NLTSS was a capability-based client–server system. The two primary servers were the file server and the process server. The file server was a process privileged to be trusted by the drivers for local storage (disk storage,) and the process server was a process privileged to be trusted by the processor driver (software that switched time sharing control between processes in the "alternator", handled interrupts for processes besides the "communicate" call, provided access to memory and process state for the process server, etc.).