NetBSD/mips and
NetBSD/vax architectures can run Risc ULTRIX and VAX ULTRIX executables, respectively. However, you have to worry about the legal issues of ensuring that you have a right to use any ULTRIX binaries on your machine.
Most executables will work. The exceptions include programs that use proprietary, ULTRIX-specific features (LAT, CI support, DECnet support) and various system calls,
ioctl()'s, or ULTRIX kernel semantics that are difficult to emulate (e.g. ULTRIX packetfilter) or buggy (e.g. ULTRIX NIS).
All ULTRIX executables are static, so no shared libraries are required for ULTRIX compatibility. However, ULTRIX is based on a
4.3BSD alpha release. ULTRIX commands and libraries are often much older than their
NetBSD or even SunOS 4.x equivalents, and may require incompatible configuration files.