Computer System & Its Components
A computer in your pocket
When you scan a QR code to pay at a tea stall, your phone's camera takes the picture (input), the processor reads the code and talks to the bank (processing), the screen shows "₹20 paid" (output) and the payment history is saved (storage). Your phone is doing exactly what every computer does — only it fits in your pocket.
What is a computer system?
A computer is a programmable electronic device that takes data as input, processes it under the control of instructions, produces information as output and can store both. A computer system includes the hardware, the software, the data and the people (users) who work together.
Block diagram
The block diagram shows the main units and how data flows among them. The CPU sits in the middle; all data goes into memory first and the CPU works on it from there.
Input and output devices
Input devices
- Keyboard, mouse, touchpad
- Microphone (voice search)
- Scanner, webcam, QR / barcode reader
- Biometric scanner (fingerprint attendance)
- Sensors: temperature, motion, GPS
Output devices
- Monitor / screen (soft copy)
- Printer and 3D printer (hard copy)
- Speaker, headphones
- Projector, smart board
- Braille display for blind users
Some devices do both: a touch screen, a headset with microphone and a modem are input as well as output devices.
The CPU
The Central Processing Unit is the "brain" of the computer. It is a single chip called a microprocessor (for example Intel Core i5, AMD Ryzen, Apple M3, Snapdragon in phones).
- ALU (Arithmetic Logic Unit): does calculations (+ − × ÷) and comparisons (>, <, =).
- CU (Control Unit): reads each instruction, understands it and tells the other parts what to do and when.
- Registers: tiny, very fast memory locations inside the CPU that hold the data being processed right now.
Kinds of computers
| Kind | Size and power | Used for |
|---|---|---|
| Supercomputer | Thousands of processors, fastest | Weather forecasting, space research (India's PARAM series) |
| Mainframe | Very large, many users at once | Banks, railway reservation, insurance |
| Server | Powerful, always on | Websites, email, cloud services |
| Personal computer / laptop | One user | Study, office work, coding, games |
| Tablet and smartphone | Handheld, battery powered | Calls, apps, photos, payments |
| Embedded computer | Tiny chip inside a machine | Washing machine, ATM, car, smart TV |
How computers evolved
Over time computers became smaller, faster, cheaper, more reliable and easier to use. The stored-program idea of John von Neumann — keeping instructions and data together in memory — is still the basis of computers today.
Summary & practice
- Computer: input → process → output, with storage.
- Computer system = hardware + software + data + users.
- CPU = ALU + CU + registers; it is a microprocessor chip.
- Kinds: supercomputer, mainframe, server, PC, mobile, embedded.
1) Write the input, process and output of a fitness band that counts your steps. 2) Which kind of computer does IRCTC use for ticket booking? 3) Name two devices that are both input and output.
Answers: 1) Input: motion sensor readings; Process: count steps and calculate distance and calories; Output: numbers on band/app. 2) Mainframe / servers. 3) Touch screen, headset with mic.
