Computer Architecture Overview

What is Computer Architecture

Computer Architecture studies the organization of computer systems — how CPUs execute instructions, how memory stores and retrieves data, and how various components work together. The core question: how does a computer run the programs you write?

Why Learn Computer Architecture

Understand why programs are fast or slow. Arrays are much faster than linked lists for the same algorithm — the reason is cache locality. With architecture knowledge, you can make informed optimization decisions.

Understand "abstraction leaks." Integer overflow, floating-point precision, concurrency races — the root causes are at the hardware level.

Foundation for embedded and systems programming. Essential for embedded development, device drivers, compilers, and performance optimization.

Key topic for exams and interviews. Instruction pipelines, cache principles, and bus arbitration are core exam and interview topics.

Core Knowledge Areas

Data Representation

• Binary and hexadecimal
• Integer representation: sign-magnitude, one's complement, two's complement
• Floating-point: IEEE 754
• Character encoding: ASCII, UTF-8

Instruction Set Architecture

• ISA: CISC vs RISC
• Instruction types: arithmetic, logical, control flow, memory access
• Assembly language: x86 or RISC-V

CPU Design

• Datapath: ALU, registers, buses
• Control unit: instructions to control signals
• Pipelining: fetch, decode, execute, memory access, write-back
• Pipeline hazards: data, control, structural

Memory Hierarchy

• Cache: L1/L2/L3, mapping policies, replacement strategies
• Main memory (DRAM): organization, bandwidth, latency
• Virtual memory: address translation, TLB, page replacement
• Memory locality: temporal and spatial

Buses and I/O

• Bus types: data, address, control
• I/O methods: programmed I/O, interrupts, DMA

Parallel Processing

• ILP: superscalar, out-of-order execution
• Data-Level Parallelism: SIMD, GPU
• Thread-Level Parallelism: multi-core, shared memory

How to Learn

Start with C and assembly. Write simple C programs and use gcc -S to see generated assembly.

Use simulation tools. Use Ripes or Venus to simulate RISC-V processor execution.

Draw datapath diagrams. Draw data flow between components during instruction execution.

Resources in This Module