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Question: Design a Mealy machine for a full adder.

 

Answer: At full adder, we add three bits and we get two output sum and carry. We generally categorized binary full adder in two ways:

 

a. Where we got carry b. Where we did not get carry

 

Example:

 

Inputs

Sum (s)

Carry (c)

1+0

1

0

0+0

0

0

0+1

1

0

1+1

0

1

 

Inputs

Sum (s)

Carry (c)

0+1+1

0

1

1+0+1

0

1

0+0+1

1

0

1+1+1

1

1

 

So, we design two states   1. Where we get carry and 2. Where do not get carry

 

 

This carry state c means we got the carry, then again at carry state we process four combinations (00, 01, 10, 11)

 

We start the initial state as NC if we take initial carry = 0    [NC means NO Carry State]

 

 

On the other hand, we start the initial state as c if we take initial carry = 1