Operating System: Definition, Functions, and Generations of Computers

2. Chapter Test 1 Marks: 20 Define batch, hard real time system, degree of multiprogramming , background job, quantum Draw diagram of OS, Batch OS, Distributed OS Explain generations of computer Define OS and list out any 8 services BEST OFLUCK

3. SSS Foundation CourseOperating System(17512) PPT Created and Developed by: Prof. Suyog S. Dhoot Lecturer (Information Technology), K. K.Wagh Polytechnic, Nashik Mobile No: 9762424330 Email id: sdhoots@gmail.com Website: sssdhootkkwp.wordpress.com Prof. Suyog S.Dhoot

4. Syllabus

5. Objectives Definition of OS Functions of OS Generations of OS Evolution of OS Types of OS

6. Operating system

7. Operating system An operating system act as an intermediary between the user of a computer and computer hardware. The purpose of an operating system is to provide an environment in which a user can execute programs in a convenient and efficient manner. An operating system is a software that manages the computer hardware. An Operating system is concerned with the allocation of resources and services, such as memory, processors, devices and information.

8. Functions of os Execution of program Memory Management Processor Management File Management Device Management Job Accounting Security Error Detection Control over system performance

9. Functions of os Job Accounting : Time and Resources use by jobs and users Security : Providing unauthorized access to data Error Detection : Error message and debugging Control over system performance : Delay between request of service and response from system Device Management : i/o controller Processor Management: traffic controller

10. GENERATIONS OF COMPUTER/ EVOLUTION of os

11. GENERATIONS OF COMPUTER 1st generation 1940-1955 Main electronic component is vacuum tube Used machine level language Punch card used as input device Speed milliseconds ENIAC: Electronic Numerical Integrator and Calculator 30*50 feet long, 18000 tube, 30 ton weight

12. GENERATIONS OF COMPUTER 2nd generation 1955-1965 Main electronic component is transistor Used assembly level language Punch card used as input device Speed microseconds Less heat, FORTAN and COBOL used IBM 1401, IBM 1620

13. GENERATIONS OF COMPUTER 3rd generation 1965-1975 Main electronic component is Integrated Circuit Used assembly level language Keyboard and Mouse used as input device Speed Nano seconds IBM 360, IBM 370

14. GENERATIONS OF COMPUTER 4th generation 1975-1990 Main electronic component is Microprocessor Networking, GUI Keyboard and Mouse used as input device Apple, IBM PC

15. GENERATIONS OF COMPUTER 5th generation 1990 Artificial intelligence Expert system Nano technology

16. Batch OS Program and Input data is called job where as group of similar job called as batch. Executing jobs in batch , reduce setup operation to once and multiple programs can be executed with same setup User do not intereact with computer directly. It will submit job to software which reside in memory called as monitor. Functions of monitor: Accepting jobs from user Set up for first job At end of job, terminate process and transfer to next job At end of batch, terminate batch and transfer to new batch

17. Batch OS Advantages: Setup time reduced Performance increased Useful for billing, Banking applications Disadvantages: Lack of interaction between user and job Difficult to provide security and priority CPU time not properly utilized

18. Real Time System a system must produce output for given input within specific given amount of time Real time systems are usually dedicated embedded systems. They typically read from and react to sensor data. The system must guarantee response to events within fixed periods of time to ensure correct performance. Types: Hard: Response time is absolute value and task must finish within deadline. Soft: Response time is average and task may finish within deadline or it may take more time.

19. Real Time System Applications: Medical Applications Robotics and Automation Web based applications Virtual Reality Direct interaction between user and application Can lead to faults and security

20. Multiprogrammed os In this multiple number of programs simultaneously but one at a time. User interaction is not possible To reduce uniprogramming drawback an attempt was made to keep cpu busy for all time Numbers of programs executing simultaneously is called as degree of multiprogramming

21. Multiprogrammed os Advantages: Throughput increased Response time is good Performance of CPU increase Disadvantages: Memory management required Maintenance required and tracking of jobs required

22. multitasking In this more than one program or task get executed at same time or simultaneously User interaction is possible a task may be to watch movie, print document, compile program etc. It execute one job in foreground and many job in background Foreground job requires human interaction while background jobs not required interaction E.g. editing of document file along with printing of another document file Not reliable, not secure but cpu, i/o utilization is good

23. multiprocessor It use two or more CPU within single computer system. All cpu shares system bus, memory and other resources Maximum work done in shorter period Data in memory share by multiple processor instead of making copies Cpu communicate with each other as one cpu fails , system does not halt or fail Symmetric : Same Processor share memory Asymmetric: Different processor not share memory

24. multiprocessor OS Advantages: Throughput increased Reliability increased Hardware cost reduced Disadvantages: Complex in design Expensive as use of cpu os must support that processor

25. Distributed os In this number of computers connected to each other using cables for sharing and communication data among each other. Different applications, process or program avaliable on different system. It use to overcome centralized OS concept Applications: Student Information system rain Reservation system Types: Vertical: Various levels of functionality and send information to high level Horizontal: All computer system at same level

