Logic gates

Abstract

Take a simple, everyday thing like a coffee and soup vending-machine. Before it delivers a cup of coffee, two things must happen: (i) some money must have been put in; and (ii) the button for ‘coffee’ must have been pressed. We can write down the requirement as

$${\bf{mony}}\,{\bf{and}}\,{\bf{coffee}}\;{\bf<Emphasis Type="BoldUnderline">tton</Emphasis>}\;{\bf{=}}\;{\bf{coffee}}$$

and represent this diagrammatically —see Figure 19.1.