'Santorini' is Microsoft's new 'Windows Lite' OS codename

Windows 10 Wallpaper
Windows 10 Wallpaper (Image credit: Microsoft)

Late last year, reports of a new Microsoft OS called "Windows Lite" began to emerge, and they detailed an OS built on Windows Core OS, that aims to take on Chrome OS with new user experiences and a focus on the web. Over the last few weeks, however, I've spotted references to another codename that appears to be in use when talking about Windows Lite in a lot of areas internally.

According to my sources, who wanted to remain anonymous, the codename "Santorini" is being used to talk about Windows Lite. Up until recently, "lite" was what people internally were calling it. It's unclear why exactly Microsoft is also using this codename, but if I had to guess, it's because the "lite" codename is a terrible representation of what Windows Lite is all about. Windows Lite isn't a lesser version of Windows; it's an entirely new OS experience designed for lightweight computing. It probably won't even be called Windows because of this. And for reference, Santorini is one of the Greek Cyclades islands in the Aegean Sea.

Santorini is one of many different flavors of Windows Core OS, joining Aruba, Oasis and several others that are currently in the works internally. We've already had a glimpse at Aruba with the unveiling of the Surface Hub 2X, of which I had the chance to go hands-on with back at Ignite 2018.

In just a few days, Microsoft is also expected to unveil HoloLens 2, which should mean a look at the work Microsoft has been doing on Oasis as well.

When will we see Santorini?

Chrome OS

Rumors suggest Microsoft is planning to talk about Windows Lite at its Build developer conference in May (opens in new tab). If so, that will be the first time the public gets a preview of Santorini, the version of Windows Core OS that we'll likely see shipping on foldable PCs and more traditional laptops and 2-in-1s, codenamed "Centaurus" and "Pegasus", respectively. The Santorini experience is slightly different depending on whether it's running on a Centaurus or Pegasus device, so different hardware use cases don't hamper the OS experience.

I'm told Microsoft has started talking a little more about its Windows Core OS plans internally. The company confirmed in a recent all-hands meeting that HoloLens 2 will ship with Windows Core OS, and even demonstrated a Windows Core OS device that was able to restart and install updates in under one minute, which is impressive.

I fully expect to hear more about Windows Core OS's different flavors throughout this year, hopefully starting at Build in May. While I don't expect we'll see any Windows Core OS devices start shipping until, at the earliest, later this year (my bet is we won't see anything ship until 2020), that doesn't mean Microsoft can't start talking about them with developers and partners.

What are your thoughts? Let us know in the comments.

Updated: Added clarification about the Santorini codename's use internally.

Zac Bowden
Senior Editor

Zac Bowden is a Senior Editor at Windows Central. Bringing you exclusive coverage into the world of Windows on PCs, tablets, phones, and more. Also an avid collector of rare Microsoft prototype devices! Keep in touch on Twitter: @zacbowden.

