This chapter presents that high performance embedded computing (HPEC) software architectures and evaluation metrics. A canonical HPEC application is used to illustrate basic concepts. The chapter discusses different types of parallelism are reviewed, and performance analysis techniques. It presents a typical programmable multicomputer and explores the performance trade-offs of different parallel mappings on this computer using key system performance metrics. HPEC systems are amongst the most challenging systems in the world to build. Synthetic Aperture Radar (SAR) is one of the most common modes in a radar system and one of the most computationally stressing to implement. Often the first step in the development of a system is to produce a rough estimate of how many processors will be needed. The parallel opportunities at each stage of the calculation discussed in the previous section show that there are many different ways to exploit parallelism in this application. The chapter concludes with a discussion of the impact of different software implementations approaches.