26. Distributed OS Advantages: Throughput increased Reliability increased Hardware cost reduced Disadvantages: Complex in design networking required

27. Time share OS A time sharing system allows many users to share the computer resources simultaneously. Time sharing refers to the allocation of computer resources in time slots to several programs simultaneously. Equal time slots are provided to user for execution of programs which also leads to the context switching, in which process shifts control from one to another In case any process does not complete its working within time slot then extra time slot will not be given to it. For example- you are running a process with a time slot of 5 seconds and in case process does not complete in 5 second and requires 1 extra second then it will be executed in next execution cycle but time slot will not be extended. short period of time during that a user gets attention of the CPU is known as a time slice or a quantum

28. Services of os Program Execution I/O operation File Manipulation Error detection Communication Resource allocation Accounting Protection/ Security

29. Services of os Program Execution OS provide facility to user to create program then it loads in memory and finally get executed. After successful execution, program get terminated successfully After unsuccessful execution , program terminated abnormally by indicating errors I/O operation It provide facility to perform input/output operation with hardware or different process. e. g read or write data on I/O device.

30. Services of os File Manipulation Program needs to read a file or write a file. The operating system gives the permission to the program for operation on file. Permission varies from read-only, read-write, denied and so on. Operating System provides an interface to the user to create/delete files/directories. Operating System provides an interface to create the backup of file system.

31. Services of os Error Detection An error is one part of the system may cause malfunctioning of the complete system. To avoid such a situation the operating system constantly monitors the system for detecting the errors. Errors may occur in CPU, Memory, I/O devices or programs For each type of error, OS must take corrective step to recover from that.

32. Services of os Communication exchange of information between processes executing either on the same computer or on different syste.ms tied together by a network. Implemented via shared memory or message passing. Specific hardware or user program used for this. Protection Protection refers to mechanism or a way to control the access of programs, processes, or users to the resources defined by a computer systems. OS ensures that external I/O devices are protected from invalid access attempts. OS provides authentication feature for each user by means of a password.

33. Services of os Resource Allocation Allocating resources to multiple users or multiple jobs running at the same time. Resource may be hardware – CPU, Memory, I/O Device or software- Programs It must handle situation in such manner that all user get resources whenever they demand Accounting keep track of and record which users use how much and what kinds of compute resources for account billing. It can be use to detect error or to add some resources or for protection purpose.

34. System component activities OS breaks into modules or parts which perform specific task Process Management Memory Management File Management I/O System Management Secondary Storage Management Networking Managment

35. System component activities Process Management Process: Program in Execution state Activities involve in handling process called process management Process is active entity which require resources for execution Activities: Creation of user and system process Suspending and resuming process Mechanism for process communication, synchronization, deadlock handling

36. System component activities Main Memory Management RAM is main memory present in CPU Activities involve in handling memory called memory management Memory management require for smooth functioning of System Activities: Tracking of memory Deciding priority to allocate memory Allocation and DEallocation of memory

37. System component activities File Management File: Collection of programs and data Activities involve in handling Files called File management Directory: Collection of Files Activities: Creation, deletion, updation of files and directories Backup to secondary storage File Manipulation

38. System component activities I/O System Management It includes Hardware Activities involve in handling I/O device called I/O device management Drivers required to operate I/O device Activities: Performing Buffering, Caching and Spooling Memory management to devices Effective utilization Driver Support and hiding complexity of hardware

39. System component activities Networking Management Computers are connected to each other for sharing information is called network Activities involve in networking called networking management Protocol used Activities: Mechanism to share data or resource Mechanism to connect computers to each other Providing security and permissions Mechanism to detect fault

40. System component activities Secondary Storage Management It includes CD, DVD, Flopy, PenDrive, HardDisk Activities involve in handling device called management Security mechanism required Activities:

41. System call The mechanism used by an application program to request service from the operating system System call available in assembly level or high level language System call are access using API users do not need to write their own environment for program development (editors, compilers) and program execution .

42. Types System call System calls for Process or Job control File Manipulation Device management Information management Communication

43. Types System call Process or Job control End Abort Load Execute Create Terminate Suspend Resume Get and Set process attributes: id, state, priority Wait for time, Event Change the priority of process

44. Types System call File manipulation Create File Delete File Open File Close Read Write Reposition Get File Attributes Set File Attributes

45. Types System call Device Management Request device Release device Read Write Reposition Get and Set device attributes: id, name, type, speed

46. Types System call Information Management Get Time Set Time Get system data Set system data Get and Set Process, File or Device attributes

47. Types System call Communication Create connection Delete connection Send message Receive message Transfer status information Logically attach and detach remote device

48. Process state Different process states are New Newly created process Memory is not available so not ready for execution Once called in life time Ready Process ready for execution waiting for cpu time After getting cpu time it start execution Running Process which hold cpu time and start execution In this program becomes process

49. Process state Different process states are Blocked Process stop execution due to unavailability of I/O device or event Memory space occupied by process is released After block state it goes to ready state Terminated / Halted After successful completion of process it enters into terminated state Unsuccessful completion also turns into terminated state by indicating errors After getting cpu time it start execution

50. Process state