Operating System Concepts PDF

GROUP 1 PT 101 Prepared by: JIPAU LONUDA OPERATING SYSTEM  OPERATING SYSTEM An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer....

GROUP 1 PT 101 Prepared by: JIPAU LONUDA OPERATING SYSTEM  OPERATING SYSTEM An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer. Examples: PUNCH CARD  MEMORY MANAGEMENT It is the management of the main or primary memory. Whatever program is executed, it has to be present in the main memory. Its main objective is to effectively use currently available memory to facilitate the execution of processes and applications.  PROCESSING MANAGEMENT Process management is a key feature of an operating system that handles the creation, planning, execution, and termination of processes or tasks within a computer system.  FILE SYSTEM MANAGEMENT The File Manager (or File Management System) is the manager in the Operating System that creates the illusion that there are files and folders being stored in computer memory. FILE SYSTEM MANAGEMENT  DEVICE MANAGEMENT Device management functions are nothing but managing any physical or virtual device’s operation, implementation, and maintenance.  SECURITY AND PROTECTION For security, modern operating systems employ a firewall. A firewall is a type of security system that monitors all computer activity and blocks it if it detects a threat  JOB ACCOUNTING As the operating system keeps track of all the functions of a computer system. Hence, it makes a record of all the activities taking place on the system. It has an account of all the information about the memory, resources, errors, etc.  ERROR DETECTING AIDS Error detection guarantees that data is delivered reliably across susceptible networks. The operating system continuously monitors the system to locate or recognize problems and protects the system from them.  CO-ORDINATION BETWEEN SOFTWARE AND USERS The operating system (OS) allows hardware components to be coordinated and directs and allocates assemblers, interpreters, compilers, and other software to different users of the computer system.  BATCH OPERATING SYSTEM In this system, the OS does not forward the jobs/tasks directly to the CPU. It works by grouping together similar types of jobs under one category. Further, we name this group as a ‘batch’. Hence, the name batch OS. Examples: The payroll system, bank statement, etc.  MULTIPROGRAMMED OPERATING SYSTEM A Multiprogramming operating system is an operating system that supports the running of numerous programs simultaneously on a single processor machine. If one program waits for an input/ output transfer, the other programs are ready to utilize the CPU. Examples:Download software, transfer data, Google Chrome, MS-Excel, Firefox browser  MULTIPROCESSING OPERATING SYSTEM Multiprocessor operating systems are used in operating systems to boost the performance of multiple CPUs within a single computer system. Multiple CPUs are linked together so that a job can be divided and executed more quickly.  DISTRIBUTED OPERATING SYSTEM Distributed operating systems allow users to access distributed resources across multiple locations easily. These systems also facilitate using distributed file systems, computing, and data processing Examples : LOCUS etc  MULTITASKING OPERATING SYSTEM A multitasking operating system is a type of system software that enables a computer to execute multiple tasks or processes simultaneously.  TIME SHARING OPERATING SYSTEM A time-sharing operating system, also called a multi-user operating system, enables several users to engage with the computer simultaneously. Examples are UNIX etc.  REAL-TIME OPERATING SYSTEM(ROTS) In these systems, the time interval for processing and responding to inputs is very small. Therefore, due to this quality, these are used in real- time situations. For example in missile systems, robots, etc.  TWO CATEGORIES OF REAL-TIME OPERATING SYSTEM(ROTS) HARD REAL-TIME SYSTEMS SOFT REAL-TIME SYSTEMS In this, the time constraint In this, the time constraint is very short and strict. is not so short and strict. Even seconds of delay is not acceptable. EXAMPLES OF OPERATING SYSTEM  LINUX Linux is, in simplest terms, an operating system. It is the software on a computer that enables applications and the computer operator to access the devices on the computer to perform desired functions. LINUX OPERATING SYSTEM LINUS TROVALDS  LINUX OPERATING SYSTEM ADVANTAGES DISADVANTAGES - Free to use. -Harder to learn for - Can be changed easily beginners. to fit your needs. - Some software doesn't work, especially popular - Very safe and secure. programs. - Works well on old -Fewer games compared to computers. Windows.  