<h5 id="11-introduction-to-computer-system">1.1 INTRODUCTION TO COMPUTER SYSTEM</h5> <ul> <li>A computer is an electronic device that can be programmed to accept data, process it, and generate results.</li> <li>A computer system includes a CPU, memory, input/output devices, and storage devices.</li> <li>The components of a computer system function together as a single unit.</li> <li>Computer systems come in various forms and sizes, from servers to smartphones.</li> <li>A computer would be considered intelligent if it could deceive a human into believing it was human (Turing, 1950).</li> </ul> <p>======</p> <h5 id="111-central-processing-unit-cpu">1.1.1 Central Processing Unit (CPU)</h5> <ul> <li>The Central Processing Unit (CPU) is the electronic circuitry of a computer that processes instructions and data.</li> <li>It is commonly referred to as the brain or processor of a computer and can be found on one or more microchips called integrated circuits (ICs).</li> <li>The CPU is composed of registers, an Arithmetic Logic Unit (ALU), and a Control Unit (CU).</li> <li>Registers are local memory storage locations on the CPU chip used for storing data, instructions, or intermediate results.</li> <li>The ALU performs arithmetic and logic operations, while the CU controls sequential instruction execution, interprets instructions, and manages data flow between the memory, ALU, and input/output devices.</li> </ul> <p>======</p> <h5 id="112-input-devices">1.1.2 Input Devices</h5> <ul> <li>Input devices are peripherals that convert input data into a digital form readable by a computer system.</li> <li>Examples include keyboard, mouse, scanner, touch screen, braille keyboard for visually impaired, and voice input like Google voice search.</li> <li>Data entered through input devices is temporarily stored in the computer’s main memory (RAM).</li> <li>For permanent storage, data and instructions are saved in additional storage locations called secondary memory.</li> <li>Figure 1.2 illustrates various input devices.</li> </ul> <p>======</p> <h5 id="113-output-devices">1.1.3 Output Devices</h5> <ul> <li>Output devices are devices that receive data from a computer system for display, physical production, etc., and convert digital information into human-understandable forms.</li> <li>Examples of output devices include monitors, projectors, headphones, speakers, printers, and braille display monitors.</li> <li>Printers are commonly used output devices that create physical copies of digital data. Types of printers include inkjet, laserjet, dot matrix, and 3D printers.</li> <li>3D printers are used in manufacturing industries to create prototypes of products and are being explored for use in the medical field for developing body organs.</li> <li>A punched card is a type of output device that stores digital data in the form of holes at predefined positions.</li> </ul> <p>======</p> <h5 id="12-evolution-of-computer">1.2 EVOLUTION OF COMPUTER</h5> <ul> <li> <p>The evolution of computing devices has occurred rapidly, with significant advancements from simple calculators to powerful data processors.</p> </li> <li> <p>The Von Neumann architecture, which consists of a CPU, memory, input/output devices, and communication channels, is a fundamental concept in computing technology. ENIAC, the first binary programmable computer based on this architecture, was developed in the 1940s.</p> </li> <li> <p>In the 1970s, Large Scale Integration (LSI) allowed for the integration of complete CPUs on a single chip, known as a microprocessor. This was followed by the introduction of Moore’s Law, which predicted exponential growth in the number of transistors that could be assembled in a single microchip.</p> </li> <li> <p>The introduction of personal computers (PCs) in the 1980s, such as the IBM PC and Apple Macintosh, along with the surge in Graphical User Interface (GUI) based operating systems, further popularized the use of computers. The growth of the World Wide Web in the 1990s made computers an indispensable part of everyday life.</p> </li> <li> <p>With advancements in processor miniaturization, faster memory, and high-speed data and connectivity mechanisms, personal computing has become portable through laptops, smartphones, tablets, and other personal digital assistants. The future of computing includes wearable gadgets and smart appliances that are part of the Internet of Things (IoT), leveraging the power of Artificial Intelligence (AI).