OpenBSD/solbourne is an experimental port of OpenBSD to the Solbourne "IDT" family of workstations, built upon the SPARC-compatible Panasonic KAP processor.
The KAP processor used in the IDT systems, albeit using an instruction set similar to the SPARC processors, uses a completely different MMU. Because of this, no free operating system considered running on these Solbourne machines more than a few minutes...
At some point, an S4000 was donated by Mike Nicewonger to Miod Vallat, who then had no excuse not to work on a port. After a few years of procrastination, real work on a port eventually started in march 2005, leading to an initial import in the OpenBSD tree exactly one month later. And work continues...
Currently, only the S4000 system has been tested; but other systems should work, although the L2 cache in the S4000DX systems is not supported yet.
Right now, the system boots single-user, but userland has issues, which are being worked on.