Loading...
Please wait while we prepare your content
Please wait while we prepare your content
Solutions for Computer Science, Class 11, CBSE
Assertion (A): Computer is an electronic device that accepts input, processes it and displays the output.
Reasoning (R): Computer is a combination of hardware and software. Every task given to it follows IPO cycle.
Both A and R are true and R is the correct explanation of A.
Explanation
A computer is an electronic device that accepts a set of instructions in the form of a program, executes it and displays the output to the user. Computer is a combination of hardware and software. Every task given to a computer follows an Input → Process → Output Cycle (IPO cycle).
Assertion (A): Primary memory is the main memory inside computer that holds data, programs and instructions that are currently in use.
Reasoning (R): Secondary memory is used for permanent storage of data for future use.
Both A and R are true but R is not the correct explanation of A.
Explanation
Primary memory, also known as main memory, is the memory inside a computer that holds data, programs, and instructions that are currently in use. Secondary memory, also known as auxiliary memory, is used for permanent storage of data for future use.
Assertion (A): Cache memory is placed between CPU and main memory (RAM).
Reasoning (R): Cache memory stores frequently used data and instructions so that they are immediately available to the CPU.
Both A and R are true and R is the correct explanation of A.
Explanation
Cache memory is placed between the CPU and the main memory (RAM) to store frequently used data and instructions. By doing so, it makes this data available to the CPU very quickly, sending it directly to the CPU instead of the main memory. This significantly reduces access time, thereby improving the overall performance of the computer.
Assertion (A): Registers are the components that provide internal storage to the CPU.
Reasoning (R): User has direct access to CPU registers.
A is true but R is false.
Explanation
Registers are high-speed temporary storage areas found in the CPU. Registers work as per the instructions given by the control unit (CU), storing instructions and data. However, users do not have direct access to CPU register.
Assertion (A): Operating system is the most important utility software.
Reasoning (R): Utility Software are essential for maintenance and configuration of the computer system.
A is false but R is true.
Explanation
An operating system is not considered utility software, it is classified as system software. Utility software consists of programs that assist the computer by performing certain tasks that help in the proper maintenance and configuration of the computer.
Assertion (A): Operating system acts as an interface between a user and computer hardware.
Reasoning (R): Operating system manages all the resources of a computer.
Both A and R are true and R is the correct explanation of A.
Explanation
An operating system (OS) is a program that acts as an interface between the user and hardware of the computer. The OS helps to manage resources of the computer and optimize its performance.
Assertion (A): Three types of translators used in computing system are assemblers, compilers and interpreters.
Reasoning (R): A translator is used to convert program written in high-level language to binary language.
Both A and R are true and R is not the correct explanation of A.
Explanation
The translators can be of three types: assembler, compiler and interpreter. A translator is used to translate the program written in high-level language into machine code.
All of these
Reason — Utilities are system software designed to help analyze, configure, optimize, or maintain a computer. Text editors, backup tools, and disk defragmenters all fall under this category.
CPU
Reason — The CPU, or Central Processing Unit, is referred to as the brain of the computer because it guides, directs, controls and governs all the processing that takes place inside the computer.
Barcode Reader
Reason — A barcode is a collection or a sequence of lines of different heights and widths that are printed on various types of products.
Biometric sensor
Reason — Biometric sensor uniquely identifies a person on the basis of physical or behavioral traits such as eyes, fingerprints, DNA, etc.
CU
Reason — The Control Unit (CU) directs and coordinates all activities within the CPU and determines the sequence in which instructions are executed, sending instruction sequences to other smaller units.
Hard disk
Reason — A hard disk is a type of non-volatile memory, meaning it retains data or information permanently even when the computer is turned off.
2831155.2
Reason — To convert gigabytes (GB) to kilobytes (KB), we use the following conversion factors:
1 GB = 1024 MB (megabytes)
1 MB = 1024 KB (kilobytes)
First, convert gigabytes to megabytes: 2.7 GB * 1024 = 2764.8 MB
Next, convert megabytes to kilobytes: 2,764.8 MB * 1024 = 2831155.2 KB
Therefore, 2.7 GB equals 2831155.2 kilobytes.
