PROCESSOR DESIGN FOR PORTABLE SYSTEMS

Processors used in portable systems must provide highly energy-efficie nt operation, due to the importance of battery weight and size, withou t compromising high performance when the user requires it. The user-de pendent modes of operation of a processor in portable systems are desc ribed and separate metrics for energy efficiency for each of them are found to be required. A variety of well known low-power techniques are re-evaluated against these metrics and in some cases are not found to be appropriate leading to a set of energy-efficient design principles . Also, the importance of idle energy reduction and the joint optimiza tion of hardware and software will be examined for achieving the ultim ate in low-energy, high-performance design.