Question 10.26: Describe serial addition....

In serial addition the two numbers are added one bit at a time, just as they would be added manually. This can be done by using two shift registers, a full-adder and a f l i p-f l o p as shown in Fig. 10.16.

The two first bits are taken from the serial outputs of the shift registers and added. The sum is fed back to the serial input of one shift register (register A in this example) while the carry is stored in the flip-flop. This procedure continues until all bits of the two numbers have been added, when the sum will be stored in the first shift register. If required, a further number may be loaded into the second shift register and added to the sum.