Introduction

As the prices of microprocessor chips have fallen, they have increasingly become standard, ‘off the shelf’ components and find their way into a very large proportion of modern electronic equipment and instrumentation. A microprocessor built into a piece of equipment, rather than providing the central processor for a general-purpose microcomputer, is said to be ‘dedicated’ or ‘embedded’. The software which controls such a device is necessarily specialised and is usually called ‘firmware’. This term will be used throughout this book. Strictly speaking, firmware is code which has been placed in non-volatile, read-only memory (ROM) chips, which are built into the circuit with the microprocessor, but this is not always the case, as alternative memory schemes are possible. The various techniques associated with the development of firmware are the subject of this book.