Hardware Fundamentals
Know what each piece does, and know its acronym.
| Component | What it does |
|---|---|
| CPU (Central Processing Unit) | The processor. Executes instructions. Measured in GHz and core count. |
| GPU (Graphics Processing Unit) | Renders graphics; also used for parallel math (AI, crypto). |
| RAM (Random Access Memory) | Volatile working memory. Erased when power is cut. |
| ROM (Read-Only Memory) | Non-volatile firmware storage. |
| HDD (Hard Disk Drive) | Spinning magnetic storage. Cheap, slow, mechanical. |
| SSD (Solid State Drive) | Flash storage. Much faster than HDD, no moving parts. |
| NVMe | High-speed SSD that connects to the PCIe bus, not SATA. |
| Motherboard | Main circuit board hosting CPU, RAM, and expansion slots. |
| PSU (Power Supply Unit) | Converts wall AC to low-voltage DC. |
| NIC (Network Interface Card) | Connects to a network (wired or wireless). |
| BIOS / UEFI | Firmware that runs at power-on and starts the OS. UEFI is modern. |
| Cache | Very fast CPU-local memory (L1/L2/L3). |
Volatile vs. non-volatile. Volatile memory (RAM, cache) loses contents on power loss. Non-volatile (SSD, HDD, ROM, USB flash) keeps them.
Memory hierarchy (fastest/smallest → slowest/largest): registers → cache → RAM → SSD → HDD → network/cloud.
Common ports and connectors: - USB-A / USB-C — general-purpose peripherals. USB-C is reversible. - HDMI / DisplayPort — digital video + audio. - Ethernet (RJ-45) — wired networking. - 3.5 mm — analog audio. - SATA — connects HDDs/SSDs to the motherboard.
Input vs. output devices. Keyboard, mouse, scanner, microphone = input. Monitor, speakers, printer = output. Touchscreen and multifunction printer = both.
RAID (Redundant Array of Independent Disks) — combines multiple drives. - RAID 0 — striping. Two drives appear as one larger, faster drive. No redundancy — losing either drive loses everything. - RAID 1 — mirroring. Two drives hold identical copies. Survives one drive failure. - RAID 5 — striping with parity across three or more drives. Survives one drive failure. - RAID 10 — mirror of stripes. Speed + redundancy. Needs four drives.