| Type | Size / weight | Who uses it | Examples & speed |
|---|---|---|---|
| Supercomputer | Thousands of racks; a basketball court; 100+ tonnes; 20–30 MW (a small city) | Weather, nuclear, drug discovery, AI training | El Capitan (USA, 1.74 exaFLOPS, 2024), Frontier (1.35 EF), Fugaku (Japan), India: AIRAWAT (13 PF), PARAM Siddhi-AI, PARAM Rudra |
| Mainframe | Fridge-sized frame, 1–2 tonnes | Banks, railways (IRCTC), airlines, insurance — millions of transactions | IBM z16: 200 cores, 40 TB RAM; 99.99999% uptime |
| Minicomputer / mid-range server | Cupboard size | Universities, factories (1960s–80s) | PDP-11, VAX; today: IBM Power servers |
| Server | Rack unit (1U = 4.4 cm) to tower; 10–30 kg | Websites, cloud, databases | Dell PowerEdge; AMD EPYC 192 cores |
| Workstation | Large desktop; 15–25 kg | 3D animation, CAD, video editing, science | HP Z8, Mac Pro |
| Desktop PC (microcomputer) | Tower 5–15 kg; all-in-one | Home, office, gaming | Core i9 / Ryzen 9; 32 GB RAM |
| Laptop / notebook | 1–2.5 kg; 13–17 inch | Students, professionals | MacBook Air M4 (1.24 kg), ThinkPad, gaming laptops 2.5 kg |
| Netbook / Chromebook / Ultrabook | 0.9–1.3 kg | Web-centric, schools | Chromebook (ChromeOS) |
| 2-in-1 / tablet | 300–700 g | Reading, drawing, media | iPad Pro M4 (5.1 mm thin), Surface Pro |
| Smartphone | 150–240 g; 6–7 inch | 5 billion+ people | Snapdragon 8 Elite / Apple A18 — more powerful than a 2010 laptop |
| Wearable | 20–60 g | Health, notifications | Apple Watch, Fitbit, smart glasses |
| Single-board computer | 45 g (credit-card size) | Education, IoT, robotics | Raspberry Pi 5, Arduino (microcontroller) |
| Embedded computer | A few grams; inside other machines | Cars (100+ chips each), washing machines, ATMs, pacemakers, missiles | Microcontrollers (ARM Cortex-M, ESP32) |
| Quantum computer | Fridge-sized dilution refrigerator at 0.015 K (colder than space) | Research labs | Google Willow (105 qubits), IBM Condor (1,121 qubits) |
By data type
Analog
Works with continuous signals (voltage, temperature). Speedometer, thermometer, old slide rule, Antikythera.
Digital
Works with discrete 0/1 values. Every PC, phone, calculator.
Hybrid
Analog input + digital processing. ICU monitors, petrol pumps, ECG machines.
By purpose
- IGeneral-purpose — can run any program (PC, phone).
- IISpecial-purpose — built for one job (ATM, traffic light controller, washing machine, missile guidance).
- IIIServer vs Client — a server provides a service (web, mail, file); a client (your browser) requests it.
// Keep exploring
All chapters →