31.3.3. Indirect Addressing Mode Example

So, what is this I am effectively trying to do? So, in this case register 𝑅5 will be 𝑅5 plus what is the content of the memory location how can you find out if whatever is 𝑅1 will be added to the content of the memory location how the memory location is calculated it is content of 𝑅1 + 1.

In indirect addressing mode, the data you want to operate on is found at a memory location pointed to by another register. In this specific case, register R5 will hold its current value plus the content found at a memory location determined by the value in register R1 plus an offset of 1.

Think of it as having a box (R5) that contains money. But instead of just adding money directly to that box, you first have to check another box (R1) to see how much extra money you should add, plus $1 from your allowance. You open the second box, see the amount, add one, then go back to the first box and make your increase.

So, initially they are assuming that 𝑅1 is having the value of 1 and 𝑅5 has the value of 0 that is 𝑅5 is reset.

At the start, register R1 is set to 1, which is important because it helps determine the memory address we are accessing. Register R5 is initialized to 0, meaning it starts with no value before any operation. This setup allows us to clearly see the effect of our operations as we progress.

Imagine starting a savings account (R5) with $0. Your friend gives you a$1 bill (this represents the value in R1) to go check what is stored in their bank account. Your account starts from zero, so whatever you find is what will be added to zero.

So, the instruction takes the address 1 and adds to the content of 𝑅1. So, the content of 𝑅1 and 𝑅2 both have 0. So initially both of them has 0 value so that is this 1 will be added to the content of 𝑅1. So, 𝑅1 is having a value 0. 0 + 1 is 1.

The effective address is calculated by taking the initial value in R1 (which is 1) and using that to find our data. Here, zeroes in R1 and R2 mean no additional value is added when calculating the actual memory address, which simplifies our reference.

It's like having a total bank balance of $0. With your friend's gift of$1, your balance changes to $1, which now tells you how much you can move or invest from your initial position.

So, whatever will be the content will be added with 0 that is the content of R5 and it will be stored over here. Next what you will do you will increment the value of the register number 𝑅1.

Now that we have identified the right memory location, we take the value stored there, which had no impact on R5 before. After identifying and adding to R5, we update R1 by incrementing it, moving to the next element in the memory sequence.

Imagine you have found some money in your friend's account using the $1 check; now you take that money and deposit it into your account. After that, you remember to check another friend's account (increment R1) for any additional money.

The index is actually keeping on incrementing by 1, 2, 3, 4, 5, 6 and it is and that continuously first memory first array location, second array value, third array value...

The logic continues similarly: With every iteration, the index increment allows the program to access the next memory location, adding new values iteratively to R5. This is a key feature of indirect addressing as it allows for dynamic memory access without needing to hard-code specific locations.

You keep visiting your friends consecutively—first checking one friend's account for $1 added to your total, then your next friend for another amount, and so forth, incrementing where you check each time until you've visited them all.

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