The Arithmetic Logic Unit (ALU) makes all calculations and comparisons. The ALU performs the arithmetic (+, -, *, /) and logical (AND, OR, NOT, XOR) operations sent from the memory and returns the result to the memory. The result of the logical operations is either true or false and helps the computer in decision-making.
The control unit controls the flow of data from input devices to memory and from memory to output devices. It controls and guides the interpretation, flow and manipulation of all data and information. It does not actually process the data, instead, it sends control signals to ALU and memory for carrying out the required operations.
Hardware refers to the physical or tangible components of a computer system. Examples include the CPU, monitor, keyboard, mouse, hard drive, and printer.
Software is the code or a set of instructions necessary to operate/run the computer hardware. It is intangible component of a computer. Examples include operating systems, applications, and programming languages.
Types of Operating systems are as follows:
Time-Sharing Operating System — Multiple users share system resources simultaneously, and the OS ensures that each user gets a slice of computing time. Examples, Unix.
Multi-User Operating System — Allows multiple users to access the computer resources simultaneously. Examples, Linux.
Single-User Operating System — Designed for one user to access the computer at a time. Examples, Windows 10, macOS.
Hardware refers to the physical components of a computer system, such as the CPU, memory, and storage devices, which provide the infrastructure for computing operations. However, without software — the programs and applications that instruct hardware how to function — these components cannot perform meaningful tasks. Conversely, software requires hardware to execute its instructions. Software encompasses operating systems, applications, and utilities that enable users to interact with computers and perform specific tasks. These programs rely on hardware to provide processing power, storage, and input/output capabilities necessary for running software effectively. Together, hardware and software make the computer system function.
Depending on the mode of interaction with hardware and functions to be performed, software can be broadly classified into three categories:
An operating system is an integrated set of programs that manages various resources and the overall operations of a computer system. It is designed to support the various activities of the computer system in a systematic way.
For example, Microsoft Windows, Linux, etc.
(a) Compiler — Programming Tool
(b) Assembler — Programming Tool
(c) Ubuntu — System Software
(d) Text Editor — Application Software
Memory devices are hardware components that store data or program instructions for a computer.
RAM (Random Access Memory) — It is a read/write memory as it is possible to both read from and write to a location within RAM. It is used for primary storage in computers to hold active information of data and instructions. The RAM is a volatile memory as it does not store data and instructions permanently and loses its contents when the power is switched off or interrupted. RAM provides faster access than secondary memory with less memory access time. The RAM chip in a computer can be categorized into two types:
ROM (Read-Only Memory) — It is a read-only memory, i.e., the data and instructions are placed in the ROM at the time of its manufacturing and cant be changed thereafter. It is a permanent and non-volatile memory as it does not lose its contents when the power is switched off or interrupted. It is slower than RAM and is used to hold certain essential instructions to check basic hardware components such as booting, procedures to load operating system and frequently needed functions. The different types of ROM available are:
Output devices are the devices that produce the output generated by the CPU in human understandable form, such as audio, video, text or hard copy, viz. printed documents.
For example: Visual Display Unit (VDU)/Monitor, LCD Screen, LED Screen, OLED, Printer, Speakers, Plotters etc.
RAM | ROM |
---|---|
Volatile Memory | Non-volatile Memory |
Can be written to and read from | Content can't be changed |
Touch screen is a type of display screen which allows interaction with computer through a touch-sensitive transparent panel covering the entire screen without any intermediate device. The touch screen uses a technology that enables the users to touch the screen with fingers to select objects.
Plotters are output devices that are used for producing high quality images, engineering drawings, architectural blueprints etc.
