Binary Parallel Adder/Subtractor

The addition and subtraction operations can be done using an Adder-Subtractor circuit. The figure shows the logic diagram of a 4-bit Adder-Subtractor circuit.

The circuit has a mode control signal M which determines if the circuit is to operate as an adder or a subtractor. 

Carry Look Ahead Adder

In ripple carry adders, the carry propagation time is the major speed limiting factor.

Most other arithmetic operations, e.g. multiplication and division are implemented using several add/subtract steps. Thus, improving the speed of addition will improve the speed of all other arithmetic operations.

Half Adder Circuit

Half adder circuit is essential circuit for computer hardware components. The device which can calculate some integer or floating point wants half adder circuit. It is used for performing mathematical calculation in hardware. In computer, calculator and other counting device use half adder. It is the great invention for the scientists to sum the numbers easily. It consists of a XOR gate and two input pin and output sum and carry. Numbers of n bit are connected serially to add numbers.

Truth Table 

Input A	Input B	Output C	Output S
0	0	0	0
0	1	0	1
1	0	0	1
1	1	1	0