1 - Real-time Computing

Abstract

This chapter gives an introduction to the topic of real-time computer systems. It aims to present the basic principles and concepts associated with the design and utilization of these systems. We will provide a description of the various representative classes of real-time applications according to their time constraints, and we will examine the consequences of violating these constraints both on the system itself and on the environment that it controls. We will also discuss the way that these real-time systems can be scheduled to adapt to the process that they control while meeting the necessary time constraints. Using a few illustrative examples from avionics, multimedia and medicine, we will gain an explicit view of the link between the functional specifications of these applications and their temporal constraints. We will then move on to a discussion of the specific details of real-time operating systems from the perspective of task management, memory management and interrupt handling. The chapter ends with the presentation of a few examples of real-time operating systems, with a special focus on those that are particularly relevant in the context of embedded systems.