History
A long lineage runs from Bell Labs UNIX, through Mach and NeXTSTEP, into Darwin and the BSDs — and lands here. NextBSD Redux is the latest pickup of work that has changed hands more than once.
AT&T’s Bell Labs builds UNIX — the operating system every system on this timeline ultimately descends from.
UC Berkeley releases the first Berkeley Software Distribution, a set of enhancements layered on AT&T UNIX.
Berkeley ships the Fast File System and TCP/IP networking — storage and networking groundwork that later BSDs, and macOS, would inherit.
CMU develops the Mach microkernel — a message-passing foundation that becomes the kernel core of NeXTSTEP and, later, Darwin.
After leaving Apple, Jobs starts NeXT to build a new generation of workstations and software.
NeXT releases NeXTSTEP — the Mach kernel and BSD userland under an object-oriented application layer. The blueprint NextBSD follows.
The open BSD distributions emerge and carry the Berkeley lineage forward. FreeBSD becomes the base NextBSD builds on.
NeXTSTEP — Mach, BSD, and the Objective-C runtime — comes back to Apple and becomes the foundation of its next operating system.
Apple ships Mac OS X atop Darwin — the Mach kernel fused with BSD userland — the open-source core under every Apple OS since.
The effort to ship Darwin as a standalone, installable operating system ends — leaving the system layer open but homeless.
A sponsored project sets out to bring the Darwin system layer — Mach IPC, launchd, libdispatch, notifyd — onto a FreeBSD base. Joe Maloney contributes to it — EFI and ZFS loader work, release packaging, an i915 graphics update — the first thread running from that effort to this one.
A new macOS-compatible effort starts on a FreeBSD base, pursuing a familiar desktop and app experience.
ravynOS shifts its kernel direction toward XNU.
A new vision based on those earlier efforts.