The different types of plotters are as follows:
The table with sizes for RAM and HDD of a computer:
Component | Bytes | Kilobytes (KB) | Megabytes (MB) | Gigabytes (GB) |
---|---|---|---|---|
RAM | 8,589,934,592 Bytes | 8,388,608 KB | 8,192 MB | 8 GB |
HDD | 549,755,813,888 Bytes | 536,870,912 KB | 524,288 MB | 512 GB |
The secondary storage devices available at school or home are as follow
(a) 2 MB — 2 MB * 1024 KB/MB * 1024 bytes/KB = 2 * 1024 * 1024 = 2,097,152 bytes
(b) 3.7 GB — 3.7 GB * 1024 MB/GB * 1024 KB/MB * 1024 bytes/KB = 3.7 * 1024 * 1024 * 1024 = 3,973,078,528 bytes
(c) 1.2 TB — 1.2 TB * 1024 GB/TB * 1024 MB/GB * 1024 KB/MB * 1024 bytes/KB = 1.2 * 1024 * 1024 * 1024 * 1024 = 1,319,843,208,192 bytes
(a) Memory requirement during translation — Interpreter requires less memory during translation, as it translates and executes code line by line. Compiler requires more memory during translation, as it translates the entire program at once before execution.
(b) Memory requirement after translation — Interpreter continues to require memory after translation, as it needs to re-translate every time the program is run. Compiler requires less memory after translation, as it produces an executable file that can be run independently.
(c) Number of instructions translated — Interpreter translates and executes one instruction at a time. Compiler translates the entire set of instructions at once, producing a complete machine code program.
Optical Discs use laser technology to read and write data. The data is encoded on the disc surface as tiny pits and lands, which are read by a laser beam.
Magnetic Discs use magnetic fields to store data. The data is recorded on a magnetic surface, such as that found in hard disk drives, in the form of magnetic patterns.
CD | DVD |
---|---|
CD stands for Compact Disc. | DVD stands for Digital Versatile Disc. |
The storage capacity varies from 650 MB to 900 MB. | A DVD can hold 4.7 GB to 17 GB of data. |
CDs are made of a polycarbonate disc with a reflective aluminum layer on one side. | DVDs are made of a polycarbonate disc with a reflective aluminum layer on both sides. |
CDs are more likely to be scratched or damaged, which can cause data loss. | DVDs are more durable than CDs as they have a protective layer on both sides of the disc. |
The statement "Functioning of a computer is similar to the way the human brain functions" compares how both systems process information. Computers use input devices like keyboards and mice to receive data, and output devices like monitors and printers to present results. Similarly, the human brain receives input through sensory organs such as the eyes, ears, and skin, and produces responses through actions and speech. Both systems use internal processes—computers use the CPU and memory for data handling, while the brain processes sensory information and stores memories.
A computer system comprises of five basic components:
An input unit takes the input and converts it into binary form which is directly understood by the computer.
Computers only understand binary language that uses just two symbols: 1 for ON and 0 for OFF. The input unit translates raw data from external sources into binary language that the computer understands. Without this conversion, the computer would not be able to understand or process the data provided.
There are mainly three components of a CPU:
Arithmetic and Logical Unit (ALU) — All calculations and comparisons are made in this unit. The ALU performs the arithmetic (+, -, *, /) and logical (AND, OR, NOT, XOR) operations sent from the memory, performs specific operations (addition, subtraction etc) and the result is returned to the memory. The result of the logical operations is either true or false and helps the computer in decision-making.
Control Unit (CU) — The CU controls the flow of data from input devices to memory and from memory to output devices. It controls and guides the interpretation, flow and manipulation of all data and information. It does not actually process the data, instead, it sends control signals to ALU and memory for carrying out the required operations.
Registers — These are high-speed temporary storage areas found in CPU. Registers work as per the instructions given by the control unit (CU), storing instructions and data immediately required for performing an operation. The CPU places the highest priority jobs/data inside registers for faster execution/processing. Registers can be of different sizes (16 bits, 32 bits, 64 bits and so on) and each register inside the CPU has a specific function like storing data, storing an instruction, storing address of a location in memory etc.
