More on Windows on ARM: Highlights From Sinofsky’s 8,600-Word Opus

We’ve already covered the highlights of Microsoft’s Windows-on-ARM news Thursday, namely that it will have a desktop mode, but only for Office, Internet Explorer and Windows itself.

However, there are some other interesting nuggets amid Steven Sinofsky’s epic blog post, which just posted.

There won’t be an “off” button for Windows-on-ARM (WOA), nor will there be various sleep modes.

One of the new aspects of WOA you will notice is that you don’t turn off a WOA PC. WOA PCs will not have the traditional hibernate and sleep options with which we are familiar. Instead, WOA PCs always operate in the newly designed Connected Standby power mode, similar to the way you use a mobile phone today. When the screen is on, you have access to the full power and capabilities of the WOA PC. When the screen goes dark (by pressing the power button or timer), the PC enters a new, very low-power mode that enables the battery to last for weeks.

Microsoft wants a say in how the Windows-on-ARM hardware works, much as it does with Windows Phone.

To those familiar with the Windows Phone 7 approach, the chassis specification, WOA shares some of those elements. The specifications being implemented for WOA allow for more diversity across many dimensions, combined with the same commitment to engineering and product excellence—all while running the same OS binaries across WOA PCs.

In order to test Windows-on-ARM, Microsoft first had to do so on phones, since no ARM tablets yet existed.

Early in the development of WOA, the only hardware we had were existing ARM devices such as phones (ARM tablets didn’t yet exist). We just thought you would enjoy a few fairly early photos I captured of debug WOA all loaded in RAM (unretouched). Note: This is not a product plan or even a hint at a product.

Sinofsky defends Microsoft’s decision not to let more existing Windows programs run in the Windows desktop.

If we enabled the broad porting of existing code we would fail to deliver on our commitment to longer battery life, predictable performance, and especially a reliable experience over time. The conventions used by today’s Windows apps do not necessarily provide this, whether it is background processes, polling loops, timers, system hooks, startup programs, registry changes, kernel mode code, admin rights, unsigned drivers, add-ins, or a host of other common techniques.

Microsoft is making some test Windows-on-ARM machines available to developers, but they don’t give much of an idea what real ARM-based Windows devices will look like.

To run this release, a low volume of test PCs specifically designed for WOA will be made available starting around the next Windows 8 milestone. These devices are for developers and hardware partners, and do not represent consumer form factors, by any stretch of the imagination. They have diagnostic tools and ports. They are designed to be opened and debugged. They do not have the final components or firmware (or power or thermal management) that a commercially available device will use. They are made of low-cost plastic. You might have seen devices similar to these on display at CES or demonstrated there, and all of our previous demonstrations have used some form of these test PCs. These PCs do represent WOA and the experience—but they no more represent the final experience than does the current state of x86/64 Windows 8. They will be running the same branch of Windows that will be made available to x86/64 testers at our forthcoming development milestone.