ABSTRACT
An ability to make decisions based on a variety of different factors is crucial to the safe operation of a modern aircraft. It is therefore not surprising that logic systems are widely used in aircraft today. In this chapter we introduce the basic building blocks of digital logic circuits (AND, OR, NAND, NOR, etc.) together with the symbols and truth tables that describe the operation of the most common logic gates.We then show how these gates can be used in simple combinational logic circuits before moving on to introduce bistable devices, counters and shift registers.The chapter concludes with a brief introduction to the two principal technologies used in modern digital logic circuits,TTL and CMOS.
