14.3.3. Immediate Addressing Mode

The simplest one is the immediate mode. So, we are just saying LOAD R1, 32; that means, the value of 32 constant will be loaded to R1 and we are assuming that this instruction takes a single word. So, in this case the PC has to be incremented by 1.

Immediate addressing mode is a straightforward method where the instruction directly contains the operand (data) to be used. For example, in the instruction 'LOAD R1, 32', the number 32 is the immediate value that will be loaded directly into the register R1. The program counter (PC) will increment afterward to point to the next instruction.

Think of immediate addressing mode like giving a friend a packed lunch with a note that says, 'Eat this.' The lunch itself is the data (operand), and you're giving it directly to them without needing them to go look for it. In this case, the note represents the instruction without additional steps needed to gather the food.

So, what are the steps? So, the first step if you look you know the program counter will be the output it will go to memory address in. So, what does it mean already we have discussed with the figure in the last class.

The execution follows a series of steps: 1) The program counter (PC) value is loaded and read into the memory address register, typically set to read mode. 2) The memory provides the instruction, which is then loaded into the instruction register. 3) Finally, in the instruction register, the immediate value (32) is transferred to R1. This series of operations illustrates the mechanics of how the instruction is fetched and executed in immediate mode.

Imagine you're accessing a recipe on your phone. First, you open the recipe app (PC), then you select a specific recipe (memory address register), and finally, you read the ingredients directly from the screen (instruction register) to start cooking. This process mirrors how immediate addressing allows quick access to data.

For an immediate mode, we just have 4 micro instructions and your job is done. First micro instruction or sequence of control fetch and last one you take the value of the operand from the instruction register and dump it into the respective register.

In immediate addressing mode, the process is efficient with only four micro instructions required: 1) Fetch the instruction using the PC, 2) Increment the PC, 3) Load the instruction into the instruction register, and 4) Transfer the immediate value to the destination register (R1). This compact sequence reveals how immediate addressing minimizes time and resource use in instruction execution.

Consider this like a vending machine: You insert money (PC), choose a drink (fetch the instruction), it dispenses it right away (increment the PC), and you receive your drink (loading the value into R1). The direct way you get your drink illustrates the straightforward nature of immediate addressing.

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