macOS macOS is an operating system developed by Apple for its Mac computers. It provides a graphical user ainterface (GUI) and allows users to run applications, manage files, and interact with their computers efficiently  macOS STEVE JOBS  MAC OPERATING SYSTEM ADVANTAGES DISADVANTAGES - Runs smoothly on Apple - Expensive because you devices. need to buy Apple - Very safe and less likely computers. to get viruses. - Fewer options for games - Great for creative work and software. (like graphic design and - Hard to change the video editing). computer parts.  EMBEDDED OPERATING SYSTEM WINDOWS Windows is an operating system created by Microsoft that allows you to use and manage your computer through a visual interface with icons, windows, and menus.  WINDOWS OPERATING EMBEDDED OPERATING SYSTEM SYSTEM BILL GATES  WINDOWS OPERATING SYSTEM ADVANTAGES DISADVANTAGES - Works well with most - Less secure (more likely software and hardware. to get viruses). - Easy to use for most - Costs money to buy a people. license. - A lot of software options - Can use a lot of computer including games and office power. tools. NETWORKING  NETWORK A computer network (AKA a data network) is a series of computers connected to each other, whether by cables or wirelessly, that allow for effective communication. TYPES OF NETWORK  PERSONAL AREA NETWORK A Personal area network (PAN) connects electronic devices within a user's immediate are.  METROPOLITAN AREA NETWORK The operating system will collect consumption statistics for various resources and monitor performance indicators such as reaction time, which is the time between requesting a service and receiving a response from the system.  LOCAL AREA NETWORK Is a group of computers and peripheral devices that are connected together within a distinct geographic area, such as an office building or campus.  WIDE AREA NETWORK -A Wide area network (also known as WAN), is a large network of information that is not tied to a single location.  NETWORK PROTOCOLS A network protocol is a set of established rules that specify how to format, send and receive data so that computer network endpoints, including computers, servers, routers and virtual machines, can communicate despite differences in their underlying infrastructures, designs or standards.  1.Transmission Control Protocol (TCP) TCP is a foundational protocol that operates at the transport layer of the OSI model. It guarantees the reliable and ordered delivery of data packets between devices.  2. Internet Protocol (IP) Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the internet.  3. Hypertext Transfer Protocol is a protocol used for transferring web pages and other resources on the World Wide Web.  4. Simple Mail Transfer Protocol (SMTP) Is a protocol for sending and receiving email. It enables the transfer of email messages from a client to a server or between servers.  5. Post Office Protocol (POP) and Internet Message Access Protocol (IMAP) are protocols used by email clients to retrieve messages from a server.  6. File Transfer Protocol (FTP) Is a protocol designed for transferring files between computers.  7. Simple Network Management Protocol (SNMP) Is a protocol used for managing and monitoring network devices, such as routers, switches, and servers.  8. Domain Name System (DNS) Is a protocol that translates human-readable domain names into IP addresses.  9. Dynamic Host Configuration Protocol (DHCP) Is a protocol that automates the process of assigning IP addresses to devices on a network.  CPU SCHEDULING -CPU scheduling is the process of deciding which process will own the CPU to use while another process is suspended. -The main function of the CPU scheduling is to ensure that whenever the CPU remains idle, the OS has at least selected one of the processes available in the ready-to-use line.  TERMINOLOGIES IN CPU SHEDULING Arrival Time: Time at which the process arrives in the ready queue. Completion Time: Time at which process completes its execution. Burst Time: Time required by a process for CPU execution. Turn Around Time: Time Difference between completion time and arrival time. -Turn Around Time = Completion Time – Arrival Time Waiting Time(W.T): Time Difference between turn around time and burst time. -Waiting Time = Turn Around Time – Burst Time  Two Types of CPU Scheduling Preemptive Scheduling: Preemptive scheduling is used when a process switches from running state to ready state or from the waiting state to the ready state. Non-Preemptive Scheduling: Non-Preemptive scheduling is used when a process terminates , or when a process switches from running state to waiting state. Two Types of CPU Scheduling Examples of Non-Preemptive Scheduling Algorithm  First Come First Serve (FCFS) -FCFS is the simplest scheduling algorithm. There is a single rule; schedule the first process to arrive, and let it run to completion.  