This page contains the NCERT Computer Science class 11 chapter 1 Computer System. You can find the solutions for the chapter 1 of NCERT class 11 Computer Science Exercise. So is the case if you are looking for NCERT class 11 Computer Science related topic Computer System questions and answers for the Exercise
Exercise
1) Name the software required to make a computer functional. Write down its two primary services.
The software required is the Operating System (OS) (it is the most important system software).
Its two primary services/objectives are:
•
Provide services for building and running application programs (loads programs into memory, allocates CPU, decides execution order).
•
Provide an interface to the user so the user can interact with the computer (user interface takes commands/inputs).
2) How does the computer understand a program written in high level language?
A computer does not understand high level language directly. The CPU can execute only machine language, which is in binary (0s and 1s).
So, when we write a program in a high level language, it is first written as source code, and then it is converted into machine code (also called object code) using a language translator.
Flow:
Source Code (High Level Language) → Translator → Object Code / Machine Code → Execution
Language translators
1. Compiler
•
Converts the entire source code into object code in one go.
•
If there are errors, the compiler reports them after compiling.
•
Once compiled successfully, the program can be run (object code is used for execution).
2. Interpreter
•
Translates and executes line-by-line (one statement at a time).
•
It checks each line and shows errors immediately for that line.
•
It is generally needed each time the program is run because it translates while executing.
3. Assembler
•
Converts assembly language into machine language (object code).
✅ Conclusion: The computer understands a high level language program only after a translator converts the source code into machine (object) code, which the CPU can execute.
3) Why is the execution time of the machine code less than that of source code?
Because machine language uses 1s and 0s and is directly understood and executed by the computer, while high-level language is not directly understood and needs translation first.
4) What is the need of RAM? How does it differ from ROM?
Need of RAM: Programs and data are loaded into RAM for processing; it stores data temporarily while the computer is working.
Differences:
Basis
RAM
(Random Access Memory)
(Random Access Memory)
ROM
(Read Only Memory)
(Read Only Memory)
Type of memory
Primary memory used while working
Primary memory used for permanent instructions
Nature
Volatile
Non-volatile
When power is OFF
Data gets erased
Data is not erased
Purpose
Stores data/programs temporarily while the computer is working
Stores permanent content needed for starting the computer
Example mentioned
Working data / running program data
Boot loader (stored permanently)
5) What is the need for secondary memory?
Primary memory is limited and RAM is volatile, so we need secondary memory to permanently store data/instructions for future use. It is non-volatile and has larger storage capacity (like HDD, CD/DVD, memory card, etc.).
6) How do different components of the computer communicate with each other?
They communicate using bus (physical wires). The system bus includes:
•
Data bus (transfers data),
•
Address bus (transfers addresses between CPU and main memory),
•
Control bus (transfers control signals).
7) Draw the block diagram of a computer system. Briefly write about the functionality of each component.
Block diagram (text form):
Input Device → CPU (CU + ALU) ↔ Primary Memory → Output Device
Secondary Storage Devices ↔ Primary Memory
Functionality of each component
1) Input Devices
•
Used to enter data and instructions into the computer.
•
They send control signals and data to the computer.
•
They convert the input into digital form that the computer can understand.
Examples: keyboard, mouse, scanner, microphone, touchscreen.
2) CPU (Central Processing Unit)
•
The CPU is the brain of the computer.
•
It performs the actual processing and controls all operations.
•
It has two main parts:
(a)
Control Unit (CU)
•
Controls sequential instruction execution.
•
Interprets instructions and coordinates the working of all parts.
•
Guides the flow of data between memory, ALU, and input/output devices.
(b)
Arithmetic Logic Unit (ALU)
•
Performs arithmetic operations like +, −, ×, ÷.
•
Performs logical operations like comparison (>, <, =) and logic (AND, OR, NOT).
3) Primary Memory (Main Memory)
•
Stores data and instructions temporarily while the computer is working (mainly RAM).
•
Also contains ROM which stores permanent instructions used during starting/booting.
•
CPU can access it directly, so it is needed during program execution.
4) Secondary Storage Devices
•
Used for permanent storage (non-volatile).
•
Stores data/programs for future use.
•
Before processing, data/programs are brought from secondary storage into primary memory.
Examples: HDD/SSD, CD/DVD, pen drive, memory card.
5) Output Devices
•
Show the result after processing.
•
Convert digital output into human-understandable form.
Examples: monitor, printer, speaker, projector.
8) What is the primary role of system bus? Why is data bus bidirectional while address bus is unidirectional?
Primary role: System bus transfers data, addresses and control signals between components.
•
Data bus is bidirectional because CPU may read data from memory or write data to memory.
•
Address bus is unidirectional because CPU places the address of the memory location it wants to access.
9) Differentiate between proprietary software and freeware software. Name two software for each type.
•
Freeware: freely available for use, but source code may not be available (examples: Skype, Adobe Reader). More examples include Whatsapp/Google Chrome etc.
•
Proprietary software: must be purchased from the vendor who has copyright (examples: Microsoft Windows, Tally / Quickheal). More examples include Adoble Photoshop, MS Office, Oracle Database etc.
10) Difference between microcontroller and microprocessor. Why smart home appliances use microcontroller?
Main difference
Basis
Microprocessor
Microcontroller
What it mainly contains
Mainly CPU on a single chip
CPU + fixed RAM + ROM + peripherals (all embedded on a single chip)
Main use
Used for general-purpose processing (needs external components like memory, I/O, etc.)
