All things in all posts will help you visualize about the way that computers work generally. Note that it is not the real structure of modern computers, but the way that modern computers work is nearly the same as in my posts. I am sure that if you understand about the way that computers work in my posts, you will easy to learn about all fields of computer afterward. Thank you !!!
In the previous post about the way that fetching instructions, we have known that the instructions are binary codes in essence. This thing is easy to understand because the only thing that is transported on the bus is the byte. So, we can call these instructions “instruction code”. Every instruction code must have a specific meaning for their functions. Look at the diagram below to recall the way fetching instruction:
How can a computer know the meaning of the instruction code? The answer is the way that we use gates and the way we wire gates in the control unit will determine the function of the instruction. So, one instruction code will be assigned a meaning, then that instruction code will be set that meaning by gates and wires in the control unit.
You can see that the instruction code will be assigned a meaning first and that meaning is invented by an organization. It is similar to characters in the ASCII. Of course, you can also assign a meaning for an instruction code and then set up gates and wires for that instruction code by yourself. But nobody uses that instruction code, except you because everybody will use the instruction code of a famous organization.
The instruction code does not have any meaning itself. The meaning of instruction code is stipulated by an organization or yourself. Then, that meaning must be materialized by many gates and the way they connect by wires.
Different types of computers will have different instruction code set, and we will not need to learn them in this post. But instruction code will be similar in the way that makes the computer work. In next posts, we will learn some simple instruction code that has simple wiring in the control unit that makes computers work.
Because our instruction code has eight bits or one byte, so we can have 256 different instruction codes. In reality, all these instruction codes will belong to one in nine types. From here, we can learn them more easily by finding out nine types of instruction code in turn. Remember that we are learning instruction codes to understand the way that instructions in computers work. Real computers will have more complex structure, but overview, it works in the same way.
In the previous post about the way that loading instruction codes to the CPU, you can see that the instructions can be loaded from the RAM, from the register and to the register and can also to the RAM (in later posts). Sometimes, the instructions also go through the ALU for calculating the next instruction.
In next posts, we will learn about instruction codes of nine types that we mentioned before. We will learn the bits in byte of instruction codes and the way we use gates and wire those gates together in the control unit. From that, we can understand the functions of instructions in computers. Hope you like this post. Thanks for reading and see you later !!!
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