Why Some Nordic Programmers Build Entire OSes in Assembly – The Story of MenuetOS

In the Nordic region, programmers are known for tackling ambitious hobby projects, from Linus Torvalds' Linux to Andreas Kling's SerenityOS. This article focuses on another remarkable effort: MenuetOS, an operating system written entirely in x86 assembly by Finnish developer Ville M. Turjanmaa.

History and Development Timeline

Turjanmaa began the project around the year 2000, working alone for fifteen years before releasing the first stable version (1.0). Subsequent updates followed, with versions 1.02, 1.05, 1.15, 1.21, and the most recent 1.51 released in 2024, reflecting continuous refinement over more than two decades.

Technical Characteristics

MenuetOS is notable for being written completely in assembly language. The smallest bootable image fits on a 1.44 MB floppy disk, and on a 200 MHz Intel Pentium MMX the system boots in about five seconds. Despite its tiny footprint, it includes a kernel, TCP/IP stack, graphical user interface, file manager, text editor, drawing tools, and even a classic Snake game.

Assembly‑Based TCP/IP API

The operating system provides a low‑level socket API written in assembly. An example of opening a TCP socket is shown below:

rax = 53
rbx = 5
rcx = local port
rdx = remote port
rsi = remote ip address (in internet byte order)
rdi = mode : SOCKET_PASSIVE or SOCKET_ACTIVE (defined in stack.inc)
The socket number allocated is returned in rax.

All drivers—including libc, network, graphics, and sound—are also implemented in assembly, demonstrating the project's commitment to a pure low‑level codebase.

Performance and Compatibility

MenuetOS can run classic PC games such as Quake and Doom, proving that its assembly implementation delivers sufficient performance and compatibility for demanding applications. Turjanmaa observed that rewriting C/C++ components in assembly can yield a 10 %–40 % speed improvement.

Pros, Cons, and Cultural Context

While the all‑assembly approach results in impressive size and speed, it also makes the codebase difficult to read and maintain; even a simple "Hello World" requires many lines of low‑level instructions. Nevertheless, the project thrives because it is driven by pure curiosity and passion rather than commercial incentives. This environment, where developers can work without profit pressure, is cited as a key factor behind many Nordic technological breakthroughs.

Conclusion

MenuetOS exemplifies how a dedicated individual can create a fully functional operating system from scratch using only assembly, achieving a tiny footprint, rapid boot time, and the ability to run demanding software. Its existence highlights the unique Nordic culture that encourages deep technical exploration without regard for immediate financial gain.