1.12 Circuits
Consider the expression maximum(2, 1 + round(x)),
where maximum is the function we saw earlier in this chapter, and round
rounds a number to the nearest integer. For example, round(1.3) equals
1. Figure 1.10 shows how processing flows as we evaluate the
expression.
To fix terminology, we can call this a function application
circuit. When we draw it like this, we call maximum,
round, and “+” functions, operations, or
gates.
The maximum and “+” gates each take two
inputs and have one output. The round gate has one input and one output. In
general, round is not reversible: you cannot go from the output answer it
produced to its input.
Going to their lowest level, classical computer processors manipulate bits using logic operators. These are also...
