Q40,p3,J14. The advantage of _______ is that it can reference memory without paying the price of having a full memory address in the instruction.

(A) Direct addressing

(B) Indexed addressing

(C) Register addressing

(D) Register Indirect addressing .

Answer D

Direct addressing include a 16 bit address as part of instruction.(ex jmp 1000H.)

Register indirect instruction reference memory via a register pair(ex Mov M,C move the contents of C register into memory address stored in H and L register pair. Hence it has no memory address in instruction.

Register addressing specify one of the address A-E,H or L. with these instructions Accumulator is assumed as the second operand. Ex CMP E ( compares the register E with accumulator)

 In Index addressing (Effective address = address + contents of specified index register) For example array starts from a memory location X. first array element is stored at x,and next element of array is stored at X+1 and so on. Which element of the array is to be processed is kept in the index. And effective address is found by adding the subscript of array in X. - (Effective address = address + contents of specified index register) For example array starts from a memory location X. first array element is stored at x,and next element of array is stored at X+1 and so on. Which element of the array is to be processed is kept in the index. And effective address is found by adding the subscript of array in X.