No new versions of the low-cost Raspberry Pi computer have been officially supported by Windows 10 IoT Core since 2016.
The low-cost Raspberry Pi computer has been closely tied to Windows 10 IoT Core since the OS was revealed alongside the Pi 2 in 2015.
But in the intervening years the situation has changed, with the last Raspberry Pi that Windows 10 IoT Core officially supported being the Raspberry Pi 3, released back in early 2016.
Since then two newer versions of the Pi have been released, the Pi 3 B+ in 2018, and the Pi 4 Model B in June this year.
The uncertain future of Windows 10 on the Pi came to the fore again recently, when a Microsoft Contingent Staff member said she did not expect Windows 10 IoT Core to be compatible with the recently released Raspberry Pi 4.
"Given the need for a new Raspbian OS, we do not expect the existing FFUs [Full Flash Updates] for Windows 10 IoT Core to be compatible with this platform," she wrote.
When approached for clarification, a Microsoft spokesperson said the only official comment was that "we are excited to see the new RPi4 platform and are evaluating the numerous changes in the hardware".
It's important to note that Windows 10 IoT Core is not the same version of Windows 10 that runs on a desktop PC, but is a far simpler, stripped-back release.
This OS won't boot you into the traditional Windows desktop, but instead is designed to only run a single front end Universal Windows Platform (UWP) app at a time.
The real purpose of Windows 10 IoT Core on the Pi is to run small applications, which are deployed to the board from a PC. These apps could do anything from taking readings from a temperature sensor, to acting as a simple web server.
The lack of support on the Pi 4 is perhaps no surprise given there's no official support for the previous generation Pi 3 B+. The situation even prompted one Microsoft employee to put together an unofficial guide for getting Windows 10 IoT Core to work on the Pi 3 B+ using an unsupported technical preview
In general, Windows 10 IoT Core is lagging behind its desktop counterpart, with no final version of the May 2019 Update, version 1903, released for Windows 10 IoT Core as yet.
However, the fact that the Pi 3 B+ is supported, albeit with a variety of issues, in the latest technical preview builds of Windows 10 IoT Core suggests Microsoft hasn't given up on Pi support.
It could even be that Microsoft is planning larger changes to the OS to take advantage of the Pi 4's significant bump in power, with the low-cost board supporting up to 4GB DDR4 RAM, a new CPU and GPU, and dual 4K displays.
When it comes to the full desktop version of Windows 10, co-creator of the Raspberry Pi Eben Upton said ahead of the Pi 4's launch that he believes the Pi 4 has the power to run Windows 10 on Arm but that support was a "question for Microsoft".
So far there's been no indication from Microsoft it's thinking about adding such support and it's uncertain how well Windows 10 on Arm would perform on the Pi 4, given that early Windows 10 on Arm machines with octa-core processors and 4GB memory were criticized for struggling with web browsing.
Upton has also made the point that the Pi, with it's optimized Raspbian desktop and Chrome browser, offers "a Windows-equivalent environment" anyway, so the need to run Windows isn't really a pressing one.
On a related note, Microsoft has been similarly quiet when it comes to its use of Windows Server on Arm with its Azure cloud platform, with no significant updates on the project in the two years since it was announced.