  • Interesting, does this mean we will see Windows + place names or something else entirely? A resurgence of Midori perhaps?
  • Windows Mojave, perhaps?
  • I understand the need to "get it right" but with Samsung already unveiling the Samsung Fold and shipping it in April, that will give them a huge lead in the foldable space, which Microsoft has been working on for some time. In addition, by the time Core OS ships to the masses, it's going to be that much harder to prove its worth alongside the by-then-established Android foldable space. I'm worried that Microsoft will again miss out on an opportunity to reclaim marketshare in the mobile computing space. It's Windows Phone 7 all over again.
  • Well, Microsoft shot both of their feet off when they axed the mobile division as that eliminated any sort of momentum they had and any future opportunities. Not to mention the missteps with UWP... It's highly concerning that Microsoft keeps insisting on using developers to QA test code.
  • How did they shoot themselves in the feet? Getting rid of loss making businesses is the way forward for most companies. Android is one giant beta test for end users and developers, hasn't stopped Google grabbing most of the mobile space.
  • "with Samsung already unveiling the Samsung Fold and shipping it in April, that will give them a huge lead in the foldable space"
    How many $2K foldable phones you think they're going to sell in 2019 when Apple has trouble with iPhone Xs? I question how some of you think technology works. It's not who does it first, it's who does it right (see Apple with iPhone in 2007 vs BlackBerry, Windows Mobile, Treo, and Nokia, or the finicky wearable market, which still hasn't settled). Moreover, there will be a response from Apple and more worrying all the Chinese Android manufacturers who will 100% undercut Samsung for price and likely even features - just as they're doing now. What's not clear is if foldable phones will solve the second-year-in-a-row dip in phone sales across the board. It's great to see foldables coming to market, but this will be a few years before the dust settles on this new category. Samsung has demonstrated over and over again they're really bad at first-gen products. Took years for Galaxy brand to really take off and differentiate it from the heard (I mark GS6 as the turning point for them).
  • Thanks for this response Dan. Apple (as much as I loathe to admit it) is a classic example of a company that knows that getting it RIGHT is key, not so much getting there first - of course within certain reasonable limits. See the iPod all the way to the iPhone and then iPad, even their notebooks, apple pencil etc. They may be late to the party, but when they show up, they deliver on a level that often makes the competition look incompetent, even if they copied the original concept from them :-(. Although these days, the gap is shrinking, but still the lesson holds.
  • You have a couple things wrong here Dan. 1. Getting this right is all hardware. Software for 5-8" touchscreens has been mature for quite a few years now. The transition makes it a bit interesting, but that is simple. It certainly isn't going to make any difference. This question is all hardware. Microsoft and Apple can't compete with Samsung's Display technology. Microsoft isn't going to out hardware Samsung and they have basically no software for such a device. Samsung's hardware chops will win this one easily. Eventually Microsoft will be able to source a decent flexible display, but they will not have Samsung level quality displays for at least a few years. Combined with the lack of software, Microsoft will have a hard time bringing a device to market, let alone one that can compete with Samsung/Android. I doubt Microsoft will release a device that competes with the Galaxy Fold. They will stick with larger form factors that can take advantage of their current mature ecosystem. 2. The Galaxy S devices blew up with the S2 and the S3 cemented them as the premier Android manufacturer and brand. I agree the S6 brought hardware quality not seen in previous Galaxy devices, but they were well established at that point. The Galaxy S2 was the turning point. Samsung Galaxy has been the number 2 smartphone brand since then.
  • Of course, this is why MS does not want to go in on the same 'phone' turf, they know the software ecosystem (user apps) is essentially non-existent and they can't win that game. At this point, they need a brand new landscape. Don't know what that will be, but it most certainly should not be 'smartphones' in the ordinary sense.
  • The only way it isn't a "smartphone" is if it doesn't fit in your pocket. This is exactly what I was saying. Microsoft will release a much larger device that aims to replace your laptop, not your smartphone.
