Operating Systems Genesis, Development and Functions m.pptx

Genesis and development of operating system

1. Operating System Genesis, Development & Functions

2. Operating System P rogram that acts as an intermediary/interface between a user of a computer and the computer hardware It provides a user-friendly environment in which a user may easily develop and execute programs Otherwise , hardware knowledge would be mandatory for computer programming . So, it can be said that an OS hides the complexity of hardware from uninterested users .

3. Operating System Operating system goals: Execute programs and solve user problems easily Make the computer system convenient to use Use the computer hardware in an efficient manner Manage all hardware and software Controls every file, device, section of main memory and nanosecond of processing time Controls who can use the system Controls how system is used

4. When you turn on the computer, the CPU automatically begins executing instructions stored in ROM . The operating system (OS) loads from the disk into part of the system’s memory . OS loads the application program into memory and remains in memory , So that, it can provide services to the application program —display on-screen menus , communicate with printer and perform other common actions . Operating System

5. What Does an operating System Do? Every computer depends on an operating system to: Keep hardware running efficiently Maintains file system Support multitasking Manage virtual memory Operating system runs continuously when computer is on….

6. Functions of an Operating System Includes five essential subsystem managers Memory Manager Processor Manager Device Manager File Manager Network Manager

7. Main Memory Management In charge of main memory Random Access Memory (RAM) Responsibilities include: Preserving space in main memory occupied by operating system Checking validity and legality of memory space request Setting up memory tracking table Tracks usage of memory by sections Needed in multiuser environment De-allocating memory to reclaim it

8. Processor Management In charge of allocating (CPU) Tracks process status An instance of program execution Two levels of responsibility: Handle jobs as they enter the system Handled by Job Scheduler Manage each process within those jobs Handled by Process Scheduler

9. Device Management In charge of monitoring all resources Devices, channels, and control units Responsibilities include: Choosing most efficient resource allocation method Printers, ports, disk drives, etc. Based on scheduling policy Allocating the device Starting device operation Deallocating the device

10. File Management In charge of tracking every file in the system Data files, program files, compilers, application programs Responsibilities include: Enforcing user/program resource access restrictions Uses predetermined access policies Controlling user/program modification restrictions Read-only, read-write, create, delete Allocating resource Opening the file De-allocating file (by closing it)

11. Network Manager In all modern operating systems Assumes responsibility for networking tasks Convenient way for users to share resources Retains user access control Resources include: Hardware (CPUs, memory areas, printers, tape drives, modems, and disk drives) Software (compilers, application programs, and data files)

12. Functions of an Operating System Each manager: Works closely with other managers Performs a unique role Manager task Monitor its resources continuously Enforce policies determining: Who gets what, when, and how much Allocate the resource (when appropriate) De-allocate the resource (when appropriate)

13. Historical Development of an Operating System

14. Historical Development of OS Upto year 1955 Computers based on vacuum tube technology No standard operating system software Poor machine utilization From 1956- 1963 I/O device speed gradually became faster Records blocked before retrieval or storage Access methods developed Buffer between I/O and CPU introduced & Reduced speed discrepancy Timer interrupts developed Thus, Allowed job-sharing

15. Historical Development of OS Till 1970 Faster CPUs Speed caused problems with slower I/O devices Multiprogramming schemes used to reduce speed discrepancy with CPU Main memory physical capacity limitations Virtual memory developed to solve physical limitation Database management software was developed A number of query systems introduced Programs started using English-like words, modular structures, and standard operations

16. Historical Development of OS From 1971 to 1980 Cost/performance ratio of computer components More flexible hardware (firmware) Multiprocessing Allowed parallel program execution Evolution of personal computers Upto 1990 Demand for Internet capability Sparked production of networking capability Increased networking Tighter security demands to protect hardware and software Multimedia applications Demanding additional power, flexibility, and device compatibility for most operating systems

17. From 1990 till Present Primary design features support: Multimedia applications Internet and Web access Client/server computing Evolution of high-speed communications Distributed processing and networked systems introduced Computer systems requirements Increased CPU speed High-speed network attachments Increased number and variety of storage devices Virtualization Single server supports different operating systems

18. Evolution of computer Operating System

19. Evolution OF Operating System The evolution of operating systems went through seven major phases . Each of them significantly changed the ways in which users accessed computers through the open shop , batch processing , multiprogramming , timesharing , concurrent programming , personal computing , and distributed systems .

20. Evolution of Operating System Major Phases Technical Innovations Open Shop The idea of OS Batch Processing Tape batching, First-in, first-out scheduling. Multi-programming Processor multiplexing, Indivisible operations, Demand paging, Input/output spooling, Priority scheduling, Remote job entry Timesharing Simultaneous user interaction, On-line file systems Concurrent Programming Hierarchical systems, Extensible kernels, Parallel programming concepts, Secure parallel languages Personal Computing Graphic user interfaces Distributed Systems Remote servers

21. Operating Systems in different types of computers

22. Operating System Types Five categories Batch Interactive Real-time Hybrid Embedded Two distinguishing features Response time How data enters into the system

23. Batch Systems & Interactive Systems Batch Systems Input relied on punched cards or tape Efficiency measured in throughput Interactive Systems Faster turnaround than batch systems Slower than real-time systems Introduced to provide fast turnaround when debugging programs Time-sharing software developed for operating system

24. Real-time systems Reliability is key Fast and time limit sensitive Used in time-critical environments Space flights, airport traffic control, high-speed aircraft Industrial processes Distribution of electricity Telephone switching Must be 100% responsive, 100% of the time

25. Hybrid & Embedded systems Hybrid systems Combination of batch and interactive Accept and run batch programs in the background Interactive load is light Embedded systems Computers placed inside other products Adds features and capabilities Operating system requirements Perform specific set of programs Not interchangeable among systems Small kernel and flexible function capabilities