Circuits: black box

"Thinking outside the box."

Abstraction: sometimes we need to see the details of how a circuit is built

Other times, we only need to know what it does

Black box: represents only inputs and outputs

Example:

Conventions:

Data inputs are circled: x, y

Control inputs are written in triangles

or trapezoids: c

Outputs are squared: z0, z1

Hardwired 0's and 1's can be written as

just 0's and 1's (no shape)