  • I have to agree with Bleached on this one. MS has all but killed its mobile ecosystem and burned its ashes. MS cannot compete in foldables. Period. Having twice the screen size of a phone only makes it twice as painful that I have no CitiBank app. It’s only chance is to try in vain to compete with laptop sized Chromebooks. Even then in the end I think Nadella the great retreatist will abandon Core OS and release its own MS branded chromium OS variant. Every day there fails to exist a small form factor device to run MS store apps on is another day developers spurn anything having to do with MS and light computing.
  • Why would you think all potential Microsoft users want a Citibank app? I certainly don't. Why instead aren't you asking Citibank why they aren't getting with the times and making a PWA, or better still a UWP for the millions of Windows devices out there?
  • Funny that you mention a banking app. I switched to Android from Windows a little over a year ago, and I installed my two banking apps and just yesterday I realized that I never use them. In fact I barely use any of the apps on my phone, except for the basic stuff like email, texting, dialer, calendar, to do list, browser and some news apps. When I was a windows phone user people used to say "Oh, you don't know what you're missing because you're using a Windows phone", but now that I'm on the other side, I still don't know what I was missing. This whole app thing is way overblown.
  • "Getting this right is all hardware."
    100% wrong. It's the software experience. It needs to be something different and let users do something new that they couldn't do before to justify getting/wanting this as a phone. Simply having Android on two screens (or one large one) is not unique. What does this phone do so much better than it justifies the $2k asking price? Just saying "it's bigger" doesn't mean much. Galaxy Fold is 7.3-inches. My Mate 20X is already 7.2 inches and it supports a pen (no mention of S Pen with Galaxy Fold). ZDNet summed it up: "Galaxy Fold: I want the specs, but no clue what to do with a $1,980 foldable phone"
  • The big issue I have with the Galaxy Fold is that, for me, it's too small as a phone, and too small as a tablet. It's a great stepping stone for what can be done, but in its current iteration it just seems completely useless to me.
  • Once it is unfolded, how is this device any different than any other small tablet? What do you expect an 8" tablet to do that other 8" tablets haven't done? You are trying to discount the innovation here. What this device has to do is operate as a 4" phone when folded and unfold to an 8" tablet. The screen has to look good and be durable while doing it. For Samsung, the software and ecosystem is basically done. It uses their 4" Android interface when closed and their 8" Android interface when closed. The apps already exist and most have specific designs for each of those screen sizes. If the screen holds up, which is all this device is about, then it will be a success. The next gen will certainly be more accessible and refined. It could blow up.
  • It's both hardware and software that matters. Right now the Android tablet experience is...less than stellar. The folded phone experience on the device also looks terrible with the gigantic bezels around the screen. It still looks like a cool device and I'm glad Samsung is pushing it. But it's way too expensive and doesn't solve anything new while compromising on what we already have.
  • That would be a very limited iteration of a foldable UI. Which should include; tent mode for viewing, the additional screen as a keyboard, the additional screen as gamepad or writing pad, apps that utilize the bend, and all conceivable variations. If it has simply "closed" and "open", it's not maximizing the possibilities.
  • "What does this phone do so much better than it justifies the $2k asking price?" Nothing. Matter of fact, if you truly read up on it, Samsung's first attempt manifests in a lousy phone experience and tablet experience, plus it's thick (14mm) and clunky looking. On a side note, I don't see all the excitement regarding folding phones. I find technologies / products like HoloLens ( HoloLens 2) to be far more cutting edge.
  • Cutting edge maybe, but HoloLens is also quite useless for the average person, isn't it?
  • Not really. With enough miniaturization, in a true glasses form factor, it could eventually replace the smartphone, even the PC and TV as well. Keeping in mind how much shrinking all technologies so far have experienced. If light enough, it has the potential to be a replacement for a host of current tech for the everyday person.
  • NO NO NO! Getting it right is not all about hardware & never has been. It's about making technology accessible to the masses via software which is why Windows & iOS have been so successful as practically anyone of any age can use them, technophobes included.
  • True, usability is everything. A literal monkey can use the Instagram app. A grandma can use windows.
