TABLE OF CONTENTS Juha P. Kylli inen, Tapani Ahonen, and Jari Nurmi
Tampere University of Technology
As a starting point for the exploration of embedded processor architectures, we describe a general-purpose embedded processor core called COFFEE RISC. The reasoning behind its development and the design decisions made are discussed throughout the chapter. Application and application domain-specific issues will be treated in the following chapters.
The complexity of processor architectures varies from multi-million gate designs to designs with a few tens of thousands of gates. Power consumption varies from milliwatt range to hundreds of watts. In order to set the scope for comparison, we need to classify processors and define what we mean by a processor core in this context. Processors targeted to personal computers and mainframe computers form a class with similar requirements. Computing performance and hardware support for operating systems are key requirements in that class whereas power consumption has not been an issue in the past but because of increasing power densities has become a major performance limiting concern.
Processors targeted to embedded systems belong to another class. Embedded systems are products other than general-purpose computing machines. Processors in such systems are used to implement certain functionality of a product, the capabilities of the processor are not important to the user as long as the product fulfils certain requirements. Some level of performance is needed and usually a processor which has just enough performance, but no more, is selected. Especially in battery operated mobile devices, it is essential to select...
