CPU Architecture Explained

#computerscience #cpu #processor
This video discusses the building blocks of a simple CPU, how they work individually, and how they cooperate to execute a set of instructions, which ultimatelly make any computer software run.

SUMMARY
To understand how CPU's work at the most fundamental level, we need to be familiar with it's most basic components, these are:
• The Arithmetic Logic Unit (ALU): the processor’s computational engine, responsible for executing arithmetic, logical, comparison, and shift operations.
• The Registers: a set of small, high-speed memory units, which are mainly found in the Register File, the Vector register block, and the Control Unit. Registers are used for temporarily holding data and instructions that are being actively used by other components, and are generally grouped into three types: General-Purpose, Special-Purpose, and Vector Registers.
• The Load/Store Unit: manages data transfers between the processor’s register file and external memory.
• Control Unit: fetches instructions from memory, decodes, and executes them, while managing all the other components.

Aside from these components, the processor also contains several subsystems that manage memory and data, maintain security, and improve system performance (the Memory Management Unit, Caches, and Memory Controller).

These components work together to execute a program through a continuous process called the Instruction Cycle. A classic instruction cycle includes 5 main stages:
• Fetch: Bringing the next instruction from memory into the processor's registers.
• Decode: Break the instruction down to its most basic components and generate signals for other components to prepare them for the execution of this specific instruction.
• Execute: The instruction is executed by the approproate component(s).
• Memory: Data is loaded from or stored into memory.
• Write-Back: The result of the instruction is stored.