Just what is Windows RT, anyway? (FAQ)

Microsoft has a supersecret announcement coming on Monday, and it may well be a tablet running Windows RT. Here's what we know so far about the mostly Metro, ARM-powered variation of Windows 8.

What in the world is Windows RT?
Coming off of our previous coverage, you may have heard about Windows 8 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 limited Windows 8 version to run on ARM processors called Windows RT (WinRT).

What does "RT" stand for?

"RT" is an abbreviation of Windows Runtime, the technical term for the engine that powers the new Metro apps. It's not the first Windows Runtime. The term "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.

What is Metro?

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.

So, what is WinRT?

Basically, WinRT is 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 WinRT?

There are several notable differences, and they could cause WinRT 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:

WinRT will work only on ARM-powered devices

WinRT 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

WinRT will come with device encryption

Neither old nor new x86/x64 programs will work on WinRT

What kind of apps can WinRT run?

The focus of Metro apps will be on Internet connectivity, cloud synchronization, and responsiveness. If it works in Windows 8 Metro, it will work on WinRT. 

Will I be able to update an old ARM-powered device with WinRT?

No. At this point, WinRT will be available only pre-installed. That's not expected to change, either.

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.

Are there any other drawbacks to WinRT?

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 WinRT 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 WinRT the way Apple has locked down iOS.

The OEM license for WinRT is expected to be in the $80 range, so it's likely that WinRT 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 WinRT tablet. That doesn't bode well for manufacturer confidence.

There doesn't seem to be a way to visually distinguish a WinRT 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.