A Binary Adder-Subtractor is one that is capable of both the addition and subtraction of binary numbers in one circuit itself. The operation is performed depending on the binary value the control signal holds. The circuit consists of 4 full adders since we are performing operations on 4-bit numbers. There is a control line Cin that holds a binary value of either 0 or 1 which determines that the operation is carried out is addition or subtraction.