If you're asking, 'why does Windows RT do it like that?' The answer's battery life

If you're asking, 'why does Windows RT do it like that?' The answer's battery life

Summary: If there's something that puzzles or irritates you about Windows RT and you wonder why it's done that way, the answer is almost certainly battery life (or viruses).


Why can't you run desktop applications on Windows RT? If you look back at the picture of Windows running on an ARM smartphone, way back when Microsoft began experimenting with moving the Windows code to the ARM chip, you don't see a WinRT app. You see Solitaire — a familiar desktop app. If the desktop, a Windows application, can run and if Office, a (significantly rewritten) desktop app, can run, then why not other desktop apps?

Because they'd ruin your battery life — not to mention bringing all the malware that's written to attack Windows to a brand new platform.

As ex-Windows chief Steven Sinofsky put it when first announcing that Windows would run on ARM: "Our job is to allow the power, the flexibility and the choice of that architecture to shine through. If a processor package uses less power, the role of Windows is to let that reduction in power shine through."

Running desktop applications, nice as the idea is, wouldn't give you that. "Those apps don't take advantage of all the things that make ARM a unique offering. When you use an ARM chip you want great power management; in Windows 8 that's Connected Standby. An x86 app doesn't respect that and it's going to just drain the battery", said Sinofsky.

Anything you think is a compromise with Windows RT is almost certainly sacrificed to battery life.

Even more bluntly, at Build in 2011 he explained that "we decided early on that unless we could deliver the value proposition of that ARM hardware there was no point". Running x86 apps in emulation? "It would just undermine this whole thing." After all, an iPad doesn't run OS X apps — or as he put it, a little more subtly: "If you do run everything, all of a sudden [Windows on] ARM is saddled with all this stuff competitive platforms don't get saddled with."

But it's more than just having long battery life. It's about having what Pat Stemen (who's been working on power management in Windows since at least Windows 7) calls "consistent, consistently long battery life". The idea is that there shouldn't be anything that can fire up in the background and start using power, so if you know how large the battery is you know how long the battery will last and that doesn't change from day to day. No surprises.

That's why the thing Microsoft is most protective of on Windows RT is battery life, and anything you think is a compromise is almost certainly sacrificed to battery life.

Surface RT: see how it runs
That certainly delivers on the Surface tablet: you never really turn Surface off, especially if the Wi-Fi is on, and the battery just keeps going. On our last trip to the US, I was using my Surface on a Monday and I'd had it plugged in at some point that day. I used it a little on the Tuesday then flew back to the UK late afternoon. I pulled my Surface out of my bag on the Wednesday after we landed and used it a little. I used it more on the Thursday and the Friday and the Saturday afternoon. And sometime late Saturday night I finally had to plug it in. Now I wasn't using it all day long, but I was turning to it every hour or so to catch up online or read web pages and it was online pretty much all the time. My phone doesn't even give me that kind of battery life. Surface does it by turning the processor off any time it possibly can, leaving just the Wi-Fi running to accept incoming messages like email.

There are obvious design decisions in Windows RT that have nothing to do with battery life, like big tiles for touchscreens and contracts between apps that give you a richer version of the clipboard and the settings charm so you always know where the settings are.

Microsoft Surface RT: the battery just keeps going.

Not joining the domain or having GPOs (Group Policy Objects) is because a Windows RT tablet is mine, not the IT team's and I don't want someone else locking down bits of my experience because they don't think I can be trusted to play Minesweeper and get my job done as well. Plus, doing away with GPOs makes it much harder for those 'fixing' utilities that tweak system settings that do nothing but break your system. I spent five years writing a Windows XP problem page and once service-packing XP stopped it being the most malware-ridden platform I've ever seen, the vast majority of problems were caused by having run a tweaking utility in the first place (turning off services to save memory and then finding the features that rely on them don't work is making a rod for your own back).