</p> </li> </ul> <p>======</p> <h5 id="13-computer-memory">1.3 COMPUTER MEMORY</h5> <ul> <li>A computer system requires memory for storing data and instructions for processing.</li> <li>The main memory, also known as primary memory, is the memory typically referred to when discussing a computer’s memory.</li> <li>Secondary memory, also called a storage device, is used for permanent data, instruction, and result storage, for future use.</li> <li>The main memory is volatile, meaning it loses all data when power is removed, while secondary memory is non-volatile and retains data.</li> <li>The main memory is faster than secondary memory, allowing for quicker data access during processing.</li> </ul> <p>======</p> <h5 id="131-units-of-memory">1.3.1 Units of Memory</h5> <ul> <li>KB (Kilobyte) is a unit of digital information, with 1 KB equal to 1024 Bytes.</li> <li>The larger units of digital information include: <ul> <li>MB (Megabyte): 1 MB = 1024 KB</li> <li>GB (Gigabyte): 1 GB = 1024 MB</li> <li>TB (Terabyte): 1 TB = 1024 GB</li> <li>PB (Petabyte): 1 PB = 1024 TB</li> <li>EB (Exabyte): 1 EB = 1024 PB</li> <li>ZB (Zettabyte): 1 ZB = 1024 EB</li> <li>YB (Yottabyte): 1 YB = 1024 ZB</li> </ul> </li> <li>The relationships between these units and their respective byte values follow a similar pattern, with each unit being 1024 times larger than the previous one.</li> <li>These units are commonly used to measure the storage capacity of digital devices and the size of digital files and datasets.</li> </ul> <p>======</p> <h5 id="132-types-of-memory">1.3.2 Types of Memory</h5> <ul> <li>Human memory is categorized into two types: primary and secondary.</li> <li>Primary memory is further divided into Random Access Memory (RAM) and Read Only Memory (ROM). RAM is volatile and used for temporary data storage, while ROM is non-volatile and stores rarely changed contents.</li> <li>Cache memory, a high-speed memory between the CPU and primary memory, stores copies of frequently accessed primary memory data to reduce average data access time.</li> <li>Secondary memory, with larger storage capacity and non-volatile nature, is used for permanently storing data or instructions. It includes devices like Hard Disk Drive (HDD), CD/DVD, Memory Card, and Solid State Drive (SSD).</li> <li>Secondary memory devices support fast data transfer speed and have become simpler to transfer data between computers due to portable flash or pen drives.</li> </ul> <p>======</p> <h5 id="14-data-transfer-between-memory-and-cpu">1.4 DATA TRANSFER BETWEEN MEMORY AND CPU</h5> <ul> <li> <p>Data transfer between different components of a computer system is done using physical wires called bus.</p> </li> <li> <p>The system bus is made up of three types of buses: data bus, address bus, and control bus.</p> </li> <li> <p>The data bus is used to transfer data between different components, the address bus transfers addresses between CPU and main memory, and the control bus communicates control signals between different components.</p> </li> <li> <p>The CPU interacts directly with main memory, and data is transferred between the CPU and main memory using the bus. The memory controller manages the flow of data into and out of the computer’s main memory.</p> </li> <li> <p>The data bus is bidirectional, while the control bus and address bus are unidirectional. The CPU places the data on the data bus to write data into memory, and a dedicated hardware, the memory controller, places the data on the data bus during read operations.</p> </li> </ul> <p>======</p> <h5 id="15-microprocessors">1.5 MICROPROCESSORS</h5> <ul> <li>The text outlines the evolution of microprocessors through five generations.</li> <li>The first generation (1971-73) used LSI (Large Scale Integration) technology with an 8-bit data width and 1 KB of memory, operating at 108-200 KHz.</li> <li>The second generation (1974-78) also used LSI technology but with an 8-bit data width and 1 MB of memory, operating at up to 2 MHz.</li> <li>The third generation (1979-80) used VLSI (Very Large Scale Integration) technology with a 16-bit data width and 16 MB of memory, operating at 4-6 MHz.</li> <li>The fourth generation (1981-95) used VLSI technology with a 32-bit data width and 4 GB of memory, operating at up to 133 MHz.