoft is making a big splash with its first in-house designed computer hardware ever. There will be two versions of the Surface available, one running Windows RT and the other running standard Windows 8. You can buy the Windows RT version, called Surface RT, when the operating system and hardware from Microsoft's manufacturing partners is made available to the general public on October 26.
  • Dell XPS 10 Tablet hybrid: A smaller form factor of the XPS 12, which will be running full-fledged Windows 8. The unique design is resurrected and renamed from the Dell Duo line.
  • Lenovo IdeaPad Yoga 11: Like the XPS 10, the IdeaPad Yoga comes in two sizes. The smaller one will run Windows RT, while the larger gets full-fledged Windows 8. Also like the XPS 10, the Yoga brand features a unique design where the screen can bend back on itself. No word from Lenovo on whether it will help you with your Sun Salutation.
  • Samsung Ativ Tab: Samsung's no stranger to tablets, thanks to Android. Ativ Tab is the most Android-looking of the Windows RT hardware that's been announced so far.
  • What kind of apps can Windows RT run?
    The focus of Metro apps will be on Internet connectivity, cloud synchronization, and responsiveness. If it works in Windows 8 Metro and does not open in Desktop mode, it will work on Windows RT.

    Microsoft may be getting into this market, but Dell isn't deterred. It announced its XPS 10 Windows RT tablet at the IFA consumer-electronics show in Berlin. It's got a detachable keyboard.
    Microsoft may be getting into this market, but Dell isn't deterred. It announced its XPS 10 Windows RT tablet at the IFA consumer-electronics show in Berlin. It's got a detachable keyboard. Stephen Shankland/CNET

    Will I be able to update an old ARM-powered device with Windows RT?
    No. At this point, Windows RT will be available only pre-installed. That's not expected to change, either.

    Full coverage: Windows 8/RT

    What's the benefit of ARM?
    ARM processors power virtually all iOS, Android, and other mobile devices on the market. ARM has gained so much traction in large part because of its better battery management. Malware designed to run on current Windows computers generally won't work on ARM's chips. ARM could be a huge boon to Windows, if only Microsoft can convince people that Windows RT is worthwhile.

    Are there any other drawbacks to Windows RT?
    There are a couple that stand out so far that we haven't mentioned yet.

    • There are certain core APIs that Microsoft is restricting access to in Windows RT that are available in full Windows 8. This has caused much consternation among browser vendors and has raised fears that Microsoft is attempting to cut off browser innovation by locking down Windows RT the way Apple has locked down iOS.
    • The OEM license for Windows RT is expected to be in the $80 range, so it's likely that Windows RT devices will be notably more expensive than their Android-powered counterparts.
    • While we've seen some hardware specs for standard Windows 8 devices, including tablets, we haven't seen any confirmed specs for a single Windows RT tablet. That doesn't bode well for manufacturer confidence.
    • There doesn't seem to be a way to visually distinguish a Windows RT tablet from a Windows 8 tablet, which could lead to buyer confusion, to put it mildly.
    • Windows RT remains the biggest gamble that Microsoft is taking with Windows 8, because it's cutting itself off from legacy Windows. Sure, there's a free version of Office included, and that may draw some people in on its own. There's scant evidence from consumers or manufacturers that they're interested in this version of Windows 8, but it could also position Microsoft for future growth in a way that limiting itself to Intel chips can't.

      Correction, Friday, June 15, 2012, at 11:50 p.m. PDT: The original version of this FAQ conflated the terms "Windows RT" and "WinRT." They have since been clarified.