A control unit is referred to as the central controller of a computer because it controls the flow of data from input devices to memory and from memory to output devices. It controls and guides the interpretation, flow, and manipulation of all data and information, sending control signals to the Arithmetic Logic Unit (ALU) and memory to execute the required operations effectively.
Arithmetic Logic Unit (ALU) does not work independently; it operates in coordination with the control unit and memory. The control unit fetches instructions from memory and decodes them, directing the ALU to perform specific operations such as addition, subtraction, or logical comparisons. The results produced by the ALU are then stored back in memory or used by other components of the computer system.
Data | Information |
---|---|
Data refers to raw facts, figures, or values that are collected and stored without any specific context or interpretation. It is unprocessed and lacks meaning on its own. | Information is processed, organized, and meaningful data that has been analyzed, interpreted, and structured to provide context, relevance, and value. It is derived from data through analysis and is used to make decisions or gain insights. |
Data is unstructured, discrete. | Information is structured, organized. |
The output unit consists of output devices attached to the computer. These devices produce output generated by the CPU in a form that is readable and understandable by humans. The CPU processes data in binary form, and the output unit translates this data into text, images, audio, or other formats suitable for human interpretation.
Examples: Monitor, Printer, Speakers, Plotters etc.
The memory of the computer is like a predefined working space where it temporarily keeps information and data to facilitate its working. When the task is executed or finished, it clears the memory and this memory space is available for the next task to be executed or performed.
The block diagram of the computer system is shown below:
Input Unit — An input unit takes/accepts input and converts it into binary form so that it can be understood by the computer. The computer input constitutes data and instructions.
Central Processing Unit — CPU is the control centre or brain of a computer. It guides, directs, controls and governs all the processing that takes place inside the computer. There are mainly three components of a CPU:
Arithmetic and Logical Unit (ALU) — The ALU performs the arithmetic (+, -, *, /) and logical (AND, OR, NOT, XOR) operations sent from the memory, performs specific operations (addition, subtraction etc) and the result is returned to the memory.
Control Unit (CU) — The CU controls the flow of data from input devices to memory and from memory to output devices.
Registers — These are high-speed temporary storage areas found in CPU. Registers work as per the instructions given by the control unit (CU), storing instructions and data immediately required for performing an operation.
Memory Unit — Memory unit is used as a storage unit for program as well as data. The memory can be both primary and secondary depending upon its location in the computer system. The primary memory, also termed as main memory, is directly accessible to the CPU since all the work is done in the RAM and later on gets stored on the secondary storage. On the contrary, the secondary memory, also known as auxiliary memory, can be accessed by the CPU through input-output controllers or units.
Output Unit — Output unit is formed by the output devices attached to the computer. Output devices produce the output generated by the CPU in human readable form.
Volatile Memory | Non-Volatile Memory |
---|---|
Data is lost when power is turned off. | Data is retained even when power is turned off. |
It has faster access speeds. | It has slower access speeds. |
It is used for primary memory in computers. | It is used for long-term storage. |
It provides temporary storage for data and instructions currently being processed. | It provides permanent storage for data and programs. |
It is essential for the smooth functioning of the computer during active tasks. | It is essential for storing data over long periods and for booting the system. |
Examples: RAM (Random Access Memory). | Examples: Hard disk drives (HDD), Solid State Drives (SSD), Read Only Memory (ROM). |
Primary storage devices refer to the main memory in a computer that is directly accessible by the CPU. This memory is used to temporarily store data and instructions that the CPU needs while performing tasks.
The primary storage devices are classified into two types:
A mouse is a pointing device with a roller at its base, used for moving a pointer on a computer monitor.
The different types of mouse are as follows:
A barcode is a collection or a sequence of lines of different heights and widths that are printed on various types of products. The machine that reads these barcodes is called a barcode reader. A barcode reader is used to convert the information encoded in a barcode into a digital format that can be processed by a computer system.
Inkjet Printers — An inkjet printer is the most common type of low-cost printer. It uses the technique of spreading quick dry ink on paper. The ink is stored in the form of cartridges of different colours. These printers generate high quality prints and are ideal for small offices and homes.
