It uses the loader to do this. It does this on receiving a timer interrupt. An interrupt service routine handles the timer interrupt. An interrupt service routine handles the system call. The process itself can decide to exit, by making a system call, or the process can be abnormally terminated in a number of ways.
Processes come out of the job queue when they are finished.
Be sure to describe the process state of the process at every point. Be sure to describe what parts of the operating system move the process from one state to another or from one queue to another. PCB0's process state is new . PCB0's process state is ready . PCB0's process state is running .