Anything monolithic, where a single binary executable is run at the start, maybe spawning subprocesses to handle parallel tasks, possibly sharing memory through synching protocols to avoid interlocking.

SOA uses message passing only as the synch mechanism, but sharing memory allows for other strategies with synch primitives such as semaphores or mutexes (with the assumption that collaborating processes run on the same physical machine, or communicate through Remote Procedure Calls).

http://www.composingprograms.com/pages/48-parallel-computing...

https://en.wikipedia.org/wiki/Remote_procedure_call