In this work the proprietary architectures and processes of the assortment of CPLDs and FPGAs on the market are detailed in order to provide the insight necessary for selecting the appropriate device. It describes the design flow for a CPLD-based or FPGA-based project so the reader can properly plan the necessary development tools, schedule, and resources. A detailed description of the design, simulation, and testing issues that arise when designing a CPLD or FPGA follows.