Pilot is an operating system targeted towards personal computers. It is different from Xinu in the following respects:
The kernel routines are encapsulated within Mesa modules and monitors.
The user processes and the kernel share a common virtual memory instead of physical memory.
Programs can be dynamically loaded and linked.
Thus an important disadvantage of this organization is that address spaces are
not protected by the OS.
(This problem is alleviated to some extent by strong type checking in Mesa)
This disadvantage has to be weighed against the advantage of efficient sharing
of information.