Half Adder
 
A
B
SUM
CARRY
0
0
0
0
0
1
1
0
1
0
1
0
1
1
0
1
FIGURE 3    Truth table and block diagram for a Half Adder circuit.
 
    The basic difference between half and full adder is that a half adder has only two inputs. Therefore a half adder cannot recognize a carry input. However, both half and full adders generate a SUM and a CARRY output.
FIGURE 4    Circuitry for a half adder.
The 74LS83 4 bit parallel adder chip.

    The 74LS83 4 bit parallel adder chip. The 74LS83 is a 4 bit parallel adder IC chip. This MSI chip can add two 4 bit binary numbers (A4A3A2A1 and B4B3B2B1) together. The adder chip outputs a 5 bit sum (C4E4E3E2E1). There is also a carry input (CO) available that ca be used to connect multiple 74LS83 chips together for larger adder applications.
 

FIGURE 5    74LS83 4 bit parallel adder chip.