NCERT Class 11 Informatics Practices Informatics Practices: Chapter 1 — Computer System
This chapter introduces the fundamental concept of a computer system, defining it as an electronic device that processes data. It explains that a computer system comprises a Central Processing Unit (CPU), memory, input/output devices, and storage devices working together. The chapter details the CPU's role as the 'brain' of the computer, consisting of the Arithmetic Logic Unit (ALU) for calculations and the Control Unit (CU) for managing operations. It also covers various input devices like keyboards and mice, which convert external data into a digital format understandable by the computer. The evolution of computers and computer memory are also briefly touched upon. This foundational knowledge is crucial for understanding subsequent topics in Informatics Practices for CBSE Class 11.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Informatics Practices |
| Book | Informatics Practices |
| Chapter | Chapter 1 — Computer System |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 3 minutes |
| Word count | 489 |
Learning outcomes
- Define a computer system and its primary components.
- Explain the functions of the Central Processing Unit (CPU), ALU, and CU.
- Identify and describe various input devices.
- Understand the basic concept of data flow within a computer system.
Vocabulary
| Word | Meaning |
|---|---|
| Data | Raw facts and figures processed by a computer. |
| Input | Data or instructions entered into a computer. |
| Process | To perform operations on data. |
| Output | The result generated by a computer after processing. |
| Computer System | A computer combined with hardware and software. |
| CPU | Central Processing Unit, the brain of the computer. |
| ALU | Arithmetic Logic Unit, performs calculations and logical operations. |
| CU | Control Unit, manages and coordinates computer operations. |
| Registers | Small, fast memory locations within the CPU. |
| Input Devices | Hardware used to enter data into a computer. |
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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.
- 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 carries out the actual processing of data and is often called the 'brain' of the computer.
- Name two examples of input devices. Answer: Keyboard and mouse are examples of input devices.
Practice MCQs
Q1. Which component is often referred to as the 'brain' of the computer?
Explanation: The CPU (Central Processing Unit) is responsible for executing instructions and processing data, earning it the nickname 'brain' of the computer.
Q2. What does the ALU perform?
Explanation: The Arithmetic Logic Unit (ALU) is a part of the CPU that handles all mathematical calculations and logical comparisons.
Q3. Which of the following is an input device?
Explanation: A scanner is an input device used to convert physical documents or images into digital data that a computer can process.
Q4. What is the primary function of the Control Unit (CU)?
Explanation: The Control Unit (CU) directs the flow of data and instructions, ensuring that operations are executed in the correct sequence.
Q5. A computer system includes hardware and:
Explanation: A computer system is defined as a computer combined with additional hardware and software components that enable it to function.
Frequently asked questions
What is a computer system?
A computer system is an electronic device that accepts data, processes it, and generates results, comprising hardware and software components.
What are the main parts of a CPU?
The CPU consists of the Arithmetic Logic Unit (ALU) and the Control Unit (CU), along with registers for temporary storage.
What is the difference between ALU and CU?
The ALU performs calculations and logic operations, while the CU controls the sequence of operations and data flow.
Give examples of input devices.
Common input devices include keyboard, mouse, scanner, and touch screen.
What is the purpose of registers in a CPU?
Registers are small, fast memory locations within the CPU used to store data, instructions, or intermediate results during processing.
How does a computer system process data?
It accepts data via input devices, processes it using the CPU (ALU and CU), stores intermediate results in memory/registers, and provides the final output.
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Topics covered
NCERT Class 11 Informatics Practices — Informatics Practices — Chapter 1 — Computer System. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.