MenuetOS is an operating system with a monolithic preemptive, real-time kernel written in FASM assembly language.

[2] The 64-bit MenuetOS, often referred to as Menuet 64, remains a platform for learning 64-bit assembly language programming.

The 64-bit Menuet is distributed without charge for personal and educational use only, but without the source code, and the license includes a clause that prohibits disassembly.

The biggest single effort towards high-level language support is Jarek Pelczar's work in porting C libraries to Menuet.

Several distributions of the 32-bit GPL MenuetOS still exist, including translations in Russian, Chinese, Czech, and Serbian.