Shortest Job First Scheduling Shortest job first (SJF) is a scheduling process that selects the waiting process with the smallest execution time to execute next.  Longest Job First Scheduling -Longest Job First(LJF) scheduling process is just opposite of shortest job first (SJF), as the name suggests this algorithm is based upon the fact that the process with the largest burst time is processed first.  Highest Response Ratio Next Highest Response Ratio Next is a non-preemptive CPU Scheduling algorithm and it is considered as one of the most optimal scheduling algorithms. Response Ratio = (W + S)/S Here, W is the waiting time of the process so far and S is the Burst time of the process. Examples of Preemptive Scheduling Algorithm  Priority Scheduling -Preemptive Priority CPU Scheduling Algorithm is a pre-emptive method of CPU scheduling algorithm that works based on the priority of a process.  Round Robin Scheduling Round Robin is a CPU scheduling algorithm where each process is cyclically assigned a fixed time slot. It is the preemptive version of First come First Serve CPU Scheduling algorithm. Quantom time= 5 ms  Shortest Remaining Job Scheduling Shortest remaining time first is the preemptive version of the Shortest job first which we have discussed earlier where the processor is allocated to the job closest to completion.  Longest Job Remaining -The longest remaining time first is a preemptive version of the longest job first scheduling algorithm. This scheduling algorithm is used by the operating system to program incoming processes for use in a systematic way.  NETWORK TOPOLOGIES  NETWORK TOPOLOGIES Network topologies refer to the arrangement and layout of various elements (like nodes, links, and devices) in a computer network. They define how these components are interconnected and communicate with each other.Common types include bus, star, ring, mesh, and tree topologies.  Star Topology In a star topology, all nodes are connected to a central node, often a hub or a switch. The central node controls the network’s operation and facilitates communication between nodes.  Bus Topology Bus topology is one of the simplest forms of network topologies. It involves a single cable, termed the ‘bus’, which connects all network nodes. The data transmitted over the network travels in a single direction along the bus.  Mesh Topology Mesh topology is a type of network topology where each node is connected to every other node in the network. This creates multiple pathways for data transfer, which can enhance the network’s robustness and reliability.  Ring Topology Ring topology is a circular network configuration where each node is connected to two other nodes, forming a closed loop or ‘ring’. Data transmission occurs in one direction, from one node to the next, until it reaches the destination node.  Tree Topology This topology consists of a parent- child hierarchy in which star networks are interconnected via bus networks. Nodes branch out linearly from one root node, and two connected nodes only share one mutual connection.  Hybrid Topology Hybrid topology, as the name suggests, is a combination of two or more different types of network topologies. This flexibility allows for a highly customizable network that can meet a variety of specific requirements.  NETWORKING MODEL A networking model is a set of guidelines and standards that defines how data is transmitted and received over a network. It is also known as a networking architecture or a networking blueprint. It provides a common framework for network devices and software to communicate with each other.  OPEN SYSTEM INTERCONNECTION (OSI) The OSI (Open Systems Interconnection) Model describes how networked systems communicate. It is a theoretical framework for mapping how applications and devices link and send data over a web of connections. The OSI Model is called a “reference model” because it is rarely used in practical applications. 7 LAYERS & FUNCTION OF OSI MODEL  TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL MODEL The TCP/IP model defines how devices should transmit data between them and enables communication over networks and large distances. The model represents how data is exchanged and organized over networks. 4 LAYERS & FUNCTION OF TCP/IPMODEL KAMSAHAMMNIDA!!!