28.2.5. Store Operation Explanation

So, the three codes for LDA store and load add and store are this one. That is the opcode is 000 means that it is a load instruction add means 1000 and 0001 for store. And then this is where you have to load the value is FF0. So, this one is going to be the binary. So, this is your first line of code, 000 very difficult to read and understand therefore, we always keep the memories. So, in this case the instruction size is 4 instruction size is 4 + 12 that is 4 × 4 16 bits. So, it is a 16 bit instruction size that you can also think that a memory in this case is a 16 word bit is the word size.

In computer operations, instructions are represented by unique codes known as opcodes. In this case, three opcodes are introduced: '000' for load operations, '1000' for addition, and '0001' for store commands. Each opcode corresponds to a specific arithmetic operation in programming. The instruction size mentioned is 16 bits, comprised of a 4-bit opcode and 12 bits for the address. This means that each address can point to a single word of memory, simplifying the CPU's task of fetching the required data for operation.

Think of a recipe where each step has a unique number. For example, '001' could mean to prepare the sauce, '1000' could be to boil pasta, and '0001' means to serve the dish. The overall instruction set is like your recipe book, where each instruction (or opcode) helps you achieve a tasty meal, but they need to be understood clearly and sequentially to avoid confusion.

Now, we see stepwise basically what happens, now we will again deal with we have already discussed a similar example beforehand, but now we will see in more depth of the different instructions, even registers and the formats. So, as I told you. So, this is the first instruction to be executed. So, the PC is going to have the value of this one value of the memory location of the first instruction.

When executing a program, the process begins with the Program Counter (PC), which keeps track of the memory address of the instruction that will be executed next. The CPU fetches the instruction from this memory location, available in the memory buffer register. Here, it's mentioned that for a load operation, memory locations are associated with simple instructions, allowing for straightforward processing and execution of commands within the CPU's architecture.

Picture a library where you are looking for the next book to read. The librarian (your PC) helps you find out which book to grab next based on a catalog (the memory address). Each book represents an instruction, and you fetch the book to read (execute it). Just as you rely on the librarian to guide you efficiently, the processor relies on the PC to lead it through the program's instructions.

So, if FF0 this has to be fetched. So, 3 is a load operation sorry 0 is a load operation from where I have to load? So from FF0; that means, it is saying to load the value whatever is available in FF0 the value of 5 to accumulator.

To execute a load instruction, the CPU accesses the specified memory location, such as FF0. This memory location contains a value (for instance, 5), which is loaded into a temporary storage area known as the accumulator. The use of an accumulator is crucial, as it serves as a quick access point for data needed during calculations or further operations by the CPU.

Imagine that FF0 is like a kitchen cabinet that holds a specific ingredient, say sugar (value 5). When you want to make a cake, you need to load your ingredients into a mixing bowl. Here, opening the cabinet represents fetching data from memory, and pouring the sugar into the bowl symbolizes loading that value into the accumulator to use in your recipe.

So, it says that add value of accumulator to whatever value is in FF1. So in fact, again as I told you one word is enough to take a full instruction one address format. So, it will be loaded in the memory buffer register it will go to instruction register decode it and it tells that 8 FF1 means whatever value is in FF1 has to be added to the accumulator that has stored back to the accumulator.

In addition to loading data, a key operation is adding values from different memory locations. In this example, the CPU retrieves the value stored at another location, FF1, and adds it to the current value in the accumulator. Once calculated, the result is stored back in the accumulator, ensuring that the latest data is available for subsequent operations. The decoding step is essential here as it translates the instruction into actionable tasks executed by the CPU.

Think of your baking process again. After measures of sugar are in the bowl, you might decide to add another ingredient, like flour, from FF1. Mixing the two together is like adding them in the CPU's accumulator, resulting in a new batter that's ready to go into the oven (the next step in processing).

Now so, as I told you the next step says that you have to add, this one was the step that you have to add the value of the accumulator to FF1. So, 5 was initially in the accumulator now 7 has been in the memory buffer register, you add these 2 value there is 7 + 5 is 12 that is C and will be again stored back to the accumulator.

After completing the addition operation, the result, in this case 12 (represented as C in hexadecimal), needs to be saved back to a memory location for future reference. This is where the store operation comes into play. The final value in the accumulator is transferred to a specified memory address, in this case, FF2, ensuring that the processed data is retained post-execution.

Once you finish baking your cake batter (12), you pour the batter into a baking pan (FF2) to store it until it’s ready for baking. The instruction to store the value in memory is analogous to placing your cake in the oven, where it will bake and be transformed into a finished product, just as your data is committed to memory for future processes.

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