</li> <li>The fifth generation (1995-present) uses SLSI (Super Large Scale Integration) technology with a 64-bit data width and 64 GB of memory, operating at 533 MHz-34 GHz, and features multicore processors.</li> </ul> <p>======</p> <h5 id="151-microprocessor-specifications">1.5.1 Microprocessor Specifications</h5> <ul> <li>Word Size: Refers to the maximum number of bits a microprocessor can process at a time. It has increased from 8 bits in early microprocessors to the current maximum of 64 bits.</li> <li>Memory Size: Varies depending on the word size. Initial RAM was small (4MB) due to the 4/8-bit word size, but with the increase in word size to 64 bits, it has become feasible to use RAM of up to 16 Exabytes (EB).</li> <li>Clock Speed: Computers have an internal clock that generates pulses at regular intervals. Earlier measured in Hertz (Hz) and Kilohertz (kHz), it is now measured in Gigahertz (GHz), indicating the number of pulses per second the clock can generate.</li> <li>Cores: Earlier processors had only one computation unit, but with the advent of multicore processors, it has become possible for computers to execute multiple tasks simultaneously, increasing system performance. CPUs with two, four, and eight cores are called dual-core, quad-core, and octa-core processors, respectively.</li> </ul> <p>======</p> <h5 id="152-microcontrollers">1.5.2 Microcontrollers</h5> <ul> <li>A microcontroller is a compact computing device with a CPU, RAM, ROM, and peripherals on a single chip.</li> <li>Examples include keyboards, washing machines, digital cameras, and remote controllers.</li> <li>Microcontrollers are designed for specific tasks, reducing their size and cost.</li> <li>They are embedded in devices or systems to perform specific functions automatically.</li> <li>For instance, a microcontroller in a washing machine controls the washing cycle without human intervention.</li> </ul> <p>======</p> <h5 id="16-data-and-information">1.6 DATA AND INFORMATION</h5> <ul> <li>A computer’s primary function is to process data.</li> <li>Data can include various forms such as instructions, pictures, songs, videos, documents, etc.</li> <li>Data can be raw and unorganized facts that, when processed, can provide meaningful information.</li> <li>Information and knowledge are not the same as data; they are derived from data.</li> <li>Understanding data is crucial as it forms the basis of computer system operations.</li> </ul> <p>======</p> <h5 id="161-data-and-its-types">1.6.1 Data and Its Types</h5> <ul> <li>The text provides attendance records of three students from Class XI.</li> <li>The students are named Sohan, Sheen, and Geet.</li> <li>The attendance for the month of July is given for Sohan (65%) and Sheen (85%).</li> <li>The attendance for the months of May (82%) and July (94%) is given for Geet.</li> <li>Figure 1.11 displays a semi-structured data format of the total attendance record maintained by the school.</li> </ul> <p>======</p> <h5 id="162-data-capturing-storage-and-retrieval">1.6.2 Data Capturing, Storage and Retrieval</h5> <ul> <li>Data Capturing: It is the process of gathering data in digital form from various sources like keyboard, barcode readers, social media, remote sensors, etc. Heterogeneity among data sources can make data capturing complex.</li> <li>Data Storage: It involves storing the captured data for future processing. With the increasing rate of data production, data storage has become challenging. There are numerous digital storage devices available, and the storage devices need to be upgraded periodically to accommodate the increasing data.</li> <li>Data Retrieval: It is the process of fetching data from storage devices for processing as per user requirement. Minimizing data access time is crucial for faster data processing.</li> <li>Digital storage devices: There are various digital storage devices available in the market, including hard disk drives, solid-state drives, compact discs, USB drives, etc.</li> <li>Data servers: In large organizations, computers with larger and faster storage called data servers are deployed to store vast amounts of data, helping in processing data efficiently. However, the cost of setting up and maintaining a data server is high, especially for small organizations and startups.</li> </ul> <p>======</p> <h5 id="163-data-deletion-and-recovery">1.6.3 Data Deletion and Recovery</h5> <ul> <li>Digital data can be deleted accidentally by users, intentionally by hackers or malware, or due to storage device malfunction or crash.