28.2. Execution Steps of Instructions

So, the threes 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.

This chunk introduces the binary opcode system used for instructions in a computer system. Each opcode represents a specific instruction: '000' for load, '1000' for add, and '0001' for store. The opcodes are concise, efficient representations of commands that the CPU can understand.

Think of opcodes like the commands you use in a video game. Just like how 'A' might mean 'attack' and 'B' might mean 'block', opcodes are the shortcuts that allow the CPU to perform commands quickly without needing to understand complex phrases.

And then this is where you have to load the value is FF0. So, this one is going to be the binary. So, if somebody erases this and say this is your first line of code, 000 very difficult to read and understand therefore, we always keep the memories.

This chunk highlights the importance of having a memory structure to store instructions and data. When instructions are represented in binary, they can become hard to interpret. The use of memory allows programmers to write more understandable code using mnemonics instead of raw binary.

Imagine trying to read a recipe written in binary numbers rather than using regular words. Keeping a recipe book (memory) allows you to refer to simple instructions (mnemonics) rather than memorizing or deciphering a bunch of numbers.

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 this portion, the size of the instruction is discussed. A 16-bit instruction allows the CPU to handle more complex operations because it can encode both the command and the operand in a single instruction. This efficiency aids in faster processing as more data can be addressed at once.

Consider how a video game console can load higher quality graphics with more bits. Just like a 16-bit console can display more colors and details than an 8-bit one, a 16-bit instruction size allows the CPU to process more complex operations effectively.

In this case you might have taken a longer size. So, maybe 0 FFF and in this case maybe the other part of the other address would have been there.

The text discusses single address instruction formats, referring to instructions that use only one memory address. This simplifies the CPU's task as it highlights a direct path to load or store data. If a two-address format were used, it would complicate the instruction and require additional operations.

Think of ordering pizza: if you have one address to go to (your home), it’s straightforward. But if you need to visit two addresses (your home and a friend’s), it adds complexity to your task. Similarly, single address instructions simplify the execution process for the CPU.

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.

In this section, the process of loading a value from a specific memory address (FF0) into the accumulator is described. The accumulator is a register where intermediate arithmetic and logic results are stored. Loading operations are fundamental to processing as they bring the necessary data into the CPU for manipulation.

Imagine a chef (the CPU) needing an ingredient (the value) from the pantry (memory). The chef goes to the pantry, retrieves the ingredient (loads it into the accumulator), and then can use it in the recipe (perform calculations).

Now what happens is that next you have to store. So, this is the program counter has gone to a third instruction, it is getting loaded over 1FF2 to the instruction register.

This portion details the instruction to store the current value in the accumulator back to a specific memory location (1FF2). Storing results is just as crucial as loading them. The state of the program counter (PC) is updated to point to the next instruction after storing, facilitating seamless instruction execution.

Continuing with the chef analogy, after the chef has finished cooking (processing the data) and has the final dish (value in the accumulator), they then put that dish away in the fridge (store it back in memory) for later use.

Control means what? It’s very simple control means based on the value of some of the jump instruction the value of the PC will be changed.

This section introduces control instructions, which determine the flow of program execution by changing the program counter (PC). Control instructions (like jumps or branches) allow for decision-making in programs, enabling them to react to certain conditions and direct the flow accordingly.

Imagine a maze where at various junctions you must decide which path to take based on certain signs (conditions). The ability to make decisions at these points (or jumps) allows you to navigate through the maze successfully, just like control instructions guide the CPU through a program.

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