Question

The Accumulator of 8085 Microprocessor contains data 89 H. The register D contains data 58H. What will be content of Accumulator in hexadecimal after execution of each of the following instruction dependently (Stepwise i.e. one after another):

1. ADD D
2. DAA
3. CMA
4. SUI B8H

Answer 1

A = 89H, D = 58H

1. ADD D
   89H + 58H = E1H
   A = E1H
2. DAA
   

   Start: A = E1H, AC = 1
   Add 06H:
   E1H + 06H = E7H
    Upper nibble > 9 → add 60H:
   E7H + 60H = 147H

3. CMA
   Complement of 47H = B8H 
   A = B8H
4. SUI B8H
   B8H – B8H = 00H 
   A = 00H