A restoration · ipnx Edition 8 Release 1.0

Bell Labs Research Unix,
booted and carried forward.

Eighth Edition — the one with /proc, streams, and the Blit — running on an emulated VAX-11/780 inside a native Mac app, and displayed the way it was meant to be seen: through an emulated DMD 5620.

Download for Mac How it works Source on GitHub

Version 1.0 · macOS 26 or later · Apple silicon · Free · Signed and notarised

Abstract

Research Unix Editions 8, 9 and 10 were written at Bell Laboratories between 1985 and 1989 and never released outside it. They are where /proc, the stream I/O system, the file system switch and a network file system first appeared, and they are what the people who then wrote Plan 9 were using at the time. In March 2017 Alcatel-Lucent stated it would not assert copyright against non-commercial use of them.

This program is what that permission is for. It is not a museum piece behind glass: it is a working Eighth Edition machine that boots in half a minute, keeps its state between launches, mounts your own folders, and reaches the network — on hardware you already own.

It is a real system, and it will tell you so

Not a shell that looks old. The kernel is the one Bell Labs wrote, compiled from the source in this repository by its own compiler, running on a simulated VAX with its own clock, disks and Ethernet card.

The banner is generated at build time from v8/RELEASE, so the machine and the repository can never disagree about which release you are looking at.

$ ipnxfetch
                   christie@ipnx-v8
                   ------------------------------
OS:        ipnx Edition 8 Release 1.0
Host:      VAX-11/780 (emulated)
Kernel:    ipnx Edition 8 Release 1.0 (2026-08-16)
Uptime:    3 mins
Shell:     /bin/sh
Terminal:  dmd
CPU:       VAX-11/780 @ 5 MHz (emulated)
Memory:    8128 KiB

$ ls /n/macos
Applications  Library       Users         Volumes

Output from a booted machine, transcribed exactly.

Section 1

The whole machine, not an impression of one

ipnx runs a VAX-11/780 — the open-simh vax780 simulator, compiled into the app as a library — and boots an unmodified Research Unix kernel on it. Nothing is reimplemented and nothing is shimmed. The kernel schedules, pages and forks inside the emulated machine, so iOS and macOS restrictions on spawning processes or generating code never come near it.

The screen is a second computer. The DMD 5620 was a bitmapped terminal with its own WE32100 processor, and programs were downloaded into it over the serial line. ipnx emulates that too, and joins the two with a virtual wire. It is the 1985 topology exactly: a smart terminal, an RS-232 line, and a headless host at the other end.

Section 2

A system built from its own source

The disk the app ships is not a museum image passed hand to hand. It is built, from the source in this repository, by a world build that Research Unix never had — a staged bootstrap that compiles the toolchain with the tape’s compiler, recompiles the toolchain with itself until the two agree byte for byte, then builds the libraries, the commands and the kernel, lays down a filesystem, and has the result rebuild itself under chroot.

What cannot be built is carried and named: 1,406 paths the tape shipped as machine code with no source — the 5620 binaries, the games, the manual. Everything else has a rule.

Section 3

Connected to the world it never met

Peter Weinberger’s network file system has been compiled into every Research Unix kernel since 1985 and has had nothing to talk to since Datakit was switched off. ipnx gives it a server again, so a folder on your Mac is mounted inside Eighth Edition, read and write, at /n/macos and /n/home.

The machine also reaches the actual Internet. It has an Interlan NI1010 Ethernet card — modelled for the simulator because none existed — and Research Unix’s own TCP/IP, the one built as stream line disciplines that predates the sockets everyone remembers. It resolves names and opens connections.

Where this is going

Eighth Edition is what ships today. It is also the host for the part that has never been done.

Edition 8 · 1985: Shipping. Boots to login: in about thirty seconds, with the 5620, mux, networking and your folders mounted.
Edition 10 · 1989: The restoration. Tenth Edition survives as source only andhas never been booted by anyone. The plan is to cross-build it inside the running Eighth.
Edition 9: Deliberately skipped. What survives of it is a Sun-3 port with no VAX kernel code, so there is nothing there to boot.

Free, and necessarily so

The 2017 statement covers non-commercial use only, so ipnx has no price, no advertising and nothing to buy — not as a policy but as a condition of existing.

Download ipnx.dmg