Central Processing Unit (CPU) — the brain
| CPU part | Job | Hindi |
|---|---|---|
| Control Unit (CU) | Fetches instructions from memory, decodes them, and sends control signals to every other part — the traffic policeman | नियंत्रण इकाई |
| Arithmetic Logic Unit (ALU) | Does all maths (+ − × ÷) and logic (AND, OR, NOT, compare) | अंकगणितीय तर्क इकाई |
| Registers | Tiny ultra-fast storage inside the CPU: Program Counter (PC), Instruction Register (IR), Accumulator (AC), Memory Address Register (MAR), Memory Data Register (MDR) | रजिस्टर |
| Cache (L1 / L2 / L3) | Small very fast SRAM that keeps frequently used data next to the cores; L1 ≈ 32–64 KB per core, L3 up to 96 MB+ on AMD X3D chips | कैश स्मृति |
| Cores & threads | Each core is a complete CPU; modern chips have 4–24 cores (desktop) or 192 cores (server AMD EPYC). Hyper-threading lets one core run 2 threads | कोर |
| Clock | Crystal oscillator ticks billions of times per second (3–6 GHz) and synchronises every step | घड़ी |
| FPU / SIMD / NPU | Floating-point unit for decimals; SIMD (AVX, NEON) for vectors; NPU for AI (40+ TOPS in 2024 laptops) | — |
Machine cycle: FETCH the instruction (PC → MAR → memory → MDR → IR) → DECODE it in the CU → EXECUTE in the ALU → STORE the result (write-back). Then PC = PC + 1. A 4 GHz CPU repeats this 4 billion times each second, and pipelining lets it work on several instructions at once.
Memory hierarchy (fast & small → slow & big)
| Level | Type | Typical size | Speed (access) | Volatile? | Hindi |
|---|---|---|---|---|---|
| Registers | Inside CPU | a few hundred bytes | < 1 ns | Yes | रजिस्टर |
| Cache L1/L2/L3 | SRAM | KB → tens of MB | 1–10 ns | Yes | कैश |
| RAM (main memory) | DRAM — DDR4 / DDR5 / LPDDR5X | 8–64 GB | 50–100 ns | Yes — wiped when power goes | मुख्य स्मृति / यादृच्छिक अभिगम स्मृति |
| ROM / BIOS / UEFI | Flash (EEPROM) | 16–32 MB | ~100 ns | No | केवल पठनीय स्मृति |
| SSD | NAND flash (SATA ≈ 550 MB/s, NVMe PCIe 4/5 ≈ 7–14 GB/s) | 256 GB – 8 TB | ~0.05 ms | No | ठोस अवस्था ड्राइव |
| HDD | Magnetic spinning platters (5,400/7,200 rpm, ≈ 150–250 MB/s) | 1–24 TB | ~5–10 ms | No | हार्ड डिस्क |
| Optical | CD 700 MB · DVD 4.7 GB · Blu-ray 25–128 GB | — | slow | No | प्रकाशीय डिस्क |
| Tape (LTO-9) | Magnetic tape for archives | 18 TB per cartridge | minutes to seek | No | चुंबकीय टेप |
| Cloud | Someone else's data centre over the internet | unlimited | depends on network | No | क्लाउड |
- ITypes of RAM: SRAM (fast, used in cache), DRAM (needs refresh; used as main memory), SDRAM, DDR1→DDR5, LPDDR (phones), GDDR6/GDDR7 (graphics cards), HBM (AI chips).
- IITypes of ROM: PROM (program once), EPROM (erase with UV light), EEPROM/Flash (erase electrically — pen drives, SSDs, BIOS chip).
- IIIVirtual memory: when RAM is full, the OS uses part of the SSD/HDD as 'page file' or 'swap' — slower but prevents crashes.
