Several processes per address space?

[Mike Powell]

Has anyone had any experience modifying (some version of) Unix to permit more
than one process in an address space?  I mean real processes, ones that can do
system calls independent of one another.  Personal experiences or pointers to
papers or people would be appreciated.
					Michael L. Powell
					Digital Equipment Corporation
					Western Research Laboratory
					Los Altos, CA  94022
					{decvax,ucbvax}!decwrl!powell
					powell at decwrl