VOSUnit
- 1. INTRODUCTION TO OPERATING SYSTEMS DEFINITION OF OPERATING SYSTEM: Operating System (OS) is a software that acts as an interface between computer hardware components and the user.
- 2. INTRODUCTION TO OPERATING SYSTEMS ROLE OF AN OPERATING SYSTEM 1. Memory Management 2. Processor Management 3. Device Management 4. File Management 5. Security 6. Control over system performance 7. Job accounting 8. Error detecting aids 9. Coordination between other software and users
- 3. INTRODUCTION TO OPERATING SYSTEMS Memory Management Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address. Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory.
- 4. INTRODUCTION TO OPERATING SYSTEMS Processor Management In multiprogramming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. Device Management An Operating System manages device communication via their respective drivers. It does the following activities for device management − Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.
- 5. INTRODUCTION TO OPERATING SYSTEMS File Management A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions.
- 6. INTRODUCTION TO OPERATING SYSTEMS Security By means of password and similar other techniques, it prevents unauthorized access to programs and data. Control over system performance Recording delays between request for a service and response from the system. Job accounting Keeping track of time and resources used by various jobs and users.
- 7. INTRODUCTION TO OPERATING SYSTEMS Error detecting aids Production of dumps, traces, error messages, and other debugging and error detecting aids. Coordination between other softwares and users Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.
- 8. INTRODUCTION TO OPERATING SYSTEMS TYPES OF OPERATING SYSTEM The Operating System is responsible for managing various resources of the system. 1. Batch Operating System 2. Time-Sharing Operating System 3. Distributed Operating System 4. Embedded Operating System 5. Real-time Operating System
- 9. INTRODUCTION TO OPERATING SYSTEMS Batch Operating System In a Batch Operating System, the similar jobs are grouped together into batches with the help of some operator and these batches are executed one by one. Time-Sharing Operating System In a Multi-tasking Operating System, more than one processes are being executed at a particular time with the help of the time-sharing concept. So, in the time-sharing environment, we decide a time that is called time quantum and when the process starts its execution then the execution continues for only that amount of time and after that, other processes will be given chance for that amount of time only.
- 10. INTRODUCTION TO OPERATING SYSTEMS Distributed Operating System In a Distributed Operating System, we have various systems and all these systems have their own CPU, main memory, secondary memory, and resources. These systems are connected to each other using a shared communication network. Here, each system can perform its task individually. Embedded Operating System An Embedded Operating System is designed to perform a specific task for a particular device which is not a computer.
- 11. INTRODUCTION TO OPERATING SYSTEMS Real-time Operating System The Real-time Operating Systems are used in the situation where we are dealing with some real-time data. So, as soon as the data comes, the execution of the process should be done and there should be no dealy i.e. no buffer delays should be there.
- 12. INTRODUCTION TO OPERATING SYSTEMS MAJOR OS COMPONENTS An operating system is a large and complex system that can only be created by partitioning into small pieces. These pieces should be a well-defined portion of the system, which carefully defined inputs, outputs, and functions.
- 13. INTRODUCTION TO OPERATING SYSTEMS Components: 1. File Management 2. Process Management 3. I/O Device Management 4. Network Management 5. Main Memory management 6. Secondary-Storage Management 7. Security Management 8. Other Important Activities
- 14. INTRODUCTION TO OPERATING SYSTEMS
- 15. INTRODUCTION TO OPERATING SYSTEMS File Management A file is a set of related information which is should define by its creator. It commonly represents programs, both source and object forms, and data. Data files can be numeric, alphabetic, or alphanumeric. Process Management The process management component is a procedure for managing the many processes that are running simultaneously on the operating system. Every software application program has one or more processes associated with them when they are running.
- 16. INTRODUCTION TO OPERATING SYSTEMS I/O Device Management One of the important use of an operating system that helps you to hide the variations of specific hardware devices from the user. Network Management Network management is the process of administering and managing computer networks. It includes performance management, fault analysis, provisioning of networks, and maintaining the quality of service.
- 17. INTRODUCTION TO OPERATING SYSTEMS Main Memory management Main Memory is a large array of storage or bytes, which has an address. The memory management process is conducted by using a sequence of reads or writes of specific memory addresses.
- 18. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS An operating system is a construct that allows the user application programs to interact with the system hardware. The major operations of the operating system are process management, memory management, device management and file management.
- 19. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS
- 20. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS Process Management The operating system is responsible for managing the processes i.e assigning the processor to a process at a time. This is known as process scheduling. The different algorithms used for process scheduling are FCFS (first come first served), SJF (shortest job first), priority scheduling, round robin scheduling etc.
- 21. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS Memory Management It deals with memory and the moving of processes from disk to primary memory for execution and back again.
- 22. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS Device Management There are many I/O devices handled by the operating system such as mouse, keyboard, disk drive etc. There are different device drivers that can be connected to the operating system to handle a specific device. The device controller is an interface between the device and the device driver.
- 23. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM OPERATIONS File Management Files are used to provide a uniform view of data storage by the operating system. All the files are mapped onto physical devices that are usually non volatile so data is safe in the case of system failure. Sequential Access Direct Access
- 24. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES An Operating System supplies different kinds of services to both the users and to the programs as well. It also provides application programs (that run within an Operating system) an environment to execute it freely. It provides users the services run various programs in a convenient manner.
- 25. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES An Operating System supplies different kinds of services to both the users and to the programs as well. It also provides application programs (that run within an Operating system) an environment to execute it freely. It provides users the services run various programs in a convenient manner.
