The Machine Emulator
The Machine Emulator (tme), like simh, provides a general purpose emulation framework. In particular, it has support for Motorola 68k and SPARC processors, with associated hardware as in Sun-2, Sun-3 and Sun-4 series computers. It can run NetBSD and SunOS for Sun-2 and Sun-3 machines.
It seems to be very hard to get to run except on a NetBSD host, so you may end up running it inside emulation. You might want to look into Qemu to emulate a nice x86 host environment for this.
- tme's site - http://people.csail.mit.edu/fredette/tme/
- prebuilt setups for NetBSD and SunOS emulated environments - http://www.retrocomputinggeek.com/retrowiki/tme/%5C%20%20title=%5Ctme