Managed Operating System Alliance Project
C# Other
Latest commit bdb4eeb Jan 23, 2017 @tgiphil tgiphil committed on GitHub Merge pull request #360 from tgiphil/master
Fixed inlining with delegate method
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Demos - Updated demo scripts Jan 14, 2017
.editorconfig - Added .editorconfig (see Dec 25, 2014
Compile.bat - Changed compile.bat script to use debug build Nov 22, 2015
Credits.txt - Updated contributors Feb 15, 2015
LICENSE.txt - Updated LICENSE file Aug 7, 2014
Launcher.bat - Fixed CIL.Ldc transformation Sep 20, 2016

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MOSA is an open source software project aiming to create a high quality, cross-platform, optimizing .NET compiler designed specifically to support a managed operating system based on the .NET framework.

The MOSA project consists of:

  • Compiler - a high quality, multithreaded, cross-platform, optimizing .NET compiler.
  • Kernel - a small, micro-kernel operating system.
  • Device Drivers Framework - a modular, device drivers framework and device drivers.

Read our Frequently Asked Questions for more information about this project.

Current Status

The MOSA compiler supports:

  • almost all non-object oriented code (arithmetic, assignment, bitwise logic, bitwise shifts, boolean logic, conditional evaluation, equality testing, calling functions, increment and decrement, member selection, object size, order relations, reference and dereference, sequencing, and subexpression grouping),
  • basic object oriented code (such as new operator, member methods and virtual methods),
  • basic type conversion (implicit type and explicit type conversion on primitives types and "is" and "as" operators),
  • generic code (example, List), and
  • delegates (static and non-static) and with optional parameters.
  • exception handling (try, finally, and catch code blocks)

Getting Started


The MOSA project is available as a zip download or via git:

git clone


You will also need the following prerequisites:


Install any Visual Studio version 2015 or newer.

All editions are supported including the fully-featured free Community Edition.

The EditorConfig plugin is recommended for MOSA contributors.


Install Mono and Qemu.

The minimum supported version of Mono is 4.4, this is not in some distributions repositories and must be added manually. A tutorial on how to do this can be found at the following URL.

If using the APT package manager you can use the following command to quickly set up QEMU and Mono

sudo apt-get -y install mono-devel qemu


Install Mono and Qemu.



Double click on the "Compile.bat" script in the root directory to compile all the tools, sample kernels, and demos.

Next double click on the "Launcher.bat" script, which will bring up the MOSA Launcher tool (screenshot below) that can:

  • Compile the operating system
  • Create a virtual disk image, with the compiled binary and boot loader
  • Launch a virtual machine instance (QEMU by default)

By default, the CoolWorld operating system demo is pre-selected. Click the "Compile and Run" button to compile and launch the demo.

MOSA Launcher

MOSA CoolWorld Demo

Join the Discussion

Join us on Gitter chat. This is the most interactive way to connect to MOSA's development team.


MOSA is licensed under the New BSD License.