Motherboard components
| Component | What it does |
|---|---|
| CPU socket (LGA 1851 Intel, AM5 AMD) | Holds the processor; has 1,000–2,000 contact pins |
| Chipset (Intel Z890 / AMD X870) | Traffic controller between CPU, RAM, storage and ports (older boards had a Northbridge + Southbridge) |
| RAM slots (DIMM) | 2–4 slots; dual-channel doubles bandwidth |
| PCIe slots (x16, x4, x1) | Graphics card, capture card, Wi-Fi card; PCIe 5.0 x16 = 64 GB/s each direction |
| M.2 slots | NVMe SSDs and Wi-Fi modules — 22 mm wide, 80 mm long (2280) |
| SATA ports | 2.5-inch SSDs and 3.5-inch HDDs at 6 Gb/s |
| BIOS / UEFI chip | Firmware that tests hardware (POST) and starts the OS; settings stored in CMOS |
| CMOS battery (CR2032) | Keeps clock & BIOS settings when the PC is off — if the date resets, replace it |
| VRM (voltage regulator module) | Converts 12 V to the CPU's ~1.2 V with heavy current; has its own heatsinks |
| Power connectors (24-pin ATX, 8-pin EPS) | Bring power from the PSU |
| Front-panel header, fan headers, USB headers | Power button, LEDs, case fans, case USB ports |
| Rear I/O panel | USB-A/USB-C/Thunderbolt, HDMI/DisplayPort, Ethernet, audio jacks, PS/2, antenna |
| Buses | Address bus (where), Data bus (what), Control bus (how) — the 'roads' on the board |
Input devices (data goes INTO the computer)
| Device | Hindi | Notes |
|---|---|---|
| Keyboard | कुंजीपटल | QWERTY layout (1873 typewriter); 104 keys standard; types: membrane, mechanical, chiclet, virtual |
| Mouse | माउस / चूहा | Mechanical ball (1968) → optical (1999) → laser; DPI = sensitivity; invented by Engelbart |
| Touchpad / Trackpoint | स्पर्श पट्ट | Laptops |
| Touchscreen | स्पर्श पटल | Resistive (pressure) vs capacitive (finger charge) — phones use capacitive |
| Scanner | क्रमवीक्षक | Flatbed, handheld, sheet-fed; OCR converts scanned text to editable text |
| Barcode / QR reader | बारकोड पाठक | Shops, UPI payments |
| Microphone | ध्वनिग्राहक | Voice input; speech-to-text |
| Webcam / camera | कैमरा | Video calls, face unlock |
| Joystick / gamepad | जॉयस्टिक | Gaming, drones |
| Light pen & graphics tablet (stylus) | प्रकाश लेखनी | Drawing, signatures |
| OMR / OCR / MICR | — | OMR reads bubbles on exam sheets; OCR reads printed text; MICR reads magnetic ink on cheques |
| Biometric sensors | बायोमेट्रिक | Fingerprint, iris, face (Aadhaar uses all three) |
| Sensors (IoT) | संवेदक | Temperature, GPS, accelerometer, gyroscope in every phone |
Output devices (information comes OUT)
| Device | Hindi | Notes |
|---|---|---|
| Monitor | मॉनिटर / प्रदर्शक | CRT (heavy glass tube, till 2005) → LCD → LED-backlit → OLED → mini-LED; resolution 1080p / 1440p / 4K / 8K; refresh 60–540 Hz |
| Printer | मुद्रक | Impact: dot-matrix (noisy, carbon copies). Non-impact: inkjet (home), laser (office, toner), thermal (bills/ATM), 3D printer (objects) |
| Speakers / headphones | ध्वनि विस्तारक | Sound output |
| Projector | प्रक्षेपक | Classrooms, cinema |
| Plotter | आलेखित्र | Large engineering drawings; uses pens |
| Braille display / embosser | ब्रेल | For visually impaired users |
| Haptic / vibration motor | — | Phones, game controllers |
| Both input & output | — | Touchscreen, modem, network card, headset, VR headset, USB drive |
Other hardware
| Part | Job | Typical specs |
|---|---|---|
| GPU / graphics card | Thousands of small cores draw pixels and run AI maths in parallel | Nvidia RTX 5090: 21,760 cores, 32 GB GDDR7, 575 W; integrated GPUs share RAM |
| Power Supply Unit (PSU / SMPS) | Converts 230 V AC to 12 V / 5 V / 3.3 V DC | 450–1,000 W; 80 Plus Bronze/Gold/Platinum efficiency ratings |
| Cooling | Removes heat — a CPU can reach 100 °C | Heatsink + fan, liquid AIO cooler, thermal paste, case fans |
| Cabinet / chassis | Holds everything | Full tower, mid tower, mini-ITX, all-in-one |
| Network card (NIC) / Wi-Fi / Bluetooth | Connects to other computers | 2.5 Gb/s Ethernet, Wi-Fi 7 (46 Gb/s theoretical), Bluetooth 5.4 |
| Sound card | Converts digital audio ↔ analog | Usually built into the motherboard |
| UPS | Battery backup during power cuts | 600 VA – 2 kVA for homes |
| Expansion cards | Capture cards, RAID, extra USB | PCIe |
Ports & connectors
| Port | Used for | Speed / note |
|---|---|---|
| USB-A 2.0 / 3.x | Keyboard, mouse, pen drive | 480 Mb/s / 5–20 Gb/s |
| USB-C / Thunderbolt 4–5 | Charging (up to 240 W), display, data — one port for everything | 40 / 80 Gb/s |
| HDMI 2.1 | TV & monitor video + audio | 48 Gb/s; 4K@120 Hz |
| DisplayPort 2.1 | Monitors | 80 Gb/s; 8K |
| VGA / DVI | Old monitors (analog / digital) | Legacy |
| RJ-45 Ethernet | Wired internet | 1–10 Gb/s |
| 3.5 mm audio jack | Headphones, mic | Analog |
| SD / microSD card slot | Cameras, phones | UHS-II up to 312 MB/s |
| PS/2 | Old keyboard/mouse (purple/green) | Legacy |
| Lightning | Older iPhones (2012–2023) | Replaced by USB-C in 2023 |
// Keep exploring
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