Understanding Windows Core OS and Microsoft Polaris

A new reality beckons. Microsoft is currently working on a secretive project, dubbed Windows Core OS, with the goal of unifying the operating system across all devices.

We have also been hearing talks of Polaris, as well as something called CShell.

What exactly are all these? Versions of Windows? Codenames for devices? Elements of a new strategy that the company is pursuing? We’ll take a look at these in detail and try to decipher the picture of what promises to be the very future of the Windows operating platform.

One Windows to rule them all

Microsoft has been working toward unifying its operating systems for the better part of the decade. Windows 8 was our first hint, but Windows 10 really things kicked into high gear when it brought together the core platform across devices. It was a clear signal that the company was moving away from its style of monolithic OS releases towards something that was more singular and unified.

one windows platform

The next couple of years saw the main Windows 10 architecture brought to devices like new types of PCs, Windows 10 Mobile smartphones, Xbox, HoloLens and Surface Hub. But this approach only unified the kernel — meaning each platform needed its own engineering team to maintain.

Not exactly the definition of unification, right?

More work was needed.

Now before we dive into the technical details, it is worth a mention that these concepts can get a bit murky to follow along. To help you better understand them, we have included is a short rundown of the key elements below, with the details following right after.

  • Windows OneCore was the successful unification of the kernel and the core OS components that Microsoft completed in 2015.
  • Universal Windows Platform (UWP) was the fusion of its app platform, which was designed traditional x86 and x64 systems, as well as ARM and Xbox.
  • Windows Core OS is the big bet from Redmond to make Windows 10 truly modular. This is still a work in progress. When ready, the operating system will look the same, but Microsoft will easily be able to add or remove components like support for Win32 desktop programs or telephony for cellular calls.
  • Windows CShell is the last piece of the puzzle, the user interface. Redmond is going for a UI that adapts to the screen, enabling the possibility of devices adjusting their interfaces for different tasks and experiences. As you may have guessed, this takes forward the idea behind Continuum.

With the board now set, and pieces in place, let’s find out how exactly will Microsoft create a modern version of Windows for the future.

Microsoft’s Unification Game Plan

One thing you may have noticed is that not all of this new territory for Microsoft. The company has already tried its hand at releasing a trimmed down Windows in the past — Windows 10 S launched with appropriate fanfare not too long ago.

But since that version used the full code and merely limited users to UWP apps, they were still able to upgrade to the full edition of the operating system.

This time, though, the software giant is aimed for full modularity. The plan is to create a unified operating system for all Windows device, whether that be Windows 10 for the PC, variants for server, mobile and IoT, or for devices like Xbox, HoloLens and Surface Hub.

As mentioned above, Redmond today already has a project called OneCore, which accomplishes a fraction of this goal. But this scattered approach means that the company is not there yet. Instead of different operating systems based on the same core, Microsoft now wants to create a single modular operating system built on top of that core platform.

Windows Core OS is the answer.

Windows Core OS : One OS for all Devices

Microsoft bills Windows Core OS as a monumental step forward in making Windows a truly universal OS, one that works across platforms, on any device type or architecture. This, it will accomplish via the use of modular extensions that enables devices features and experiences as and where necessary.

In some ways, this is the Continuum concept taken to the extreme.

As a matter of fact, a job posting has the company referring to Windows Core OS as a new operating system in development behind Redmond walls. The OneCore team is actually involved with this, and helping create a single base operating system for all devices.

Mary Jo Foley of ZDNet dug a little deep into this, and found out that Windows Core OS was previously known as AndromedaOS inside Microsoft. The reason for that was because it would have launched on a new, dual screen hardware device called Andromeda that was rumored for arrival this year. It may still launch in 2019, though the latest on the matter is that Microsoft has gone back to the drawing board.

windows core_os structure

Coming back to Windows Core OS, this is the main ingredient of the Windows Polaris soup.

The baseline platform that Polaris and other iterations will be built upon.

What this means that hardware makers will be able to bring to market devices in any form factor. These devices would be powered by their very own Windows operating system, with only the features they need. This last part is the important bit here — as not only would this make the whole experience easier to understand for users, but also speed up performance and enhance battery life of these machines.

All this is quite similar to the operating systems that have come to dominate the mobile space, Windows is simply evolving in this direction. Once the various components of Windows Core OS are in place, Microsoft is expected to release a number of variants of that baseline.

One of which is Polaris.

Polaris: Desktop Interface

One of the more interesting aspects of the Windows Core OS concept is what Microsoft refers to as composers. These are the user interface experiences that will define the variants, the shell or the UI of these operating systems, so to speak.

The kernel, app layer and OS level components will remain the same, the only difference between the variants will be the composers. We may get a composer for tablet, another one for mobile, and one for the desktop, obviously. These are simply put, the flexible shells that Windows Core OS will express.

A modular operating system, with the shell now being the defining variable.

A device could, in theory, have multiple composers. For example, it can act as a mobile handset but also shift to desktop mode when needed. This is where the different composers come into play, with talk of a mobile shell (Andromeda), a desktop shell (Polaris), a mixed reality shell (Oasis), another one for the Surface Hub (Aruba), and so on.

surface devices

Now, you may be thinking all this is basically a drive to mirror the streamlined mobile operating system like Android and iOS. And while that is true, Microsoft is in no way forgetting the desktop and laptop market, which are the mainstay of the Windows platform.