But given how much longer a badly-written log-on script can make starting up Windows, not having GPOs might make battery life more consistent as well.

And when it comes to the familiar desktop and the places it's not quite the same on Windows RT, the things you sacrifice are mostly things that would turn the processor back on.

Windows RT can join a homegroup, but you can't share content with the homegroup — just access the files on other computers. That's one of the clearest pointers that Microsoft sees Windows RT as something you use with a PC, not something that replaces a PC. But it also makes sense. If you're sharing content from a device, you want that content to be available whenever that device is on, but Windows RT is on all the time even when the screen is off. If other PCs could wake it up to stream music or view photos stored on your tablet, it would hammer the battery life.

Microsoft sees Windows RT as something you use with
a PC, not something that replaces a PC.

The same is true of offline files. Although offline files is based on a service and services can be throttled (that's why they're the only part of the Windows desktop that runs in Connected Standby), it means Windows regularly polling the server to look for changes to sync down to the PC (over and above uploading the changes I make locally at intervals). It's a hugely useful feature, and not having it is one of the main reasons Windows RT won't be my daily travelling PC (the other is that I need active pen support so I can scribble down notes), but it's the wrong kind of connection pattern for a modern battery-efficient system.

Sync in Windows RT is perfectly possible; after all, it syncs my Windows settings and my Wi-Fi and website passwords. (I followed a link on Twitter today to a site I hadn't visited in a year, but my Surface had the password because a year ago or more I saved it on some other PC that I've since upgraded to Windows 8 and logged into with the same Microsoft account). Apps can sync information — I get push email and calendar updates and instant messages — but that's all push rather than the pull model of offline files. And OneNote syncs its notebooks quite happily to Windows RT, both the desktop and Windows Store versions.

Syncing from SkyDrive
Given that the settings sync in Windows RT is information actually stored on SkyDrive, as are my OneNote files, I'm still hoping it's going to be possible for a future version of the Windows Store SkyDrive app that comes with Windows RT to sync my other files from SkyDrive as well — especially now the SkyDrive API supports selective sync. Until we had selective sync, I didn't want the relatively tiny storage space of a tablet filling up with everything I have on SkyDrive. But now I could pick and choose what folders to sync, I think it should be an option.

If it isn't, I won't say Microsoft hasn't been thinking things through or doesn't get what users want. I'll say that whenever there's a trade-off to be made between features and battery life, Windows RT chooses battery life.

Topics: Microsoft, Tablets, Windows, Microsoft Surface

Mary Branscombe

About Mary Branscombe

Mary Branscombe is a freelance tech journalist. Mary has been a technology writer for nearly two decades, covering everything from early versions of Windows and Office to the first smartphones, the arrival of the web and most things inbetween.

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  • Desktop Mode

    I can understand why RT won't run legacy desktop apps. Yes, that would likely kill battery life. But why not allow developers to code desktop apps that are written specifically for RT, like those that come standard with the OS?

    That's my biggest gripe. I wish Microsoft would allow application makers to code for the RT desktop as long as the app includes an equally capable "Metro" tablet mode.
    • That would be pointless

      If it has "an equally capable "Metro" tablet mode" then a desktop mode is redundant.
      • In other words, ARM chips blow

        Saving power comes with the trade-off that your apps ain't run jack.
        • That is an eternal tradeoff, even in Windows on X86

          I have not seen any reviews of how a full Linux install may run on ARM, but LibreOffice is being ported. My gut feeling is that it would run better than a full Windows X86 port to ARM.

          I guess the conclusion, if true, is that Windows is more of a resource hog than Linux. I think the next couple of years will probably answer this question.
          • Hi Sales boy

            how cool to put your sales pitch for Linux on a Windows thread? If a Microsoft fanboi does the same, would you tolerate?
            Ram U
          • Re: If a Microsoft fanboi does the same, would you tolerate?

