A/UX 3.0 is compatible with System 7.
A/UX version 2.1 is not compatible with System 7. The A/UX 2.1 startup
application cannot be launched from a System 7 system. System 7 can't run
in a Macintosh partition under A/UX 2.1.
Users who require A/UX functionality and who want to run System 7 should
upgrade to version 3.0 of A/UX.
A/UX systems are network-compatible with System 7 systems. Users of the
Macintosh partition under A/UX and still running System 6 should upgrade
their LaserWriter drivers to version 7.0. This will make them
printer-compatible with System 7 computers on the network.