As noted in Chapter 1, an important feature of real-time embedded systems is the concept of determinism. The traditional definition of this term is based on the assumption that for each system state and each set of inputs, a unique set of outputs and next state of the system can be determined. However, we strengthen the definition of determinism for real-time embedded systems by requiring that the time necessary to process any task is predictable. In particular, we are less concerned with average response time than we are with worst-case response time. For example, we must be able to guarantee the worstcase response time for each system call in order for a real-time embedded system to be deterministic. In other words, simply obtaining the correct answer is not adequate. We must get the right answer within a specified time frame.