Addressing modes

Question

Could you please explain How we can implement indirect addressing mode using Index addressing mode.. and vice versa..??

Comments

Very similar to using pointer for array access and vice versa. Can you give a try?

Answer 1

Direct Index addressing mode – X(R1). Here Effective address of the operand, EA = X + [R1], where [Y] is the content of location Y.

Indirect Index addressing mode – (X(R1)). Here EA = [X + [R1]].

Source: Carl Hamacher, Figure 7.20.

Comments

That’s not directly answering the given question right?

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when the question said, “implement indirect addressing mode using Index addressing mode.. and vice versa..”  I got a bit confused because there is no addressing mode called indirect. But every addressing mode has a direct and an indirect version to it.

like,

direct register addressing mode, EA = R, where R is a register.

indirect register addressing mode EA = [R]

direct absolute mode, EA = LOC, where LOC is a memory location.

indirect absolute mode, EA = [LOC]

So, I just wrote direct and indirect versions of the index addressing mode, where the direct index addressing mode uses the indirect register mode.