Module 1 - Part 1.pdf

Sudan University of Science and Technology College of Engineering Operating System Module 1 – Part 1 Introduction Dr. Isam Abdelnabi Osman...

Sudan University of Science and Technology College of Engineering Operating System Module 1 – Part 1 Introduction Dr. Isam Abdelnabi Osman Introduction What is an Operating System? Mainframe Systems Desktop Systems Multiprocessor Systems Distributed Systems Clustered System Real -Time Systems Handheld Systems Computing Environments Dr. Isam Abdelnabi Osman 2 1  What is an Operating System? A program that acts as an intermediary between a user of a computer and the computer hardware. Operating system goals: Execute user programs and make solving user problems easier. Make the computer system convenient to use. Use the computer hardware in an efficient manner. Dr. Isam Abdelnabi Osman 3 Computer System Components 1. Hardware – provides basic computing resources (CPU, memory, I/O devices). 2. Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. 3. Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs). 4. Users (people, machines, other computers). Dr. Isam Abdelnabi Osman 4 2  Abstract View of System Components 5 Dr. Isam Abdelnabi Osman Operating System Definitions Resource allocator Manages and allocates resources. Control program Controls the execution of user programs and operations of I/O devices. Kernel The one program running at all times (all else being application programs). Dr. Isam Abdelnabi Osman 6 3  Mainframe Systems Reduce setup time by batching similar jobs Automatic job sequencing – automatically transfers control from one job to another. First rudimentary operating system. Resident monitor initial control in monitor control transfers to job when job completes control transfers pack to monitor Dr. Isam Abdelnabi Osman 7 Memory Layout for a Simple Batch System 8 Dr. Isam Abdelnabi Osman 4  Multi-programmed Batch Systems Several jobs are kept in main memory at the same time, and the CPU is multiplexed among them. 9 Dr. Isam Abdelnabi Osman OS Features Needed for Multiprogramming I/O routine supplied by the system. Memory management – the system must allocate the memory to several jobs. CPU scheduling – the system must choose among several jobs ready to run. Allocation of devices. Dr. Isam Abdelnabi Osman 10 5  Time-Sharing Systems–Interactive Computing The CPU is multiplexed among several jobs that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory). A job swapped in and out of memory to the disk. On-line communication between the user and the system is provided; when the operating system finishes the execution of one command, it seeks the next “control statement” from the user’s keyboard. On-line system must be available for users to access data and code. Dr. Isam Abdelnabi Osman 11 Desktop Systems Personal computers – computer system dedicated to a single user. I/O devices – keyboards, mice, display screens, small printers. User convenience and responsiveness. Can adopt technology developed for larger operating system’ often individuals have sole use of computer and do not need advanced CPU utilization of protection features. May run several different types of operating systems (Windows, Mac OS, UNIX, Linux) Dr. Isam Abdelnabi Osman 12 6