Subtractors

A digital circuit that does the operation . The operation can be done by negating and then adding it to .

The circuit consists of an inverter and a full adder with C_0 set to 1.

Adder-Subtractor

A digital circuit that can do both addition and subtraction. A control signal is used to switch between the operations.

In the above example, is the control. When , it works as an adder. Otherwise it works as a subtractor.