RK0 is a lean yet feature-rich, highly deterministic Real-Time Kernel for deeply embedded systems.
Current Version: 0.74.0-dev (ARMv6/7-M)
The design distinction is its interaction-oriented service model.
RK0ish application code reads as a set of well-defined interactions between visible concurrent units (Tasks). The easy-to-reason, real-time-friendly scheduler, along with non-overloaded services, allows execution progress to be easily inferred from the application code, given the stable operational semantics and Real-Time Model that avoid ambiguity. Zero surprises is the goal. The Docbook provides comprehensive design rationale, internals and usage.