Introduction The number and variety of products that include some form of digital signal processing has grown dramatically over the last five years. DSP has become a key component in many consumer, communications, medical, and indus- trial products. These products use a variety of hardware approaches to implement DSP, ranging from the use of off-the-shelf microprocessors to field-programmable gate arrays (FPGAs) to custom integrated circuits (ICs). Pro- grammable “DSP processors,” a class of microprocessors optimized for DSP, are a popular solution for several rea- sons. In comparison to fixed-function solutions, they have the advantage of potentially being reprogrammed in the field, allowing product upgrades or fixes. They are often more cost-effective (and less risky) than custom hard- ware, particularly for low-volume applications, where the development cost of custom ICs may be prohibitive. And in comparison to other types of microprocessors, DSP processors often have an advantage in terms of speed, cost, and energy efficiency.