Full Adder Chip

Abstraction and Implementation of Full Adder Chip in Hardware Design Language and Java™.

Full Adder Chip

Full Adder chip is used to add 3-bits.

Chip name: FullAdder
Inputs: a, b, c
Outputs: sum, carry
Function: sum = LSB of a + b + c
          carry = MSB of a + b + c

Abstraction of Full Adder Chip - Representation and Truth Table

Implementation of Full Adder Chip in HDL

The function in the above abstraction can help in the implementation of Full Adder Chip.

You can use the Half Adder Chip you've built earlier.l

sum = a XOR b XOR c

carry = (a AND b) OR (b AND c) OR (c AND a)

CHIP FullAdder {
    IN a, b, c;  // 1-bit inputs
    OUT sum,     // Right bit of a + b + c
        carry;   // Left bit of a + b + c

    PARTS:
    HalfAdder(a=a, b=b, sum=sumab, carry=carryab);
    HalfAdder(a=sumab, b=c, sum=sum, carry=temp);
    Or(a=temp, b=carryab, out=carry);
}

Implementation of Full Adder Chip in Java™

Similar to the Implementation in HDL

package CombChips;

class FullAdder_Gate extends HalfAdder_Gate {

    protected static int[] FullAdder(int a, int b, int c) {
        int[] out = new int[2];

        int[] ab = HalfAdder(a, b);
        int[] temp = HalfAdder(ab[0], c);
        int carry = Or_Gate.Or(temp[1], ab[1]);

        out[0] = temp[0];
        out[1] = carry;

        return out;
    }
}