What is adder? How it work in computer? Everything you can easily understand by this slide.In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are sometimes used for a sign or for other indications
3. 3
INTRODUCTION
• Digital computers perform various arithmetic operation
Basic arithmetic operation is addition of two binary digits.
• The first three operations produce a sum whose length is
one digit but when the last operation is performed sum is
two digits. The higher bit is called carry. And lower bit is
called sum. This operation is called half adder. The circuit
which performs addition of three bits is a fulladder.
4. 4
ADDERMEANS???
• An adder is a digital circuit that performs additionof
numbers.
• Inprocessor it is used to calculate addresses, table indices,
and similar operations.
• It can be constructed for many numerical representations,
such as binary-coded decimal the most common adders
operate on binary numbers.
6. HALFADDER
The half adder adds two single
binary digits Aand B.
It has two outputs, sum (S) and carry
(C).
Sum=AB’+A’B.
Carry=A*B.
For half-adder design,
an XORgate & an ANDgate
TRUTHTABLE
6
7. FULLADDER
Acombinational circuit that adds 3 input bits to generatea
Sumbit and a Carry bit
Where X,Y,Zare inputs and C& Sareoutputs.
Sum= X+Y+Z.
Cout=XY’+YZ’+ZX’.
TRUTHTABLE
7
X Y Z S C
0 0 0 0 0
0 0 1 1 0
0 1 0 1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 0
