OpenBSD/sparc OSREV is brought to you by the same people who did the first
free BSD sparc port (based on Chris Torek's 4.4BSD work).  Many more sparc
models and devices are now supported.

In addition to providing SunOS 4.1 compatibility, OpenBSD OSREV will
also run some number of SunOS 5 (SVR4) executables in binary emulation mode.