NCERT Class 11 Computer Science Computer Science: Chapter 1 — Computer System
This chapter introduces the fundamental concepts of a computer system, defining it as an electronic device that processes data. It outlines the primary components: Central Processing Unit (CPU), memory, input/output devices, and storage devices, explaining their collective function. The chapter details the CPU's role as the 'brain,' comprising the Arithmetic Logic Unit (ALU) for calculations and the Control Unit (CU) for managing operations. It also describes various input devices like keyboards and mice, and output devices such as monitors and printers, emphasizing their function in data conversion and presentation. The distinction between temporary primary memory (RAM) and permanent secondary storage is also highlighted. This foundational knowledge is crucial for understanding computer operations within the CBSE curriculum.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Computer Science |
| Book | Computer Science |
| Chapter | Chapter 1 — Computer System |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 624 |
Learning outcomes
- Define a computer system and its primary components.
- Explain the functions of the Central Processing Unit (CPU), including ALU and CU.
- Identify and describe various input and output devices.
- Differentiate between primary and secondary memory.
- Understand the flow of data and signals within a computer system.
Vocabulary
| Word | Meaning |
|---|---|
| Computer System | A computer along with additional hardware and software functioning together. |
| CPU | Central Processing Unit; the electronic circuitry that carries out processing, often called the brain of the computer. |
| ALU | Arithmetic Logic Unit; performs arithmetic and logic operations. |
| CU | Control Unit; controls instruction execution, interprets instructions, and guides data flow. |
| Registers | Local memory within the CPU for storing data, instructions, or intermediate results. |
| Input Devices | Devices that send control signals to a computer and convert input data into digital form. |
| Output Devices | Devices that receive data from a computer for display or physical production, converting digital information into a human-understandable form. |
| Primary Memory | Main memory (RAM) where data from input devices is temporarily stored. |
| Secondary Memory | Additional storage locations for permanent storage of data and instructions. |
| Microchips | Small pieces of semiconductor material containing integrated circuits (ICs). |
| Integrated Circuits (IC) | Electronic circuits fabricated on a small piece of semiconductor material. |
| Semiconductor Materials | Materials used in microchips and ICs, like silicon. |
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Practice questions
- What is a computer system? Answer: A computer system is a computer along with additional hardware and software that work together as a single unit.
- What are the main components of a computer system? Answer: The main components are the Central Processing Unit (CPU), memory, input/output devices, and storage devices.
- What is the role of the CPU? Answer: The CPU is responsible for carrying out the actual processing of data and instructions; it is often called the brain of the computer.
- Name two examples of input devices. Answer: Two examples are keyboard and mouse.
- Name two examples of output devices. Answer: Two examples are monitor and printer.
- What is the difference between primary and secondary memory? Answer: Primary memory (RAM) is temporary storage for active data and instructions, while secondary memory is for permanent storage.
Frequently asked questions
What is the primary function of a computer?
A computer is an electronic device that accepts data (input), processes it, and generates a result (output).
What are the main hardware components of a computer system?
The main hardware components are the CPU, memory, input devices, output devices, and storage devices.
What does CPU stand for and what is its function?
CPU stands for Central Processing Unit. It is the electronic circuitry that performs processing and is often called the brain of the computer.
What are the two main parts of the CPU?
The two main parts of the CPU are the Arithmetic Logic Unit (ALU) and the Control Unit (CU).
Give examples of input devices.
Examples of input devices include keyboard, mouse, scanner, and touch screen.
Give examples of output devices.
Examples of output devices include monitor, speaker, printer, and projector.
What is the difference between primary and secondary storage?
Primary memory (like RAM) is volatile and used for temporary storage during processing, while secondary storage (like hard drives) is non-volatile and used for permanent storage.
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NCERT Class 11 Computer Science — Computer Science — Chapter 1 — Computer System. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.