            I'm sure we'd be HAPPY to see a Microsoft fanboi suggest running LibreOffice. :)
        • Re: In other words, ARM chips blow

          Funny, they don't "blow" when running Android, only Windows.
    • I Agree

      The Windows desktop gives Surface RT the potential for content creation, software development, etc., but it's a waste to limit it to Office and the built-in desktop apps.

      MS should release a new desktop SDK that opens up the desktop in a battery-friendly way. This would probably require yet another new API, but it would be worth it. New, power-efficient desktop apps would benefit both hardware platforms, and RT would no longer seem like an incomplete platform.
      Guy Smiley
      • oh yea, tell me

        I would really love to develop on the RT desktop and compile, and run my apps. Imagine Visual Studio for ARM?
        • Running VS on ARM might be a stretch

          Most of the ARM's performance gain is coming from the GPU or specialized decoders. In terms of ALU (integer calculation), even top-of-the-line, latest ARM still no match for even Atom almost 2 years ago:


          And since code analysis compiling couldn't really benefit from GPU, I think you should know how slow to run VS on Atom alrady.

          The problem with ARM is there maybe too many cooks and too much compromises. Intel doesn't have to deal with all these ARM licensing and fabrication complexities. And it shows that Atom is fast closing in with Clover Trail in terms of power consumption.
    • Well there are certain functionalities that would

      get along with Desktop mode better than Modern UI mode, but wouldn't developing the same with equally capable "Metro" tablet mode be a redundant? probably I might be misunderstanding what do you mean by that?
      Ram U
    • I could be wrong, but

      Isn't that in the hands of the developers? Is Microsoft really preventing developers from developing tools allowing you to be productive from an administrative standpoint. Heck, they have the RDP application, which has a desktop version as well as Win 8 version.

      Microsoft needs to work with developers to ensure the API's offered are capable of developing powerful applications. I would think there is some serious potential in this device, but with Windows 8 Pro being backward compatible, and not much sales activity on RT devices, there might be a slow transition to developing Win 8 specific updates to existing client applications.
  • beautiful ! well put

    for once an article with brains by a tech-pundit/journo on the web
  • If ever there was a write-up about Windows RT

    that actually cut through all the subterfuge and double-talk normally associated with it, thus far - and in its very short life so far, than this blog is it.

    It's a very balanced, objective and sound, technical and aesthetic review of the technology. I do believe it's also the first time i've read a review that *actually* makes Windows RT an attractive, mobile computing proposition.

    This certainly puts new perspective on Windows RT that is as concise and unpretentious as should be the case always (optimistic in the case of ZDNet, in general).

    Excellent work, Ms. Branscombe.
  • Excellent Write up

    Finally a tech writer uses their expertise in the tech field to write an intelligent article about technology. I get tired of reading opinion pieces that offer very little outside what features the writers like. Substance, give me some substance! Of course, opinion pieces drive comments, which equates to more clicks, and they get promoted. However, for a place like ZDnet, articles like this should be the standard. Great job.
  • Simon, you just get it!

    I am just frustrated with these so called tech reviewers, all biased and ignorant idiots.

    Is it surprising that ARM based OS is not able to run x86 code?
    Is it difficult to understand Desktop OS on tablets is more powerful than Phone OS on tablet
    Is it difficult to understand that desktop grade features,tools and applications will take more space?
    Is it difficult to understand that touch and mouse/keyboard need to exist together for no compromise experience?

    Microsoft has pulled a leg up on its competition, while these tech writers are looking the other way
  • Well done

    Very mature review/point of view.
  • If you're asking, 'why does Windows RT do it like that?' The answer's batte

    Great article, reasons for it are well thought out. Microsoft knows a whole lot more about coding their OS on ARM then some of the bloggers on ZDNet.
    Loverock Davidson-
    • Learn the difference

      between then and than.
      • I'm pretty sure Loverock knows the difference, and typos do occur,

        and they're impossible to correct when there is no "edit" function.

        So, stop being so petty.