Polaris, codename for this new project, is basically an attempt by the company to strip back all the legacy elements of Windows, making the OS as lean as possible.

These legacy components are what make Windows so compatible with all the hardware and software out in the wild. But this bloat also hinders the operating system from operating as efficiently as it can, particularly on lower end devices. It also complicates things from a security perspective.

This doesn’t mean that Microsoft will remove all Win32 functionality from these variants — that is simply impossible from a development perspective.

However, it plans to remove as many legacy systems as it can to streamline the Windows operating platform for the next decade. And the myriad devices that will make their way to store shelves, the PCs, tablets, 2-in-1 hybrids, smartphones, game consoles, servers, IoT hardware and mixed reality headsets.


Composable Shell, also known as CShell, also known as C-Shell. This is another part of the Windows Core OS puzzle that Microsoft is developing, with the goal of positioning this as the default environment for all Windows devices.

As thing stand, devices that run variants of Windows all come their own interfaces — the desktop on computers, phone interface for Windows powered smartphones, and the dashboard on Xbox One. While they make all these different devices unique, they also bring in complexity when it comes to maintenance and addition of new features.

CShell aims to fix this.

In a nutshell (pun always intended), this is shared interface that will run on top of Windows Core OS. In other words, a modular shell for a modular operating system.

surface hub cshell

Microsoft is designing it to intelligently and automatically adapt to any device in real time, no matter the form factor. For example, a PC in the future could switch to a phone interface and vice versa, or a gaming device could transition from an Xbox One dashboard to a Windows desktop in an instant.

And although we have been seeing early demos of CShell up and running since 2017, it remains a work in progress as we head into 2019. This is what will hold everything together for the Windows Core OS concept, and Microsoft understandably wants to get it absolutely right the first time.

After all, CShell will be what users will interact with the most on this new breed of devices.

How will a Polaris PC be different?

We now get to the $64,000 question! What differences can you expect from a PC powered by Polaris, or even any other form factor device powered by this trimmed down, modular variant of the Windows operating system?

Unsurprisingly, the first time you see a Windows Core OS laptop running Polaris, the experience will look just like Windows 10.

Underneath, however, things will be different.

A lighter, more secure OS that leaves behind legacy components has to make certain tradeoffs. And Polaris being the desktop and laptop specific composer of Windows Core OS does come with a few limitations, the most notable being the inability to run Win32 programs — natively, at least.

The current Windows Shell is one of the major legacy elements that what Microsoft is replacing with CShell. And that means classic programs like Notepad or Paint will be replaced with UWP experiences. Some of these are already available on the Microsoft Store, others are coming. Redmond is also hard at work converting the remaining legacy settings, applets and functions into UWP.

Other functions like fax support and the Control Panel could be lost, however.

While it seems unlikely that Microsoft would remove the functionality entirely, there are suggestions that the company is looking at virtualization and cloud streaming to allow legacy applications to run on Polaris. For virtualization, we have signs that the software titan will use RAIL to enable remote virtualization. But while this makes a world of sense for enterprise users, the company is also looking at local virtualization for consumers and home users.

At the end of the day, a Polaris PC designed on top of the Windows Core OS platform will offer the most secure and snappy experience possible on the given hardware.

Windows Core OS hardware landscape

If all this sounds appealing and you are ready to hop onto the Polaris train, then you will be pleased to know that Microsoft plans to launch this as a separate project once everything is ready — Polaris and the traditional Windows 10 Pro will exist in unison.

It is unlikely there will even be an upgrade path between the two versions.

Polaris is aimed at the casual user who is in no need for programs like Premiere Pro or Maya. It is aimed at users that are comfortable with doing most of their work in a web browser window, use cloud-based productivity apps, and consumer content from Netflix or Spotify.

Provided things go according to plan, Polaris will become the mainstream version of Windows 10.

It will not be forced on anyone, instead new PCs will be marketed with this leaner operating system. Even then, consumers will not likely be the first target — a smart strategy, and a sign that Redmond has learned well from the past.

windows snapdragon

Word is that Microsoft wants to position this new flavor in both education and enterprise — primary and secondary schools, as well as first-line and information workers. Windows Core OS will also come to new Always Connected PCs and Windows 10 on ARM devices that offer features like instant-on, 4G LTE connectivity and battery life that can last weeks.

The Windows 10 that is available today will stick around for gamer and power users that demand utmost in performance. Polaris, meanwhile, is only expected to be available on new devices that ship with it, likely as a replacement and purer version of the locked down Windows 10 S.

The Future of Windows

The Windows Core OS is a big deal. It is the future of the OS that enables Microsoft to build a more flexible and agile operating platform for all the computing needs of tomorrow on current and future form factors — whether they be on a handheld or an 85-inch touchscreen in the office.

It also finally allows Redmond the luxury of streamlining the development of Windows, where it can pour more time and resources into improving existing features and building new ones, instead of spending time fixing them.

This has been a change a decade in the making

Yes, there have been a few missteps along the way like the Windows RT fiasco, the eventual demise of Windows 10 Mobile, even Windows 10 S when you think about it. But it finally looks like Microsoft is on the right path.

One that will chart the future of its flagship operating system for the decades beyond.

2 thoughts on “Understanding Windows Core OS and Microsoft Polaris”

  1. Basically,Microsoft will want to use a skeletal system sufficient to log onto the internet, etc.
    The rest of the operating system will be cloud based and depend on the system in use.
    What better way to make one drive mandatory. Of course there will be a monthly service fee.


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