Laser Jet Printers — These printers use laser technology to produce printed documents. These are very fast printers and are used for high quality prints.
Plotters are the output devices that are used for producing high quality images, engineering drawings, architectural blueprints, maps etc.
Benefits of using Plotters are as follows:
Limitations of using Plotters are as follows:
The three types of input devices are as follows:
Keyboard — A keyboard is the input device which directly enters the data in the form of letters, digits and commands into the computer. QWERTY keyboard is the commonly-used keyboard.
Mouse — A mouse is a pointing device with a roller at its base, used for moving a pointer on a computer monitor. It converts the movements of the user's hand into a unique set of binary digits representing the position of the mouse at a particular instant. When a user moves a mouse across a flat surface, the pointer moves in the direction of the mouse's movement.
Light Pen — A light pen is a pointing device that can be used to select anything on the computer screen by simply pointing at it or for drawing figures directly on the screen. It consists of a photocell mounted on a pen-shaped tube called stylus. It is capable of sensing a position on the screen when its tip touches the screen. Clicking is performed by pressing the pen on the screen. A light pen is mostly used by engineers, architects or designers.
A Visual Display Unit (VDU) commonly known as monitor, is the most common device for displaying the output of the computer-processed information.
The two types of VDU are as follows:
Impact Printers | Non-Impact Printers |
---|---|
It forms characters by striking a print hammer against an inked ribbon. | It forms characters without making direct contact with the paper. |
It uses either ribbon or carbon paper. | It uses ink cartridges. |
It makes noise while printing. | It prints smoothly on the paper. |
(a) Light Pen — A light pen is a pointing device that can be used to select anything on the computer screen by simply pointing at it or for drawing figures directly on the screen. It consists of a photocell mounted on a pen-shaped tube called stylus. It is capable of sensing a position on the screen when its tip touches the screen. Clicking is performed by pressing the pen on the screen. A light pen is mostly used by engineers, architects or designers.
(b) Graphic Tablet — A graphic tablet is an input device with a touch-sensitive surface that allows users to create digital art and designs. It comes with a stylus that mimics traditional drawing tools. Graphic tablets connect to computers via USB or Bluetooth, facilitating precise digital artwork, photo editing, 3D modelling, and handwriting.
(c) CD-ROM — It is a thin optical disc which is commonly used to store audio and video data. The capacity of a standard 120 mm CD is 700 MB. Originally, CD-ROM drives had transfer rate of only 150 KB/s which was very low. The latest CD-ROM drives can transfer up to 10800 KB/sec.
(d) DVD — Digital Versatile Disc or Digital Video Disc is an optical disc storage device. It can be recorded on one or both sides. Its capacity may range from 4.7 GB to 17.08 GB.
Digital computers can be classified into four major categories based on their size, power, and functionality:
Microcomputers (Personal Computers) — These are small, relatively inexpensive computers designed for individual use. They have a microprocessor, memory (RAM and ROM), and storage devices. Examples: Desktop computers, laptops, tablets, and smartphones.
Minicomputers — These are mid-sized computers that are more powerful than microcomputers but less powerful than mainframes. They can support multiple users simultaneously and are used in small to medium-sized businesses. Examples: DEC PDP-11.
Mainframe Computers — These are large, powerful, and expensive computers used mainly by large organizations for critical applications, bulk data processing, and large-scale transaction processing. They can handle and process vast amounts of data simultaneously and can support hundreds or thousands of users at once. Examples: IBM zSeries.
Supercomputers — These are the most powerful computers in terms of processing capacity and are used for highly complex computations. They are used for scientific and engineering applications, like weather forecasting, nuclear simulations, and complex biological computations. Examples: Cray XT5, IBM Summit.