- 26. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES common services offered by an almost all operating systems: User Interface Program Execution File system manipulation Input / Output Operations Communication Resource Allocation Error Detection Accounting Security and protection
- 27. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES User Interface Usually Operating system comes in three forms or types. Depending on the interface their types have been further subdivided. These are: Command line interface Batch based interface Graphical User Interface
- 28. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES Program Execution The operating system must have the capability to load a program into memory and execute that program. Furthermore, the program must be able to end its execution, either normally or abnormally / forcefully.
- 29. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES File System Manipulation Programs need has to be read and then write them as files and directories. File handling portion of operating system also allows users to create and delete files by specific name along with extension, search for a given file and / or list file information. Some programs comprise of permissions management for allowing or denying access to files or directories based on file ownership.
- 30. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM SERVICES Input/Output Operations A program which is currently executing may require I/O, which may involve file or other I/O device. For efficiency and protection, users cannot directly govern the I/O devices. So, the OS provide a means to do I/O Input / Output operation which means read or write operation with any file.
- 31. INTRODUCTION TO OPERATING SYSTEMS SYSTEM CALLS A system call is a method of interacting with the operating system via programs. A system call is a request from computer software to an operating system's kernel. A system call is a way for a user program to interface with the operating system.
- 32. INTRODUCTION TO OPERATING SYSTEMS Types of System Calls 1. Process Control 2. File Management 3. Device Management 4. Information Maintenance 5. Communication
- 33. INTRODUCTION TO OPERATING SYSTEMS Process Control Process control is the system call that is used to direct the processes. Some process control examples include creating, load, abort, end, execute, process, terminate the process, etc. File Management File management is a system call that is used to handle the files. Some file management examples include creating files, delete files, open, close, read, write, etc.
- 34. INTRODUCTION TO OPERATING SYSTEMS Device Management Device management is a system call that is used to deal with devices. Some examples of device management include read, device, write, get device attributes, release device, etc. Information Maintenance Information maintenance is a system call that is used to maintain information. There are some examples of information maintenance, including getting system data, set time or date, get time or date, set system data, etc.
- 35. INTRODUCTION TO OPERATING SYSTEMS Communication Communication is a system call that is used for communication. There are some examples of communication, including create, delete communication connections, send, receive messages, etc.
- 36. INTRODUCTION TO OPERATING SYSTEMS SYSTEM PROGRAMS System programs provide an environment where programs can be developed and executed. In the simplest sense, system programs also provide a bridge between the user interface and system calls.
- 37. INTRODUCTION TO OPERATING SYSTEMS Types of System Programs Status Information Communications File Manipulation Program Loading and Execution File Modification Application Programs
- 38. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Simple Structure Monolithic Approach Layered Approach Microkernels
- 39. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Simple Structure Operating systems such as MS-DOS and the original UNIX did not have well- defined structures. There was no CPU Execution Mode (user and kernel), and so errors in applications could cause the whole system to crash.
- 40. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Simple Structure
- 41. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Monolithic Approach Functionality of the OS is invoked with simple function calls within the kernel, which is one large program. Device drivers are loaded into the running kernel and become part of the kernel.
- 42. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Monolithic Approach
- 43. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Layered Approach This approach breaks up the operating system into different layers. This allows implementers to change the inner workings, and increases modularity. As long as the external interface of the routines don’t change, developers have more freedom to change the inner workings of the routines.
- 44. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Layered Approach
- 45. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Microkernels This structures the operating system by removing all nonessential portions of the kernel and implementing them as system and user level programs. Generally they provide minimal process and memory management, and a communications facility. Communication between components of the OS is provided by message passing.
- 46. INTRODUCTION TO OPERATING SYSTEMS OPERATING SYSTEM STRUCTURE Microkernels
- 47. INTRODUCTION TO OPERATING SYSTEMS PROCESS A process is a program at the time of execution. The process is more than the program code. It includes the program counter, the process stack, and the content of the process register, etc.
- 48. INTRODUCTION TO OPERATING SYSTEMS PROCESS Process States in OS 1. New: The process is being created. 2. Running: The process is being executed. 3. Waiting: The process is waiting for some event to occur. 4. Ready: The process is waiting to be assigned to a processor. 5. Terminate: The process has finished execution.
- 49. INTRODUCTION TO OPERATING SYSTEMS PROCESS SCHEDULING The process scheduling is the activity of the process manager that handles the removal of the running process from the CPU. Process scheduling is an essential part of a Multiprogramming operating systems. Such operating systems allow more than one process to be loaded into the executable memory at a time.
- 50. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES There are many operations that can be performed on processes. Some of these are process creation, process preemption, process blocking, and process termination.
- 51. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES Process Creation Processes need to be created in the system for different operations. This can be done by the following events. User request for process creation System initialization Execution of a process creation system call by a running process Batch job initialization
- 52. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES Process Creation
- 53. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES Process Preemption An interrupt mechanism is used in preemption that suspends the process executing currently and the next process to execute is determined by the short-term scheduler. Preemption makes sure that all processes get some CPU time for execution.
- 54. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES Process Blocking The process is blocked if it is waiting for some event to occur. This event may be I/O as the I/O events are executed in the main memory and don't require the processor. After the event is complete, the process again goes to the ready state.
- 55. INTRODUCTION TO OPERATING SYSTEMS OPERATIONS ON PROCESSES Process Termination After the process has completed the execution of its last instruction, it is terminated. The resources held by a process are released after it is terminated.
- 56. INTRODUCTION TO OPERATING SYSTEMS INTER PROCESS COMMUNICATION Interprocess communication is the mechanism provided by the operating system that allows processes to communicate with each other. This communication could involve a process letting another process know that some event has occurred or the transferring of data from one process to another.
- 57. INTRODUCTION TO OPERATING SYSTEMS Approaches for Inter-Process Communication