NCERT Solution Class 11 Computer Science Chapter 1
Class 11 Computer Science Chapter 1
SUMMARY :
A computing device, also referred as computer, processes the input data as per given instructions
to generate desired output.
Computer system has four physical components viz. (i) CPU, (ii) Primary Memory, (iii) Input Device
and (iv) Output Devices. They are referred to as hardware of computer.
Computer system has two types of primary memories viz. (i) RAM, the volatile memory and
(ii) ROM, the non-volatile memory.
System bus is used to transfer data, addresses and control signals between components of the
computer system.
A microprocessor is a small-sized electronic component inside a computer that performs basic
arithmetic and logical operations on data.
Microcontroller is a small computing device which has a CPU, a fixed amount of RAM, ROM and other
peripherals embedded on a single chip.
Software is a set of instructions written to achieve the desired tasks and are mainly categorised
as system software, programming tools and application software.
Hardware of a computer cannot function on its own. It needs software to be operational or functional.
Operating system is an interface between the user and the computer and supervises the working of
computer system, i.e., it monitors and controls the hardware and software of the computer system. Class 11 Computer Science Chapter 1
Class 11 Computer Science Chapter 1
Q1. Name the software required to make a computer functional. Write down its two primary services.
Ans. Humans are able to write programs in high-level language while computers can understand only machine language. so with the help of language translators (Compiler or Interpreter) programs written in HLL can be converted into machine language which is understood by computer.
Class 11 Computer Science Chapter 1
Q3. Why is the execution time of the machine code less than that of source code?
Ans. The program code written in assembly or high-level language is called source code. This source code is converted into machine understandable form called machine (object) code, So the execution time of machine code is less than that of source code.
Q4. What is the need of RAM? How does it differ from ROM?
Ans. RAM is used to store data temporarily while the computer is working. Whenever the computer is started or a software application is launched, the required program and data are loaded into RAM for processing.
Ans. Different components of the computer communicate with each other through Bus. For example, bus is used for data transfer between a USB port and hard disk or between a hard disk and main memory. Bus is of three types.
Data Bus
Address Bus
Control Bus
Q7. Draw the block diagram of a computer system. Briefly write about the functionality of each component.
Ans. A computer system primarily comprises a Central Processing Unit (CPU), memory, input/output devices and storage devices.
Class 11 Computer Science Chapter 1
1. CPU : The CPU has two main components — Arithmetic Logic Unit (ALU) and Control Unit (CU). ALU performs all the arithmetic and logical operations. The control unit controls the sequence in which computer programs and instructions are executed.
2. Input Device : The devices through which data/signals are sent to a computer are termed as input devices. for example : keyboard, mouse, scanner etc.
3. Output Devices : The device that receives data from a computer system for display is called output device. It converts digital information into human understandable form. For example, monitor, projector, headphone, speaker, printer, etc.
4. Storage Devices : A computer system needs memory to store the data and instructions for processing. Those devices which stores data for processing are called storage devices like Hard Disk, SSD etc
Class 11 Computer Science Chapter 1
Q8. What is the primary role of system bus? Why is data bus is bidirectional while address bus is unidirectional?
Ans. The System bus or bus provides a communication path between the major components of the Computer system.
Data bus is bidirectional as the CPU may require to read data from main memory or write data to main memory, while Address bus is unidirectional because the CPU is addressing a specific memory location either for reading or writing.
Q9. Differentiate between proprietary software and freeware software. Name two software for each type.
Q10. Write the main difference between microcontroller Notes and microprocessor. Why do smart home appliances have a microcontroller instead of microprocessor embedded in them?
Ans. The microcontroller is a small computing device which has a CPU, a fixed amount of RAM, ROM and other peripherals all embedded on a single chip as compared to microprocessor that has only a CPU on the chip.
Smart home appliances have a microcontroller because of it’s small size, it can be embedded in another device or system to perform a specific functionality. For example, the microcontroller in a fully automatic washing machine is used to control the washing cycle without any human intervention.
Class 11 Computer Science Chapter 1
Q11. Mention the different types of data that you deal with while browsing the Internet.
Ans. Different types of data that you deal with while browsing the Internet are:
1. Structured Data : Data which follows a strict record structure and is easy to comprehend is called structured data.
2. Unstructured Data : Data which are not organised in a pre-defined record format is called unstructured data.
3. Semi-structured Data : Data which have no well-defined structure but maintains internal tags or markings to separate data elements are called semi-structured data.
Q12. Categorise the following data as structured, semi structured and unstructured:
4. Patient records in a hospital : Structured Data
Class 11 Computer Science Chapter 1
Q13. 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
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