Some of the common secondary storage devices are as follows:
Hard Disk — A hard-disk is a non-volatile, high capacity storage device ranging from 1 Gigabyte to several Terabytes. It consists of solid rounded disks, packed on one another, made up of a magnetic material and sealed inside a case. In a hard disk, data is stored on spinning magnetic disks called platters. Each platter is divided into tracks and sectors.
Blu-ray Disc (BD) — A Blu-ray Disc is a high-capacity optical disk medium developed for recording, rewriting and playing back high-definition video. It uses blue laser that permits large amount of data to be stored at a greater density. They support higher resolutions and more advanced video and audio formats as compared to DVDs.
Compact Disc (CD) — It is a thin optical disc which is commonly used to store audio and video data. The capacity of a standard 120 mm CD is 700 MB. Originally, CD-ROM drives had transfer rate of only 150 KB/s which was very low. The latest CD-ROM drives can transfer up to 10800 KB/sec.
Magnetic Tapes — In this, magnetic coatings are stored as data on a thin tape. Data read/write speed is slower because of sequential access. They are convenient, secure and affordable.
DVD — Digital Versatile Disc or Digital Video Disc is an optical disc storage device. It can be recorded on one or both sides. Its capacity may range from 4.7 GB to 17.08 GB.
USB Pen Drive — This is a small, portable memory which can be plugged into a computer with USB Port. A pen drive's capacity is less than that of the hard disk but much higher than a floppy or CD. It is more reliable also. Pen drives have a storage capacity of 2GB, 4GB, 8GB, 16GB, 32GB and 64GB, up to 2TB.
Memory Cards — These are data storage devices, also called Flash memory cards. They are mainly used with digital cameras, computers, mobile phones, music players, video game consoles etc. They offer high recording ability with power-free storage. Memory cards come with a storage capacity of 8GB, 16GB, 32GB, 64GB and 128GB, up to 1.5TB.
Memory cards are small, portable storage devices used to store data, such as photos, videos, music, and other files, in electronic devices like cameras, smartphones, tablets, and laptops and are also called flash cards.
The types of memory cards are as follows:
Secure Digital (SD) cards — SD cards are widely used in cameras, smartphones, and other devices. They come in various capacities, from a few hundred megabytes to several gigabytes.
MicroSD cards — A smaller version of SD cards, microSD cards are used in devices like smartphones, tablets, and action cameras.
CompactFlash (CF) cards — CF cards are larger and faster than SD cards, making them suitable for professional photographers and high-end cameras.
(a) Assembler — Assembler is used to translate the program written in assembly language into machine code. The input of assembler is a source program that contains assembly language called mnemonics. The output generated by the assembler is the object code or machine code which is understandable by the computer.
(b) Compiler — The language processor that translates the complete source program as a whole in one go into machine code is called compiler.
(c) Interpreter — The language processor that translates a single statement of source program into machine code and executes it immediately before moving on to the next line is called interpreter. If there is an error in the statement, the interpreter terminates its translating process at that statement and displays an error message.
Secondary memory provides permanent storage for data and information needed for future use. It allows users to store large amounts of data systematically and retrieve it as required. Additionally, it retains data and programs even when the computer is turned off.
RAM (Random Access Memory) is needed for temporary storage of data and instructions that the CPU uses actively. It provides faster access than secondary memory with less memory access time.
ROM (Read-Only Memory) is needed for permanent storage of data. It is used to hold certain essential system instructions to check basic hardware components such as booting, procedures to load operating system and frequently needed functions.
True
Reason — The Control unit controls flow of data from input devices to memory and from memory to output devices. It sends control signals to ALU and memory for carrying out the required operations.
True
Reason — A light pen is a pointing device, basically a stylus, that can be used to select anything on the computer screen by simply pointing at it or for drawing figures directly on the screen.
True
Reason — An operating system (OS) acts as an interface between the user, computer hardware and software. It manages hardware resources, facilitates user interaction, and provides necessary services for running application software.
True
Reason — A computer can perform a wide range of tasks, including complex calculations, logical functions, data processing, and running various applications. In contrast, a calculator is primarily designed for arithmetic and simple geometrical operations.