Summary of Computer Architecture and Internal Components

## Introduction Computer Hardware Fundamentals gives you the practical, conceptual building blocks to understand how everyday computers work. This guide focuses on core ideas you will use when troubleshooting, choosing upgrades, or studying computing systems. Concepts are broken into small sections with clear definitions, examples, and quick comparisons. > Definition: Hardware refers to the physical parts of a computer that process, store, and move data. ## 1. Volatile vs. Persistent Storage ### What they are - **Volatile storage (RAM):** Fast memory the CPU uses while programs run. It loses its contents when power is removed. - **Persistent storage (HDD, SSD):** Non-volatile devices that retain data when the computer is powered off. > Definition: RAM (Random Access Memory) is temporary working memory that holds data the CPU is actively using; it is cleared when power is lost. > Definition: SSD (Solid State Drive) and HDD (Hard Disk Drive) are persistent storage devices that keep data without power. ### Key differences (table) | Property | RAM | Persistent storage (SSD/HDD) | |---|---:|---| | Data retention when powered off | No | Yes | | Typical speed | Very fast | Fast (SSD) / slower (HDD) | | Use case | Active program data | Files, installed applications, OS | ### Practical example - You write a document in a text editor: the editor keeps unsaved changes in RAM. If power is lost before saving, those changes vanish. When you save the file, the editor writes it to persistent storage, where it remains after reboot. Fun fact: Modern SSDs use flash memory cells that retain charge to store bits even without power. ## 2. CPU, Cores, and Performance ### CPU basics - **CPU (Central Processing Unit):** Executes program instructions. More powerful CPUs complete tasks faster. - **Core:** An independent processing unit inside a CPU. A 4-core CPU can run multiple threads simultaneously. > Definition: Core is an independent execution unit within a CPU that can run tasks in parallel with other cores. ### When CPU matters - CPU-bound tasks: complex calculations, video encoding, and some games rely primarily on CPU speed. - Multi-threaded tasks benefit from more cores; single-threaded tasks rely on higher clock speed and IPC (instructions per clock). ### Practical example - An old CPU with modern fast storage may still struggle in tasks that need high instruction throughput. ## 3. How RAM Size Affects System Behavior - If RAM is sufficient, programs run smoothly and the OS keeps frequently used data in RAM. - If RAM fills up, the OS uses slower persistent storage (swap or pagefile), causing significant slowdowns. > Definition: Throttling is the automatic reduction of CPU or GPU clock speed to reduce heat and protect hardware. ### Practical example - Having many browser tabs and applications can exhaust RAM; the system will swap to disk and feel sluggish even if the CPU is relatively fast. ## 4. Storage Interfaces and Speeds ### Common interfaces and terms - **SATA:** Older, common interface for HDDs and some SSDs. Moderate speed. - **M.2 and NVMe:** Modern SSD form factor and protocol. NVMe over PCIe provides much higher throughput and lower latency. - **HDD:** Uses spinning platters; larger capacity but slower and mechanically vulnerable. > Definition: NVMe (Non-Volatile Memory Express) is a fast protocol for SSDs that reduces latency and increases throughput compared with SATA. ### Table: Typical performance comparison | Device | Typical latency | Typical throughput | |---|---:|---:| | HDD | High | 50-200 MB/s | | SATA SSD | Low | 200-600 MB/s | | NVMe M.2 SSD | Very low | 1000+ MB/s | ### Practical example - A heavy application stored on an HDD will load much slower than the same application on an NVMe SSD, even on the same CPU. Did you know that NVMe drives connect directly to PCIe lanes, which is why they can achieve much higher speeds than SATA drives? ## 5. Graphics and VRAM - **GPU (Graphics Processing Unit):** Sp