</li> <li>When data is deleted, its address entry is marked as free, and the space is shown as empty to the user, without actually deleting the data.</li> <li>Data recovery is possible if the contents or memory space marked as deleted have not been overwritten by other data. It is a process of retrieving deleted, corrupted, and lost data from secondary storage devices.</li> <li>To avoid unauthorized data deletion, limiting access to the computer system and using passwords for user accounts and files is recommended. Encrypting files can also protect them from unwanted modification.</li> <li>To mitigate the risk of unwanted recovery of data, properly deleting or shredding data before disposing of any old or faulty storage device is essential. This prevents mischief-mongers from recovering data from such devices, ensuring data confidentiality.</li> </ul> <p>======</p> <h5 id="17-software">1.7 SOFTWARE</h5> <ul> <li>Software is the set of instructions that operates computer hardware.</li> <li>It is intangible and includes instructions and data to be processed by the computer.</li> <li>Software and hardware work together to complete tasks; each software is written for a specific computational purpose.</li> <li>Examples of software include operating systems, word processing tools, video players, and photo editors.</li> <li>A document or image stored digitally is referred to as a soft-copy, and its printed version is called a hard-copy.</li> </ul> <p>======</p> <h5 id="171-need-of-software">1.7.1 Need of Software</h5> <ul> <li>The primary function of software is to make computer hardware useful and operational.</li> <li>Software acts as an interface between human users and the hardware, enabling communication between different hardware components and with end-users.</li> <li>Software can be classified into three categories based on the mode of interaction with hardware and functions to be performed: system software, programming tools, and application software.</li> <li>Hardware refers to the physical components of the computer system, while software is a set of instructions and data that makes hardware functional.</li> <li>Examples of hardware include RAM, keyboard, printer, monitor, CPU, etc.</li> </ul> <p>======</p> <h5 id="172-system-software">1.7.2 System Software</h5> <ul> <li>System software is a type of software that operates and manages computer hardware.</li> <li>The Operating System (OS) is a fundamental system software that runs a computer and manages other application programs. Popular OS include Windows, Linux, and Macintosh.</li> <li>System Utilities are software used for maintenance and configuration of computer systems. Examples include disk defragmentation tools, formatting utilities, and system restore utilities.</li> <li>Other system utilities, not shipped with the OS, improve system performance, such as anti-virus software and disk cleaner tools.</li> <li>Device Drivers ensure proper functioning of specific devices by acting as an interface between the device and the operating system. They are responsible for managing and controlling a device’s hardware level operations.</li> </ul> <p>======</p> <h5 id="173-programming-tools">1.7.3 Programming Tools</h5> <ul> <li>Programming languages are used to give instructions to computers in a form they can understand.</li> <li>There are two major categories of programming languages: low-level languages (machine language and assembly language) and high-level languages (e.g., C++, Java, Python).</li> <li>Low-level languages are machine-dependent, while high-level languages are machine-independent and easier for humans to understand.</li> <li>Translators, such as assemblers, compilers, and interpreters, are needed to convert high-level and assembly language codes into machine language.</li> <li>Integrated Development Environments (IDEs), like Python IDLE, Netbeans, and Eclipse, simplify program development by providing text editors, building tools, and debuggers in a single software.</li> </ul> <p>======</p> <h5 id="174-application-software">1.7.4 Application Software</h5> <ul> <li>Application software is a type of software that works on top of system software to cater to the different requirements of end-users.</li> <li>There are two broad categories of application software: general-purpose and customized software.