Welcome to OS/Z!

OS/Z is a modern, effective, and scalable Operating System. It's aim is to be small, elegant, portable and to handle enormous amounts of data in a user friendly way.

CC-by-nc-saAlthough OS/Z is Open Source, it's not a Free Software! Licensed under CC-by-nc-sa.


Only a very small portion of the OS is running with supervisor privileges. Everything else is separated and communicates through a secure, effective message queue.


Currently it supports Intel x86_64 and ARM AArch64, but it's easy to port OS/Z to new platforms. Assembly is kept minimal, most of the source is written in ANSI C.


OS/Z was not designed by an English only speaker, so multilingual was always a goal. Internal character representation therefore is UTF-8 throughout the system.


It was designed with scalability in mind. Most of the defines in POSIX limits.h are meaningless here. No limit on tasks, and can handle disks up to Yottabytes.

Easy to use

  • Single installer image boots on BIOS, UEFI and Raspberry Pi 3.
  • Simple configuration file for tuning.
  • Consistent user interface for applications.
  • GNU or LLVM toolchain, dependence-free Makefile rules for compilation.
  • Straightforward, POSIXish API.
  • Built-in debugger and serial debug console.


  • Only the core is running with supervisor privileges, no more than 6000 SLoC.
  • The core does not store any sensitive data, and uses a separate stack.
  • System services are running in user space, just like any other application.
  • Messages are verified by the core.
  • OS/Z utilizes Access Control Lists instead of POSIX groups.
  • Extended file permissions.


Hardware Requirements

  • 10 Mb free disk space
  • 32 Mb RAM
  • 800 x 600 / ARGB display
  • 64 bit IBM PC Compatible - or - Raspberry Pi 3
  • Supported devices