This book reflects the considerable current industrial interest and investment in process control systems. The use of computer systems in process control can provide great benefits, and it is estimated that efficiency can be increased by up to 30%. It is not surprising, therefore, that there have been considerable efforts by system designers and users to introduce and use such systems. Process hardware is integrated into a complete production system through data processing. It is for this purpose that technical specialists (e. g. electrical, mechanical, electronics, communication and process engineers and program­ mers) are involved in data processing. The scope of this book is therefore to assist in the selection of computer hardware and software that match the functional specification of the data processing component of a particular system. The principal points covered in this book are set out below. Part One: Production process hardware for a standard process is outlined and the information processing hardware is described. Large mechanical process hardware and process information devices (e. g. sensors and control elements involved in the process) create a coherent production unit, or system, which can be the control unit (i. e. the basic process unit). The hardware processes are described and the mathematics explained. This enables the application of control laws in order to linearize the process about its working point, as well as a stratification of process control tasks.