  • If you are so pro Samsung, and Android, and are so 100% always positive Microsoft is destined to eventually fail at everything they do, not to mention the fact that you think everything MS does can be replaced by Google, Android, and Samsung, solutions,, why would you waste your time on Windows Central? Why are you here? Answer that.
  • He's a sad angry man with no life. Sorry, but there is no other explanation.
  • If software is mature on 8-inch devices, why has androids tablet share been dropping for years? IMO, they never got a foothold in a bigger screen space. Apple certainly did. If they did a foldable, I'd be concerned for any future competition. Samsung actually co-developed the graphene screen tech they are using here, and with their curved screen, with Microsoft under Balmer (they co-announced in 2007 I believe). Balmer was more interested in 'wall screens' for things like xbox, whilst samsung for the folding phone. Sure, they have the manufacturing and branding to make it work for them, but I do genuinely question what the practical selling point of an android foldable is. Like with smartphone uptake, if you didn't have one, well you just couldn't do the stuff. With a foldable android, it's the exact same stuff on a bigger screen (but for 2k). Which is part of why tablets slumped. A big smartphone is close enough. With the ipad, the software is evolved enough that the extra size is a boon, hence why they held on strong. Android just never had that 'feature rich' bigger screen UI development. Even samsungs efforts with DEX have been WAAAAAYY less successful than either UWP or apples iPad apps (in terms of volume of scalable feature rich apps). Perhaps I'd consider DEX to be moderately more succesful than continuum, but lets face it, that's like saying something is slightly more successful than chernobyl. Google in general has the exact same issue with ChromeOS. They aren't bringing linux emulation to Chrome for developers, they are bringing it because their sad little App store, isn't made more of a 'big screen experience' by the addition of android small screen apps. Also why they are pushing PWA, because as polished as the small screen experience is, they are really struggling to break through anywhere else (outside of US education, for with their sad little app store works ok). I feel like that's not really worthwhile at all for consumers until the price drops massively, this who samsung flip. It's a loss leader for future dev. Basically all you get is more reading space, and better movie viewing (and that experience isn't THAT great on a tablet anyway). And _maybe_ like with microsofts gambit on andromeda, it encourages more dev in the underdeveloped big/small screen space. Commuters who are really rich aren't all that common. Productivity wise android doesn't buy much. Apple is much bigger in commercial spaces. MUCH bigger. I just don't see it having any kind of rapid uptake. Windows on the other hand, actually has a decent niche. It's software developers make the kind of software that rich people will pay for, if only to run illustrator or similar on their uber ride. Who do you see is the market for a 2k android device with an under 8 inch folding screen? Describe them. How many are there?
  • > How many $2K foldable phones you think they're going to sell in 2019 About as many as $1K Windows-on-Arm devices were sold in 2018. There will always be individuals and businesses who can justify spending money on things...
  • I bet they sell every single Galaxy Fold they make. They will easily hit their numbers and the subsequent cheaper variations will sell in huge numbers if the hardware proves to be solid. At $1000-1200, with proven hardware, the sales could be huge.
  • That is a bad bet.
  • I doubt they will make very many. Have they announced US availability? Will carriers have it?
  • That's not saying much when we have no idea how many of them they will make. You're just talking out of your behind like usual.
  • "About as many as $1K Windows-on-Arm devices were sold in 2018. There will always be individuals and businesses who can justify spending money on things..."
    That's not actually a measure of success.
  • The thing is, you're looking at this from an American perspective, a large number of other countries don't make their sales off selling phones outright, it's on plans. It's pretty easy to sell a $3000 phone (the cost it'll be in Australia), when it's given to you on a $99 phone plan.
  • Said the guy who measure success with Surface, saying ~"It creates new categories, but it's a careful game, because Microsoft doesn't want to shadow its OEM partners". How many categories created Surface Studio, Surface Go, Surface Headphones, Surface Laptop? Can you name me at least 5 Surface Studio lookalikes since its introduction noteworthy? And is there actually a real number indicating users even using their laptop's touchscreens, because my company bought all 1000 touchscreen Lenovos and when I ask collegues noone is ever using the screen. They buy this sh*t, because it's the OEMs are producing them and raising the price.
