Computer Architecture — TechInterviewNotes

Computer architecture is the conceptual design and operational structure of a digital system.

It defines how hardware components interact to execute programs, spanning the instruction set architecture (ISA), CPU microarchitecture, memory, and I/O systems.To better understand how these foundational elements work, here is a breakdown of the core components and design principles:Core ComponentsCentral Processing Unit (CPU): The primary brain of the system, comprising the Arithmetic Logic Unit (ALU) for math and logic, and the Control Unit (CU) to dictate how data moves through the processor.Memory Hierarchy: The organization of storage, from fast, localized CPU registers and Cache to Main Memory (RAM) and external storage.Buses: The communication pathways that transfer data and control signals between the CPU, memory, and peripheral devices.Fundamental ParadigmsVon Neumann Architecture: Features a shared memory and pathways for both data and instructions. Because instructions must be read sequentially, this causes the "Von Neumann bottleneck".Harvard Architecture: Separates physical memory storage and pathways for instructions and data, allowing both to be accessed simultaneously.Instruction Set Architectures (ISA)The ISA serves as the bridge between software and hardware. It dictates the machine-language instructions a processor can execute. The two main philosophies include:RISC (Reduced Instruction Set Computer): Uses simpler instructions that execute in one clock cycle, optimizing for speed and power efficiency.CISC (Complex Instruction Set Computer): Uses complex instructions that can execute multiple low-level operations, reducing the number of total lines of code required.