Two ways for implementing a serial adder ( A + B ) is shown in Section 6.2. It is necess...

Two ways for implementing a serial adder ( A + B ) is shown in Section 6.2. It is necessary to modify the circuits to convert them to serial subtractors ( A - B ).

(a) Using the circuit of Fig. 6.5 , show the changes needed to perform A + 2’s complement of B . (HDL—see Problem 6.35(h).)

(b) *Using the circuit of Fig. 6.6 , show the changes needed by modifying Table 6.2 from an adder to a subtractor circuit. (See Problem 4.12). (HDL—see Problem 6.35(i).)