Operating System Concepts Lecture Slides PDF

Operating System Concepts Course Code: CSC Course Title: Operating Systems 2209 Dept. of Computer Science Faculty of Science and Technology Lecturer 01 Week Semest Fall 22-23 No: No:...

Operating System Concepts Course Code: CSC Course Title: Operating Systems 2209 Dept. of Computer Science Faculty of Science and Technology Lecturer 01 Week Semest Fall 22-23 No: No: er: Lecturer: Syma Kamal Chaity, [email protected] Lecture Outline 1. Computer System 2. Abstract View of Computer Components 3. What Operating Systems Do 4. Defining Operating Systems 5. Computer System Organization 6. Computer-System Operation 7. Interrupt 8. Computer Startup 9. Interrupt Handling 10. Interrupt-drive I/O Cycle Computer System  Computer system can be divided into four components:  Hardware – provides basic computing resources  CPU, memory, I/O devices  Operating system  Controls and coordinates use of hardware among various applications and users  Application programs – define the ways in which the system resources are used to solve the computing problems of the users  Word processors, compilers, web browsers, database systems, video games  Users  People, machines, other computers Abstract View of Computer Components What Operating Systems Do  Depends on the point of view  Users want convenience, ease of use and good performance  Don’t care about resource utilization  But shared computer such as mainframe or minicomputer must keep all users happy  Operating system is a resource allocator and control program making efficient use of Hardware and managing execution of user programs  Users of dedicate systems such as workstations have dedicated resources but frequently use shared resources from servers What Operating Systems Do (cont’d)  Mobile devices like smartphones and tables are resource poor, optimized for usability and battery life  Mobile user interfaces such as touch screens, voice recognition  Some computers have little or no user interface, such as embedded computers in devices and automobiles  Run primarily without user intervention Defining Operating Systems  Term OS covers many roles  Because of myriad designs and uses of OSes  Present in toasters through ships, spacecraft, game machines, TVs and industrial control systems  Born when fixed use computers for military became more general purpose and needed resource management and program control Operating System Definition (cont’d)  No universally accepted definition  “Everything a vendor ships when you order an operating system” is a good approximation  But varies wildly  “The one program running at all times on the computer” is the kernel, part of the operating system  Everything else is either  a system program (ships with the operating system, but not part of the kernel) , or  an application program, all programs not associated with the operating system  Today’s OSes for general purpose and mobile computing also include middleware – a set of software frameworks that provide addition services to application developers such as databases, multimedia, graphics Computer System Organization  Computer-system operation  One or more CPUs, device controllers connect through common bus providing access to shared memory  Concurrent execution of CPUs and devices competing for memory cycles Computer-System Operation  I/O devices and the CPU can execute concurrently  Each device controller is in charge of a particular device type  Each device controller has a local buffer  Each device controller type has an operating system device driver to manage it  CPU moves data from/to main memory to/from local buffers  I/O is from the device to local buffer of controller  Device controller informs CPU that it has finished its operation by causing an interrupt Common Functions of Interrupts  Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines  Interrupt architecture must save the address of the interrupted instruction  A trap or exception is a software-generated interrupt caused either by an error or a user request  An operating system is interrupt driven Interrupt Timeline Computer Startup  bootstrap program is loaded at power-up or reboot  Typically stored in ROM or EPROM, generally known as firmware  Initializes all aspects of system  Loads operating system kernel and starts execution Interrupt-driven I/O Cycle Books  Operating Systems Concept  Written by Galvin and Silberschatz  Edition: 9th References  Operating Systems Concept  Written by Galvin and Silberschatz  Edition: 9th