A new operating system now targets the Z80, and it is not a port or a fork. NostOS is a clean-slate design for classic eight-bit hardware by Scott Baker, built to explore what a structured, modern software stack can look like on a processor more associated with hobby kits and legacy boards than with fresh kernels.

Instead of cloning CP slash M semantics, NostOS defines its own process model with cooperative multitasking, a simple memory management layer and a message passing interface. System calls expose low-level control of I slash O and interrupt vectors while still enforcing basic process isolation. That gives the platform a clearer abstraction boundary than the ad hoc monitor programs and bootloaders that typically sit on bare Z80 silicon.

The kernel is intentionally compact, written in assembly with carefully profiled code paths to keep instruction throughput and latency predictable on limited clock speeds. Around it, Baker is assembling a toolchain that includes a cross assembler, a linker and utilities for filesystem image generation, so that software development can happen on contemporary machines while still targeting the vintage bus. The project positions the Z80 not as a museum piece but as a live testbed for operating system design on constrained architectures.