Class 11th CBSE

Chapter 1 :- Computer System

Q.1 Name the software required to make a computer functional. Write down its two primary services.
Answer :-
System software is necessary for a computer to function, and the Operating System (OS) is the most crucial component. Linux, macOS, Windows, and other operating systems are examples. The OS controls system resources and makes it possible for hardware to communicate with software programs.

The operating system provides two main services:

1. Resource Management: The CPU, memory (RAM), disk space, and input/output devices are among the resources that the operating system controls. It guarantees that these resources are distributed among active processes in an equitable and effective manner, preventing disputes and optimizing system performance.

2. Process Management: The OS is in charge of establishing, planning, and ending processes, or computer programs. In addition to handling synchronization, inter-process communication, and deadlock prevention, it controls multitasking, making sure that every process receives the required amount of CPU time.

Q.2 How does the computer understand a program written in high level language?
Answer :-
Programs built in high-level languages like Python, Java, or C++ are not directly understandable by computers. High-level languages abstract away the intricate hardware details and are made to be readable by humans. However, only machine-level instructions—which are unique to the computer’s architecture—can be carried out by a computer. Consequently, the software must be converted into a computer-understandable format. One or more of the following approaches are used to handle this translation process:

Compiler :- A compiler translates the entire high-level program into machine code (binary instructions) in one go, creating an executable file. This translation happens before the program is run.
Interpreter :- An interpreter translates high-level instructions into machine code line-by-line, executing them immediately rather than producing a separate executable file.

Q.3 Why is the execution time of the machine code less than that of source code?

Answer :-
Machine code executes quicker than source code because it is immediately performed by the CPU without the need for translation, avoiding the overhead of compiling or interpreting. Furthermore, machine code is performance-optimized, which shortens execution time.

Q.4 Difference Between RAM and ROM

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Feature	RAM	ROM
1.Purpose	Temporary storage for active data and programs	Permanent storage for essential instructions or data that doesn't change (e.g., firmware).
2.Volatility	Volatile – data is lost when the power is turned off.	Non-volatile – data is retained even when the power is off.
3.Read/Write	Can be read from and written to by the CPU.	Generally read-only, although some types of ROM (e.g., EEPROM) can be written to under certain conditions..
4.Speed	Very fast data access and processing.	Slower compared to RAM, but sufficient for storing firmware or boot instructions.
5.Usage	Used by the operating system, applications, and data being actively processed.	Used to store firmware, system boot instructions, and critical system data (e.g., BIOS, UEFI).
6. Data Changes	Data in RAM changes constantly as programs run and data is processed.	Data in ROM is typically static and does not change during normal operation (except in specific types of ROM).
7. Typess	DRAM, SRAM, DDR, etc.	PROM, EPROM, EEPROM, Flash ROM.

Q.5 What is the need for secondary memory?

Answer :-

The need for secondary memory arises because primary memory (RAM) is not sufficient for the long-term storage of large amounts of data, programs, and files. Secondary memory provides:

Permanent storage for files, programs, and system data.
Larger capacity for storing vast amounts of data.
Cost-effective solutions for extensive storage needs.
Data persistence even when the system is powered off.
A place for backing up important data and system files.
The ability to store operating systems and applications, ensuring the system can run.

Secondary memory is crucial to contemporary computing because without it, a computer’s storage capacity would be constrained and data would be lost if the power was switched off.

Q.6 How do different components of the computer communicate with each other?

Answer :-
The communication between different components of a computer is facilitated through a combination of buses, interfaces, and protocols. These mechanisms enable data transfer, coordination, and control between the central processing unit (CPU), memory, storage devices, input/output (I/O) devices, and other hardware components.

Data Bus: Carries the actual data being transferred between components. It allows the CPU to send and receive data from memory, storage, or I/O devices.
Address Bus: Carries the memory addresses specifying where data is to be read from or written to. For example, the CPU uses the address bus to access specific locations in RAM or secondary storage.
Control Bus: Carries control signals that regulate the operations of other buses and devices. These signals tell the components when to read or write data, when to perform an operation, and how to manage the transfer of data.

These buses are critical for ensuring proper data flow and synchronization within the system. They are often organized into parallel buses (multiple data lines running in parallel) or serial buses (a single data line).

Q.7 Draw the block diagram of a computer system. Briefly write about the functionality of each component.
Answer :-

Input Devices:
Examples: Keyboard, Mouse, Microphone, Scanner.
Function: Input devices allow users to provide data or commands to the computer. They convert human-readable data (like typing, pointing, or scanning) into digital signals that the computer can understand and process.

Central Processing Unit (CPU):
The CPU is the brain of the computer and performs all the main processing tasks. It is responsible for executing instructions from programs and managing the flow of data between other components.
Key Sub-components of the CPU:
Control Unit (CU):
The CU manages the fetch-decode-execute cycle. It controls the flow of instructions and data between the CPU and other parts of the system (like memory and I/O devices).
It coordinates the execution of instructions by issuing commands to the ALU and other parts of the system.
Arithmetic and Logic Unit (ALU):
The ALU performs mathematical calculations (addition, subtraction, multiplication, division) and logical operations (AND, OR, NOT) on data.
It processes the data that the CPU receives and is responsible for the computational tasks required by programs.
Memory (Primary Storage/RAM):
Random Access Memory (RAM) is temporary (volatile) memory used to store data that is currently being used or processed by the CPU.
When you run a program, the operating system and the active programs are loaded into RAM so that the CPU can access them quickly.
RAM is much faster than secondary storage but loses all data when the system is powered off.
Secondary Memory (Storage):
Examples: Hard Disk Drive (HDD), Solid-State Drive (SSD), Optical Drives (CD/DVD), USB Drives.
Function: Secondary memory provides permanent storage for data, files, programs, and the operating system. Unlike RAM, data stored here is retained even when the computer is powered off.
It has a much larger storage capacity than RAM but is slower to access.
Output Devices:
Examples: Monitor, Printer, Speakers.
Function: Output devices allow the computer to display or present the processed information to the user in a human-readable format. For example, a monitor displays the results of a computation, while a printer produces a physical copy.