Windows 1.01 on the Raspberry Pi Pico
Charlie Birks has transported the Raspberry Pi Pico back to 1985 by booting up Windows 1.0 with the help of a custom 8088 CPU emulator.
When Raspberry Pi got into the microcontroller game with the Pico back in 2021, we all knew that this little board was going to be used for some very interesting things. Between the ultra-low price point, the powerful RP2040 microcontroller known for being ridiculously overclockable, and cool features like the Programmable I/O, hardware hackers couldn’t help but make magic happen with this little board. But one thing that is probably on no one’s radar is running Microsoft Windows on a Pico.
No one aside from Charlie Birks, that is, who managed to do exactly that. Now, while the RP2040 is great as far as microcontrollers go, it is hardly up to the task of running Microsoft Windows 11. It requires a bare minimum of 4 gigabytes of RAM, after all, while the Pico sports a paltry 264 kilobytes. And even if it was possible, installing a modern version of Windows would more than likely only draw scorn from the hardware hacking community, along with lots of reminders that Linux would have been a far better choice in every possible way.
But if you turn back the hands of time a few decades, say to the era of Windows 1.0, that all changes. At that time, a 264 kilobyte machine was something to be proud of, and there was no shame in being a Windows user yet. Wisely, Birks chose Windows 1.01 as the version to get running on a Pico.
Of course the Arm Cortex-M0+ processor cores inside the RP2040 are not compatible with the Intel 8088 processor that Windows ran on. So as a first step, Birks developed an 8088 emulator amusingly called the Probably Average Computer Emulator (PACE). PACE gets the job done, but it is not yet complete. There is still a little more work to do on the 8088 core itself, and little DMA support has been developed so far, so disk emulation is still on the hacky side.
The emulator does support graphics output, keyboard input, and crucially, it is complete enough to boot up Windows 1.01, however. Birks demonstrated Windows running on a Pico with a Pimoroni PicoVision to assist with the video output. The PSRAM on the PicoVision also enables the operating system to use up to 640 kilobytes of memory.
If you would like to learn more about PACE, or how to get Windows running on your Pico, there are unfortunately not a lot of details available at this time. However, source code is available on GitHub if you are willing to spend some time digging in.