half adder and full adder
TRANSCRIPT
HALF ADDER & FULL ADDER
BYSUMAN SUKHDEVE & DURGA NAGALWADE
B.SC. III YEARFROM
JAWAHARLAL NEHRU COLLEGE ,WADI, NAGPUR-23
ADDER An adder is a digital logic circuit in electronics that implements addition of numbers. In many computers and other types of processors, adders are used to calculate addresses, similar operations and also in other parts of the processors. These can be built for many numerical representations like binary coded decimal. An adder is a digital circuit that performs addition of numbers. Adders are classified into two types: half adder and full adder.
Half adderHalf adder is a combinational arithmetic circuit that adds two numbers and produces a sum bit (S) and carry bit (C) as the output.If A and B are the input bits, then sum bit (S) is the X-OR of A and B and the carry bit (C) will be the AND of A and B.From this it is clear that a half adder circuit can be easily constructed using one X-OR gate and one AND gate.BOOLEAN EQUATION IS
FOR SUM : S = B + A OR S = A B FOR CARRY : C = A . B
x y c s
0 0 0 0
0 1 0 1
1 0 0 1
1 1 1 0
INPUT OUTPUT
HALF ADDER CIRCUIT & TRUTH TABLE
THE MAIN DRAWBACK OF HALF ADDER IS THAT WE CAN’T ADD THREE BINARY BITS AT A TIME .
THIS DRAWBACK CAN BE OVERCOME IN FULL ADDER
FULL ADDERA full adder adds binary numbers and accounts for values carried in as well as out.The full-adder circuit adds three binary numbers as input A , B , Cin and outputs two one-bit binary numbers, a sum (S) and a carry (Cout). A full adder can be constructed from two half adders by connecting A and B to the input of one half adder, connecting the sum from that to an input to the second adder, connecting Ci to the other input and OR the two carry outputs.BOOLEAN EQUATION IS
FOR SUM : S = FOR CARRY : C= ABCi
x y C in C out s
0 0 0 0 0
0 0 1 0 1
0 1 0 0 1
0 1 1 1 0
1 0 0 0 1
1 0 1 1 0
1 1 0 1 0
1 1 1 1 1
INPUT CARRY IN OUTPUT
FULL ADDER CIRCUIT & TRUTH TABLE