    My parents bought Lenovos too, used the flashy touchscreen feature for exactly 1 week, then never ever reversed the screen on the Yoga, because it's just pure sh*t. (Won't even talk about how Windows 10 is not for touch).
    It's EXACTLY like 3D cinema. Noone on earth prefers this bs, instead of normal cinema experience, but Holywood that has run out of original ideas long time ago, keeps pushing 3D movies and raises the ticket price and we pay because we want to see a g*ddamn movie. You should work on your measurement game, before bashing others. Surface is not a failure by any means. It's just barely a success. Almost irrelevant numbers in the wild, compared to Macs and everybody knows and clearly sees this. You can also measure the influence comparing it to the Mac. How many people in the entire World have even heard of Surface and how many Mac?
  • I'm with you on the 3D movie comment. So annoying. The Surface on the other hand, I see it all over the place. It really is becoming the new Mac. The "cool" tech.
  • Brand recognition is also a terrible measure of success. Microsoft recently ranked the highest valuation in the world, off the back of azure, that most people have never heard of, and xbox studios (with a smaller amount from surface and personal computing), which isn't really branded on the titles they sell. Money is the measure of success. Whether you gain, or lose it, and whether you can turn that loss into a gain. Apple nearly went bust. Then they were big. You're only as big as your last win, really. So it's always changing. That's why companies make long term and short term investments.
  • Doubtful. A windows on arm device has instant on, and longer battery life as a productivity point of difference. And the sales there were hampered by CPU speed, which will increase every year. Businesses don't waste money intentionally on useless crap.
  • Heard? Really Rubino 😂😂😂 I expected more from you seeing as you are a professional writer 🤣🤣 Jokes aside I agree with you. I think Samsung is trying to go on that being like Jewelry look that Apple did with the iPhone.
  • "What's not clear is if foldable phones will solve the second-year-in-a-row dip in phone sales " What's equally unclear is if foldable Windows PCs will solve the eighth-year-in-a-row decline in Windows PC sales.
  • We've had foldable PCs since the 80s. They're called laptops
  • It isn't entirely who gets it right if you enter a saturated market which Microsoft found with Windows Phone. Despite starting the market. Everyone marks the GS6 as the turning point, it's when Samsung started listening.
  • It's interesting that of the potential obstacles to the Samsung Fold being successful that Dan mentions: 1. It's expensive
    2. Apple might come out with a foldable phone
    3. Chinese Android manufacturers might undercut them on price
    4. Samsung is bad (according to him) at first gen products The one obstacle he doesn't mention is: Microsoft will release their fantastical mythical "beyond the curve" ultimate mobile device known as Andromeda!!! and blow everyone else's always connected foldable Pocket PC with telephony out of the water! You know who has demonstrated over and over again the they are absolutely terrible being successful at mobile hardware / software - MICROSOFT!
  • One thing I would say I've learnt about tech over the last two decades is that sometimes, being first out of the gate is not always what is most important. Getting it really RIGHT, as far as the experience goes may be what matters. Of course, being first mover has huge advantages in terms of software ecosystem, but for MS right now, they have nothing to lose since they are already far behind on the mobile software front (we can say that is a lost cause on the phone side of things). In this case, they need a unique end-to-end experience and delivered as a 'new' platform, similar to the approach with HoloLens, not a me-too phone wannabe. They can't win that fight imho, it's too late for that. I would rather they take their time and get their angle and argument RIGHT out of the gate. No use rushing at this point. Getting it right is critical.
  • I agree that there needs to be a sense of urgency. I don’t get that vibe from MS. I do get it from Google’s OEMs. Hence the sneak peeks. I think the “get it right” folks are wrong. It’s actually the “first to get it right” that takes the prize. And I’m not convinced MS is hungry enough to put in the hustle necessary to be the first to get it right. They could change my mind by talking about Core OS at Build. But I’m not holding my breath. My bets it will be the same boring visionary dribble they’ve been shoving down our throats for the last 5 years. All talk no action.
  • I would normally agree with you, but first to get the Smartphone right was Apple, but who has the biggest market share now? It's not even all about marketting, lets face it Apple are top at that. It's all about delivering what the customers want, and probably more importantly figuring out what they want. To be honest I fully expect lots of issues with folding screens, I wouldn't want to be any of the companies introducing them at the moment, when in a years time we'll be talking about stretched fold areas, cracking and faded pixels, probably :-)
