The Internet began boisterously buzzing last week that Microsoft will unveil its own tablet later today, perhaps one powered by Windows RT, the offshoot of Windows 8.
On Monday, the speculation grew even more adamant, with the New York Times claiming that Microsoft sources told it that the company will indeed introduce its own tablet, and that the device would run Windows RT.
While Microsoft has aggressively touted Windows 8 with scores of blog posts spelling out often picayune details of the upcoming operating system, the company has been relatively quiet about Windows RT, the all-mobile OS destined for tablets. How is Windows RT different from its better-known cousin? Why did Microsoft create two versions when Windows 8 also boasts some of the same features and relies, at least in part, on the same design motif and user interface (UI)?
Questions, questions, questions.
And because there's a growing chance Microsoft will make a landmark move -- it's never directly competed with its PC- or tablet-making partners -- we have some answers.
Where do I buy Windows RT? You don't. Not separately, anyway, as Windows has been sold for decades. Windows RT is OEM-only -- OEM, for "original equipment manufacturer" is simply a computer maker, like Dell or Hewlett-Packard or Lenovo -- and the OS can't be purchased by individuals or Microsoft's corporate customers.
Instead, it is pre-installed on devices, most likely tablets, although Microsoft has been trumpeting a claim that at some point, low-cost, power-miserly notebooks will also run the OS.
The rumored tablet that Microsoft is to unveil later today would run Windows RT, making Microsoft its own OEM for the first time ever for a computer or computer-like device.
So Windows RT is the same as Windows 8? No, it's not. They're two separate lines of Windows, and to delve into family history, cousins at best -- maybe once removed.
Think of it this way: Windows RT is to Windows 8 as Apple's iOS is to OS X. The two within each pair clearly have a shared history, some shared code, but are distinct operating systems designed for different classes of devices, and run on completely different, and incompatible, processor platforms.
Both OS X and Windows 8 run on Intel's x86/64 processor architecture, while iOS and Windows RT work only on devices with ARM-licensed CPUs.
So I'm guessing that apps designed for Windows 8 -- or older version of Windows -- won't run in Windows RT. You are correct. Programs designed for Windows 8, the operating system that runs on devices powered by Intel's x86/64 processors, will not only not run on Windows RT, they're not even allowed to try. With a few exceptions..., because there are always exceptions.
Those include a handful of Microsoft-made applications, most notably Office and Internet Explorer 10 (IE10), that run on a "classic" desktop -- a mode and user interface (UI) within Windows RT that Microsoft included largely so it could bundle four Office programs -- Word, Excel, PowerPoint and OneNote -- with the operating system.
Microsoft's told developers that it they want to sell their wares for Windows RT, they need to redesign -- and recode them -- from the ground up to make "Metro" editions of their software.
Okay, you're starting to lose me, but I'll bite. What's Metro? Although technically the name of the design language Microsoft's applied to a tile- and typography based look-and-feel, it's used most often to label the resulting UI and the apps that run in it. With a few exceptions -- Office, IE10 and a few other Microsoft programs (see above) -- all software that runs on Windows RT are Metro apps.
The name "Metro," by the way, is a reference to its inspiration: public transportation signage like that used in airports, subway systems and other locales.
But I keep hearing about Metro on Windows 8. What gives? Traditional Windows software won't run on Windows RT, but Metro apps run on both RT and Windows 8.
Yeah, it's confusing.
Windows 8 has two "runtimes," or collections of APIs (application programming interfaces), that support both Win32 programs -- the software that's run on earlier editions -- and Metro apps.
Windows RT, on the other hand, boasts just one runtime -- the name of the OS comes from the phrase "Windows Runtime" -- and so runs only Metro apps.
What apps will be included with Windows RT? Microsoft's home-grown Metro apps -- core programs for accessing email, photos, maps and so on -- as well as the four Office apps and IE10.
Microsoft has even said that any e-reading app created by its new partner Barnes & Noble will be distributed via the Windows Store, the sole outlet for Windows RT software.
Although Microsoft hasn't confirmed one way or the other -- it has left tons of questions unanswered at this point -- it appears that OEMs will not be able to pre-install apps on Windows RT devices, as they do now on Windows 7 PCs.
While critics deride the practice as "crapware" and "bloatware," OEMs reportedly make significant revenue from software vendors, who pay the computer makers a percentage of what they receive when customers upgrade from free trial versions to fully-functional editions.
Where will I get Windows RT apps? From the Windows Store. That's the name of Microsoft's app store for Windows RT, and the sole source of Metro apps for Windows 8, too.
