HelenOS is a microkernel-based multiserver operating system designed from scratch. It decomposes key operating system functionality into many isolated, intensively communicating server processes that reside entirely in user space. HelenOS thus provides a computing environment that has several
... [More] virtues, such as flexibility, increased robustness, well defined explicit interfaces and reduced complexity of individual components as compared to other operating systems. HelenOS runs on seven different processor architectures, ranging from a 32-bit uniprocessor little-endian ARMv4 to a 64-bit multicore big-endian UltraSPARC T1. [Less]
The GNU Hurd is the GNU project's replacement for the Unix kernel. The Hurd is a collection of servers that run on the Mach microkernel to implement file systems, network protocols, file access control, and other features that are implemented by the Unix kernel or similar kernels (such as Linux).