  • I think Apple can be pretty proud of its market share. Plus its ecosystem remains the most profitable for developers. MS has extra onus on it because of letting UWP rot for 4+ years. Their whole software “plan” seems to revolve around praying PWA takes to wing, but we see that evolving at a glacial pace. We don’t even see MS themselves releasing PWA apps. Microsoft faces a chicken/egg issue. It needs a small form factor device before UWP stands any chance of surviving its life support status or for PWA to see any real uptake. It really doesn’t matter how much time they put into the perfect hardware if the only thing folks can run on it are legacy web apps through Edge.
  • "...that will give them a huge lead in the foldable space."
    At the market they are selling it, no.
  • ....... drum roll please!......... the codename is........... NoOneCares! :D
  • An All-Hands meeting about the OS is huge though.
  • Santorini a beautiful greek island!!!
  • How long do you think there's going to be between the HoloLens 2 announcement and it's availability? Or were you not counting it as a Windows Core OS device because of the form factor differences?
  • Maybe they can have live wallpaper as Apple does. but instead of the Mojave desert, they could use the Santorini's sunset and sunrise.
  • Now that would really be cool, especially on the lock screen and if Microsoft ever learns to put user name in the corner -- I mean having your name plastered over the Santorini sunset would be just a waste of a sunset... having your name on the picture of the bullfrog... c'mon Microsoft... :)
  • If at first you don't succeed, try, try, try, try, and try again. At least where software is concerned, on the hardware front just give up instead. As an aside, I really hope this isn't what comes on a foldable device, if I ever decided to get a foldable "phone" it would be to replace my tablet and phone, and for that I need legacy support otherwise I can't run the software I need so it's just a ridiculously expensive (I think we can all agree the Microsoft foldable is going to be priced exorbitantly high) Facebook machine.
  • As long as there is a tablet version it's all good.
  • Lol wow I think people underestimate him the stuff just wow by the way how in the hell did you get full portable telephones foam talking about Windows light just saying guys.lol right now tablets and smartphones all in steep decline. The question is now can Microsoft and the surface of the ocean save the tablet market and the smartphone market no one knows .
  • I appreciate all the comments about whether it is best to be first to market or first to get it right. However, in my opinion, Ms is not even in the market. What is its proposition? Azure and Hololens? They are just out on the margins of mobile and cannot get any closer to the centre without a significant product. Google and Apple must be laughing their heads off, not to mention the Samsungs, Oppos, HMDs, Huaweis and all the rest who are beginning to eat Nadella's breakfast.
  • Microsoft is doing better than all of those companies if we're going by valuation.
  • Not bad. Greek islands ring a positive note for most...
  • WHAT?! Santorini??!! The mere scrap of an island left after Thera blew it's top, lead to the collapse of the Minoan civilization and prompted the wingnut theory of Atlantis because of the destruction it caused? Are all techies this culturally and scientifically illiterate??
  • I still wonder what this is going to run? Web Apps are absolutely the future but Google found out that they're not enough and brought Android apps to ChromeOS. Microsoft can't do this as UWP apps aren't Android apps in their choice or quality. If Windows Lite only runs Web Apps and UWP Apps, even if it's a nicely designed Operating System and on decent hardware I'd pick a Chromebook any day. Google is an online first company. Microsoft has consistently shown it's not. Nearly all of Google's Online services are better than Microsoft's.
  • I have read web sites reports that Microsoft was shrinking Windows 10 to fit on Tablets that
    had 16 to 32 gigs of main memory. Obviously Microsoft has done more extensive work to
    do this in away Windows 10 can work very well with less Dlls, Drivers & ECT than FULL
    Windows has. Hmm it looks like Microsoft stripped down Windows 10 so well they created
    a NEW OS. This does not shock me after all Windows 95/98 & Windows NT-4 worked well
    and used far less hard drive space
    then Windows 10 does today
  • Great job Microsoft Santorini is the wave of the future for Windows light computing devices
  • Like Windows RT and Windows S, right?
  • new code name.... I offer a golf clap... meanwhile Huawei Mate X and Galaxy Fold have launched andromeda, centaurus…. meh