NoticeThe following posts are based on concepts I studied from "Core Notes on Computer Structure and Operating Systems "by Ji-young Seo, published by Gilbut. Each post represents my personal understanding and interpretation of the material. Some explanations might include inaccuracies, if you notice any, please let me know so that I can review and correct them promptly.
In modern society, our lives are inseparable from computers. Even the smartphone we use to watch YouTube before going to bed is, in essence, a small computer. Likewise, in most workplaces, performing daily tasks almost always requires the use of a computer (though there may be some exceptions).
If you’re not working in a computer-related field, knowing how to use a computer might be sufficient. However, for developers or computer science majors, the story is different. Computer Structure is the fundamental study that helps us understand how the tool we use computers actually work and operate.
In other words, to become a skilled programmer, it’s not enough to simply know how to write code. One must also understand how that code is executed on hardware in practice. From this perspective, Computer Structure serves as the root of programming and represents one of the most essential foundations every developer should learn.
Components of a Computer
A computer can be broadly divided into hardware and software.
Software refers to all the programs that run on a computer, such as operating systems and application programs, while hardware refers to the physical components of a computer, such as the monitor, keyboard, mouse, CPU, and memory.
When broken down in more detail, computer hardware consists of the Central Processing Unit (CPU), memory, and input/output devices.
Of course, an actual computer also includes components such as a power supply and cooling system, which are essential for maintaining system stability.
However, since our focus here is on understanding how a computer operates, we will set aside these auxiliary components for now and concentrate on the core parts.
The Basic Structure of a Computer
As mentioned earlier, a computer is largely composed of software and hardware.
The instructions entered through software are transmitted via a “system bus” within the hardware.
You can think of the system bus as a “road,” and the cars traveling on that road represent the instructions and data.
In other words, the system bus serves as the pathway that allows instructions and data to move between hardware components such as the CPU, memory, and input/output devices.
CPU
The CPU is the “brain” of the computer. Just as a person performs all thinking and decision-making with the brain, most of a computer’s processing and control are carried out by the CPU.
The CPU is mainly composed of an Arithmetic and Logic Unit (ALU) and a Control Unit (CU), each of which has its own distinct characteristics and functions.
The Arithmetic and Logic Unit (ALU) is responsible for performing mathematical calculations and logical operations within the computer.
It handles basic arithmetic (addition, subtraction, multiplication, division) as well as logical operations such as AND, OR, and NOT.
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AND – Returns true only when both conditions are true.
Example : (A = True) AND (B = True) → Result : True
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OR – Returns true when at least one of the conditions is true.
Example : (A = True) OR (B = False) → Result : True
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NOT – Reverses the truth value of a condition.
Example : NOT(True) → False, NOT(False) → True