<A HREF="http://www.qnx.com/">QNX</A>
is a an effective, scalable, _(POSIX) emulation capable, message passing, _(microkernel) based, distributable, _(real-time)  *(OS)(_(RTOS)) that has proven successful in this embedded market and/or on x86 systems.

See their <A HREF="http://www.qnx.com/developer/docs/">QNX Dcumentation</A>.