Used for specific, dedicated tasks inside devices (works as a complete “small computer” on one chip)
Why smart home appliances use a microcontroller (instead of a microprocessor)
Smart home appliances (like washing machines, microwaves, remote controllers, etc.) perform specific fixed functions. A microcontroller is best for this because it already has CPU, RAM, ROM and peripherals embedded on a single chip, which:
•
reduces size
•
reduces cost
•
makes the device easier to embed and control efficiently for a particular job
So, appliances use a microcontroller because it is designed for embedded control and dedicated tasks, not heavy general-purpose computing.
11) Mention different types of data you deal with while browsing the Internet.
While browsing the Internet, we come across different types of data. In this chapter, data is mainly classified into these three categories:
1.
Structured data
•
Data arranged in a fixed format (rows/columns).
•
Example: tables showing marks, product lists, cricket score tables, forms saved in databases.
2.
Semi-structured data
•
Data that does not follow a strict table structure, but still has tags/markers to organise it.
•
Example: HTML web pages, emails, XML/JSON-like data.
3.
Unstructured data
•
Data that has no predefined structure.
•
Example: text paragraphs, pictures/images, audio/songs, videos, graphics, etc.
So, while browsing, we handle structured, semi-structured, and unstructured data (often all on the same website page).
12) Categorise the following data as structured, semi-structured and unstructured:
•
Newspaper
•
Cricket Match Score
•
HTML Page
•
Patient records in a hospital
Definitions:
•
Structured data: follows strict record structure / tabular format.
•
Unstructured data: not organised in predefined record format (audio/video, text documents, graphics, etc.).
•
Semi-structured data: no well-defined structure but uses internal tags/markings (examples include HTML page, email, CSV).
Now categorisation:
•
Newspaper → Unstructured (mix of text, photos, layout; not a strict tabular record).
•
Cricket Match Score → Structured (score is typically in a fixed record/table format).
•
HTML Page → Semi-structured (similar to the news paper, for example visit any news website).
•
Patient records in a hospital → Structured (generally stored in records/tables like databases).
13) Name the input or output device used to do the following:
a)
To output audio
b)
To enter textual data
c)
To make hard copy of a text file
d)
To display the data or information
e)
To enter audio-based command
f)
To build 3D models
g)
To assist a visually-impaired individual in entering data
a)
To output audio → Speaker / Headphone
b)
To enter textual data → Keyboard
c)
To make hard copy of a text file → Printer
d)
To display the data or information → Display monitor / Projector
e)
To enter audio-based command → Microphone / voice input (voice input mentioned in input devices).
f)
To build 3D models → 3D printer (builds physical replica of a digital 3D design).
g)
To assist a visually-impaired individual in entering data → Braille keyboard
14) Identify the category (system, application, programming tool) of the following software:
a)
Compiler
b)
Assembler
c)
Ubuntu
d)
Text editor
•
a) Compiler → Programming tool
•
b) Assembler → Programming tool
•
c) Ubuntu → System software (Operating system)
•
d) Text editor → Programming tool (used for writing/editing code)
Explore Yourself
(answers are student-specific)
These depend on your own computer/school lab, so here’s how to write them:
1. Ask your teacher to help you locate any two device drivers installed on your computer.
Answer (Explore Yourself – Sample Response):
With my teacher’s help, I located these two device drivers installed on my computer:
1.
Display/Graphics Driver (for the monitor/graphics card)
2.
Printer Driver (for the printer)
Note (keyword): A device driver is a type of system software that helps the operating system communicate with a hardware device.
(If you want alternatives: Sound/Audio driver, Network/Wi-Fi driver, Keyboard/Mouse driver are also common device drivers.)
2. Write any two system software and two application software installed on your computer.
Answer (Explore Yourself – Sample Response):
Two System Software (installed on my computer):
1.
Operating System – Microsoft Windows / Ubuntu
2.
Language Translator – Compiler / Interpreter (any one installed with a programming setup)
Two Application Software (installed on my computer):
1.
Web Browser – Google Chrome / Mozilla Firefox
2.
Word Processor – Microsoft Word / LibreOffice Writer
Keywords:
•
System software helps in running/controlling the computer system (example: Operating System, translators).
•
Application software is used to perform user tasks (example: browser, word processor).
3. Which microprocessor does your personal computer have? Which generation does it belong to?
Answer (Explore Yourself – Sample Response):
With my teacher’s help, I checked the System Information / Task Manager of my computer.
•
Microprocessor: (write the exact name shown on your PC)
Example: Intel® Core™ i5-1135G7
•
Generation: (based on the model number)
Example: 11th Generation (because i5-1135G7 starts with 11)
How to find it (quick method)
•
Windows: `Task Manager → Performance → CPU` (or `Settings → System → About`)
•
The CPU name will appear there.
How to identify the generation (keyword: generation)
•
For Intel Core i3/i5/i7/i9, look at the digits after the hyphen (-):
•
i5-8250U → 8th Gen (starts with 8)
•
i7-10510U → 10th Gen (starts with 10)
•
i5-12400 → 12th Gen (starts with 12)
4. What is the clock speed of your microprocessor?
Answer (Explore Yourself – Sample Response):
With my teacher’s help, I checked the System Information / Task Manager of my computer.
•
Clock speed of my microprocessor: _____ GHz
(Write the value shown on your computer. Example: 2.40 GHz / 3.10 GHz.)
How I found it (simple):
•
Windows: `Task Manager → Performance → CPU` → look for Speed (or `Settings → System → About` / `System Information`).
Keyword (meaning):
Clock speed is the speed at which a microprocessor executes instructions, usually measured in GHz (gigahertz).
5. Name any two devices in your school or home that have a microcontroller.
Answer (Explore Yourself – Sample Response):
Two devices in my home/school that have a microcontroller are:
1.
Washing machine
2.
Microwave oven
(These appliances perform specific fixed functions, so a microcontroller is embedded in them for control.)