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Saturn is a new operating system I started in Oct 2017. It is a 64-bit microkernel with multitasking and IPC based around asynchronous message passing. With the exception of LLVM's libc++ and FreeType, the entire system and services are being written from scratch by me in C++. Saturn is not just the kernel, it encompases all the services and drivers needed to provide a complete desktop system.

The repository is organized into simple sections. The entire kernel is under src/kernel, all services including Apollo are under src/services, and applications can be found in src/applications.


Latest Screenshot
Dsky application demonstrating Gemini interpreter


Apollo is Saturn's UI framework. Apollo has a tiled window manager that divides up the screen into tiles. One of the main goals of Apollo is to support rapid UI prototyping. To accomplish this, Apollo uses a declarative layout language called Mercury. By editing Mercury files you can easily create and modify an application's UI.


    (rows (fixed-height 50) (proportional-height 1))
    (columns (fixed-width 50) (proportional-width 1))

        (label (caption "This is a label")
            (alignment (vertical center))
            (padding (horizontal 10))
            (meta (grid (column 1))))

            (meta (grid (row 1) (column-span 2)))
            (item-source (bind entries))

                (label (caption (bind content))
                    (background (bind background))
                    (font-colour (bind fontColour)))))))

Apollo also makes heavy use of databinding. Certain UI elements like Labels expose properties that are 'bindable', such as caption and background. You can define properties in your application and then 'bind' them to elements, and when your values change it automatically updates the appropriate UI element.

Note that the example also shows item templates. You can create a collection of some user-defined struct, and by defining an item template you tell Apollo how to create UI elements from that struct.


Vostok is Saturn's Virtual Object System. It allows you to access objects exposed to the virtual file system just like files. Objects can have properties as well as callable functions, providing an RPC mechanism. By opening an object and writing arguments to one of its functions, you can invoke a function call in a separate process and read the results, just by using the filesystem. In the Dsky screenshot above, /system/hardware/cpu is actually a Vostok object, with a nested Id object that has a brand property.

A core feature of Vostok is introspection. By reading a Vostok object, you can discover all of the properties and functions they expose, as well as their types. By reading a function you get the function's signature, ie its input and output types.

/system/hardware/pci/host0/2/0 is the first PCI function on the third device. As you can see from the screenshot, by reading an object itself, you can find out what an object supports and how to interact with it.

Latest Screenshot

This screenshot shows the new Taskbar app that lists open applications and highlights the app with input focus. It also shows the Transcript app which creates structured logs events from the EventSystem, and allows you to filter the logs using a Gemini expression.


As Saturn is still in its very early stages, there are no releases yet.


Saturn is currently undergoing a major overhaul and thus isn't runnable, but the build system has now been improved to the point where user builds are possible. This section is just for reference for the time being.


  • clang >= 5.0
  • svn
  • yasm >= 1.3
  • cmake >= 3.11
  • patch >= 2.7.6
  • automake exactly 1.15
  • autoconf exactly 2.69
  • grub2-mkrescue


git clone

cd saturn




make qemu


make bochs


make virtualbox


Saturn uses the 3-clause BSD license.


A microkernel based operating system developed from scratch. This repository also includes all Saturn services and applications.





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