Internally, the TROPIX kernel structure is quite different from UNIX. TROPIX has a fully preemptible kernel and many specialized system calls to manipulate and coordinate the execution of real-time processes. Real-time processes coexist with their time-sharing counterparts, but they can run at higher priorities and have many other privileges. Besides its swapper/pager, TROPIX kernel standard processes include a unique dispatcher process per processor. When running in a multiprocessing environment, this scheme greatly facilitates the implementation of different scheduling strategies to be followed by different processors. Fine-grain parallel processing within executing processes is also possible, since TROPIX implements threads at the supervisor level.