This text is intended to provide practical reference to mechanisms typically described with a more academic slant. It provides a survey of design styles in use in industry, specifically in the high speed microprocessor design community. Logic circuit structures, I/O and interface, clocking, and timing schemes are reviewed and described. Characteristics, sensitivities and idiosyncrasies of each are highlighted. The text also pulls together and explains contributors to performance variability that are associated with process, applications conditions and design. Rules of thumb and practical references are offered. Each of the general circuit families is then analyzed for its sensitivity and response to this variability.