AUXrunner.zip contains a standalone app, based on QEMU, that runs Apple's A/UX operating system. It requires macOS 15 Sequoia or later. I built the A/UX setup using this guide and with extensive, essential help from Cat_7 in this thread at Emaculation.com. (Updated 21 July 2026.)
To use it, simply launch the app. If you hold down the Option key while launching it, it will offer to open the command file inside it and also open a Finder window on the folder that contains the files.
You can ftp to the A/UX system by starting an ftp session from the host system; set the ftp address as the same network address used by the Mac computer host; set the username and password to "user" and "password", and (very important) set the port to 2121 (not 21).
When you shut down A/UX from the A/UX menu, do not shut down QEMU until the "You may now switch off your Macintosh safely" message appears. At this point, depending on the QEMU version that is running, you may need to press Ctrl-Opt-g to release the mouse, and then Cmd-Q to quit QEMU, or it may be enough to press Cmd-Q without releasing the mouse.
By default, the app opens to the root account, which has no password. The documentation (see below) explains how to log in to a menu that asks for a username and password, and to log in to different kinds of sessions. The setup supplied here has a root account and a user acount named "user" with the password "password". The root password is empty.
The app is notarized by Apple, and should start without problems after you respond to a prompt from macOS. If, however, it won't start, do this. Open a terminal; type this string into the terminal window:
sudo xattr -rc
followed by a space (the space is essential). Then drag the app into the terminal window so that its path appears on the command line. Press return to run the command. The app should now start.
Display two windows: An alternate version of QEMU included in the app opens two windows instead of one, corresponding to two hardware screens. To enable this, change the name of the app so that it includes the string "screens" (e.g. AUXrunner-screens). The same A/UX system will open, but on two screens, which the app positions side by side and centers on your display. The left window is screen 0, the one that carries the A/UX menu bar, and it starts out in front. Both versions are now universal apps; neither requires Rosetta 2. You can make the two-window version the default by editing the AppleScript; if you know how to edit AppleScript, this will be easy.
Permission needed for the two-window version: Positioning the two windows requires Accessibility permission. The first time you launch the app with "screens" in its name, macOS should ask for it; move the slider to grant permission, then quit the app and launch it again. If macOS does not ask, open System Settings > Privacy & Security > Accessibility, click the + button, and add the app yourself. A/UX runs normally without this permission — the two windows will simply open on top of each other instead of side by side.
If the windows stop moving into place after you modify the app in any way — including using the Option-key command described above to edit the command file inside it — the Accessibility permission has probably gone stale, because macOS ties that permission to the app's digital signature. Open System Settings > Privacy & Security > Accessibility, remove the app from the list with the - button, add it again with the + button, and relaunch.
Launch the X11 server: To launch X11, open the root folder (/) from the desktop, then the mac folder, then the MacX folder, and launch MacX.
A/UX documentation from Apple:
A full set of manuals may be found on this archive site.
Edward Mendelson (edward [dot] mendelson [at] columbia [dot] edu)