Windows Store opened earlier this year, but it remains in beta. Until it officially launches alongside Windows 8 and/or Windows RT, all apps must be free. At that time, however, developers will be able to add for-a-fee versions of their Metro software.
Why did Microsoft create Windows RT? One-word answer: Apple.
ARM processors -- made by multiple chip companies, all of which license the architecture from U.K.-based ARM Holdings before putting their own spins on the chip -- power the vast majority of mobile devices, smartphones and tablets, including the iPad and the iPhone.
ARM CPUs sip power at much lower rates than those from Intel, and so squeeze many more hours from a battery, a key to tablet -- or smartphone -- success.
Now two years behind Apple, which has run through three iterations of its iPad, Microsoft needed a way into the tablet market. Hence Windows RT, which the company first called Windows on ARM, or WOA for short.
Windows 8 will show up on tablets of some kind, too, but those will run on Intel processors, which can't yet match ARM in the low-power, long-battery-life departments. Without a pure-play on tablets, Microsoft risked being left out of a fast-growing market that has already had an impact on traditional PC sales, a major Microsoft source of revenue through sales of Windows licenses.
When will we see Windows RT When devices ship. Unlike Windows 8, which Microsoft has been aggressively promoting with a series of free public previews, Windows RT won't show itself until tablets powered by the operating system appear.
Microsoft has yet to disclose ship dates for Windows 8 or the debut of Windows RT devices. But it has said that the former's goal is to launch in time for the 2012 holidays and that Windows RT is "on our schedule," whatever that is.
If it does introduce a Windows RT tablet today, Microsoft may also define a launch timetable for the device and the operating system.
Will all Windows RT tablets be alike? No. While Microsoft has set out certification requirements for Windows RT devices, it has not adopted Apple's strategy of making and selling a one-size-fits-all tablet.
For example, to be Windows 8/Windows RT certified -- in other words to display a Windows logo -- tablets must have five (no more, no less) buttons, including one called "Windows Key" that serves the same purpose as the iPad's Home button.
Windows RT tablets must also have a display with at least a resolution of 1366-by-768 pixels, which then packs more pixels than the original iPad and the iPad 2 (1024-by-768-pixels), but far fewer than the newest iPad's "Retina" display.
But Windows RT hardware can offer resolutions higher than the minimum, of course.
If you have time on your hands and the inclination, you can peruse the requirements by grabbing the "Windows 8 System Requirements" PDF from this page (click the first "Download" button). The tablet section starts at p. 86.
Why is Microsoft thinking of its own Windows RT tablet? No one knows for sure why, or even if that will be the focus of the company's quickly-called press conference later Monday, the New York Times notwithstanding.
Some analysts believe a Windows RT tablet backed by Microsoft's name could serve as a benchmark for other OEMs, or prod them into creating their own devices. It could be product "designed to get the industry excited" about the new operating system and the type of devices which can run Windows RT, Rob Enderle of the Enderle Group told Computerworld last week.
A corollary to that: It's possible that Microsoft is worried about the lack of interest by OEMs in Windows RT.
While several long-time computer-making partners of Microsoft have announced or hinted at plans to build mobile devices -- tablet as well as hybrid hardware that combines elements of both touch tablets and ultra-thin laptops -- using Windows 8, few have committed to working Windows RT into ARM-powered systems.
Or it may simply be that Microsoft has seen the Apple light, and decided that to be successful in the tablet space, it must mimic its rival's end-to-end control of the hardware and the software.
Isn't it risky for Microsoft to directly compete with its PC OEM partners? Definitely. Although Microsoft has a mixed track record with its branded hardware -- the Xbox has been spectacular, but it pulled the plug on its Zune music player -- it's never competed head-to-head with its OEMs in the PC or mobile markets.
That risks alienating the OEMs, who would be at a disadvantage because they must pay Microsoft licensing fees for Windows -- in the case of Windows RT, reports have pegged those fees as high as $85 per unit -- while Microsoft itself would simply be moving numbers around on its spreadsheets and financial statements.
Google faces the same conundrum with its acquisition of Motorola; Google-branded Android smartphones or tablets would conceivably tick off other handset makers who rely on Android.
That's why the expected debut of a Microsoft-branded tablet is such big news: In it's 37-year history, Microsoft has never gambled like this.
Where can I get more news of Windows RT and today's likely tablet announcement? Here.
The Microsoft press conference will start at 4 p.m. PT (7 p.m. ET) today. Computerworld will be covering the event with a live-blog and with on-site and analytical stories at its conclusion.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is [email protected].
Read more about mobile oses in Computerworld's Mobile OSes Topic Center.