8. Suppose that the following instructions are found at the given locations in memory:

Program counter: 20

Value in memory location 20: 550(LOAD)

Value in memory location 21: 151(ADD)

value in memory location 22: 350(STORE)

:

:

Value in memory location 50: 724

Value in memory location 51: 006

Show the changes of contents of IR, PC, MAR, MDR and A during

(a) Instruction 20

(b) Instruction 21

(c) Instruction 22