Ace Test Series: CO & Architecture - Addressing Modes

Question

Given answer is A. I am doubtful between A and B why not B is faster than A. Please explain

Answer 1

Think what would take more time, a register access or a memory access? Register Addressing Mode will have the operand in the specified Register, while in Absolute Addressing mode, the operand will be in the memory, the location of memory cell is in the instruction.

Answer 2

(c) and (d) option cannot be answer becoz if they are compared with above two option than both c and d option are slow (i,e take more time ) so they can be neglected now come to (a) option as register addressing in register addressing all operand are present in register itself and after computation we store result in register itself  also accessing of register is much faster than than accessing the memory location ..one such common example is RISC processor which consists  of lots of  register in which we can store the operands  and because of this need of addressing mode is less, RISC proceesor is costlier because of these registers only, where as CISC processor it is not fast becoz less use of register and more addressing mode .
in (b) option absolute addressing  there we have address in the instruction so with the helo of address we can fetch operand from memormy which take time as compared to register accessing.. so (a) option true

Answer 3

a) register AM----> One register refrence .

b) Absulete AM ---> One mem refrence.

c) reg indirect AM ---> One reg refrence + 1 mem refrence

d) Mem indirect AM -----> 2 Mem refrence .
 
So, option a is true.