พื้นฐานสถาปัตยกรรม x86

The x86 architecture powers most PCs — an Intel instruction-set family dating back to the 8086. Knowing it shows how software meets hardware.

The CPU is the brain of an x86 system: it executes instructions, does the math, and conducts data flow like an orchestra leader.

A CPU has key parts working together: the ALU for math and logic, the Control Unit to decode instructions, and fast on-chip registers.

x86 CPUs run in different modes that set how much memory and which features are available. The big three: Real, Protected, and Long Mode.

Real Mode is the CPU's boot state: 16-bit, capped at 1MB of memory, direct hardware access but no protection. This is where DOS lived.

Protected Mode is the 32-bit leap: up to 4GB of memory plus memory protection, multitasking, and virtual memory between programs.

Long Mode is the 64-bit world (x86-64 / AMD64) used by modern OSes. It blows past the 4GB limit with 64-bit registers and addressing.

An instruction set is every command a CPU understands. x86 is CISC, so single instructions can be powerful and do several steps at once.

Think of memory as one giant ordered array: each slot holds a byte and has a unique numeric address the CPU uses to read and write.

You explored x86: the CPU and its parts, the Real/Protected/Long modes, instruction sets, and byte-addressable memory. Next: your first program!