Consider the Boolean algebra $\backslash ((\backslash \{0,1\backslash \},+,\backslash$cdot$,-)\backslash )$ as in slide $2\mathrm{.}11.$ The Boolean operations,$\backslash (+\backslash$cdot $\backslash )$ and can then be defined by the tables below. Here, the symbol $+$ will read $"$or$"$ instead of "plus", the symbol $\backslash (\backslash$cdot $\backslash )$ will read "and" instead of "dot", and the symbol $-$ will read "not" instead of "bar".

This Boolean algebra is at the basis of circuit design. A computer is made up of a number of circuits. The basic elements of circuits are gates. Typically, there are one or more inputs to a gate, and only one output. Gate inputs are driven by voltages having two nominal values $($e$.$g$.,0$ V and $5$ V $)$; these values are represented by the symbols $0$ and $1$ respectively. The output of a gate also provides two nominal values of voltage only. Common gates are: