In this chapter, we will look first at two classes of commercial medium-scale integrated circuits*—shift registers and counters. We will introduce programmable logic devices with memory to implement more complex problems such as CPLDs and FPGAs.We will then look briefly at two tools for dealing with these larger systems, ASM (Algorithmic State Machine) diagrams and HDL (Hardware Design Languages). Lastly, we will then look at some larger design problems than we could manage in Chapter 7. We will concentrate on synchronous (clocked) systems.