</li> <li>General-purpose software, such as Calc of LibreOffice, Adobe Photoshop, and Mozilla web browser, are developed for generic applications and can be used by any computer user.</li> <li>Customized software, such as websites and school management software, are tailor-made to meet the specific needs of an individual or organization.</li> <li>A computer system can function without application software, but it cannot operate without system software.</li> </ul> <p>======</p> <h5 id="175-proprietary-or-free-and-open-source-software">1.7.5 Proprietary or Free and Open Source Software</h5> <ul> <li> <p>Free and Open Source Software (FOSS) is software whose source code is freely available to the public for development and improvement.</p> </li> <li> <p>Examples of FOSS include Ubuntu, Python, Libreoffice, Openoffice, and Mozilla Firefox.</p> </li> <li> <p>Freeware is software that is freely available for use but whose source code is not available.</p> </li> <li> <p>Freeware examples include Skype and Adobe Reader.</p> </li> <li> <p>Proprietary software is software that must be purchased from the vendor who holds the copyright.</p> </li> <li> <p>Examples of proprietary software include Microsoft Windows, Tally, and Quickheal.</p> </li> </ul> <p>======</p> <h5 id="18-operating-system">1.8 OPERATING SYSTEM</h5> <ul> <li>An operating system (OS) is a resource manager that manages computer hardware and software resources.</li> <li>The primary objectives of an OS are to provide services for building and running application programs and to provide a user interface.</li> <li>The OS decides the order of execution for multiple application programs.</li> <li>It loads application programs into memory and allocates them to the CPU for execution.</li> <li>Popular operating systems include Windows, Linux, Android, and Macintosh.</li> </ul> <p>======</p> <h5 id="181-os-user-interface">1.8.1 OS User Interface</h5> <ul> <li> <p>The user interfaces of an OS can be of different types, each providing unique functionality.</p> </li> <li> <p>Command-based interface requires users to enter commands for tasks, using the keyboard as primary input. It is less interactive and allows running only one program at a time. (Examples: MS-DOS, Unix)</p> </li> <li> <p>Graphical User Interface (GUI) lets users interact through icons, menus, and visual options. It uses the mouse and keyboard as input devices. (Examples: Microsoft Windows, Ubuntu, Fedora, Macintosh)</p> </li> <li> <p>Touch-based Interface allows interaction through touch input, commonly used in smartphones, tablets, and PCs. (Examples: Android, iOS, Windows 8.1, 10)</p> </li> <li> <p>Voice-based Interface is designed for users with special needs, allowing interaction through voice commands. (Examples: iOS (Siri), Android (Google Now or “OK Google”), Microsoft Windows 10 (Cortana))</p> </li> <li> <p>Gesture-based Interface is an emerging technology, allowing interaction through gestures like waving, tilting, eye motion, and shaking. (Examples: some Android and iOS based smartphones, laptops)</p> </li> </ul> <p>======</p> <h5 id="182-functions-of-operating-system">1.8.2 Functions of Operating System</h5> <ul> <li>The operating system, as a resource manager, manages different resources like main memory, CPU, I/O devices, ensuring optimal use and preventing system performance degradation.</li> <li>Process Management: The operating system manages multiple processes, allocates CPU among processes, and handles the management of multiple tasks, resource allocation, and information exchange between processes.</li> <li>Memory Management: The operating system dynamically allocates and frees memory for running processes in the limited main memory, while keeping track of memory locations as free or occupied, making the most efficient use of memory space.</li> <li>File Management: The operating system manages files in secondary storage, creating, updating, deleting, and protecting files, with protection being a crucial function for multiple users. This function manages secondary memory, while memory management handles the main memory.</li> <li>Device Management: The operating system manages heterogeneous I/O devices and hardware, interfacing with device drivers and related software, providing configuration options, and restricting device access to authorized users, software, and hardware.</li> </ul> <p>======</p>