Introduction to Operating SystemsAn Operating System?Computer System ComponentsAbstract View of System ComponentsFunction of Operating SystemSlide 6Parts of an Operating SystemEvolution (History) of OSSpoolingJob poolMultiprogrammingMultitasking (Time-sharing)Virtual MemoryKey Events 3rd GenerationKey Events (cont)Fourth Generation : (1980 – 1990)Key Events 4th GenerationKey Events 4th Generation (cont)5th Gen Parallel SystemsParallel Systems (Cont.)Real-Time SystemsDistributed SystemsDistributed Systems (Cont.)Why Operating Systems?01/14/19 CSE421, Spring 2001 1Introduction to Operating SystemsB. Ramamurthy(adapted from C. Egert’s and W. Stallings’ slides)An Operating System?What is an Operating System?A program that acts as an intermediary between a user of a computer and the computer hardware.What is the purpose of an operating system?To provide an environment in which a user can execute programs.What are the goals of an Operating System?The primary goal of an Operating System is to make the computer system convenient to use.The secondary goal is to make the computer system efficient to use.Computer System ComponentsHardware – provides basic computing resources (CPU, memory, I/O devices).Operating system – controls and coordinates the use of the hardware among the various application programs for the various users.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).Users (people, machines, other computers).Abstract View of System ComponentsFunction of Operating SystemOS as Extended machineComputer Architecture shows that computer is made up of chips and wiresWe do not want to program on the bare metalVirtual machine creates a hardware abstractionAbstract machine can provide hardware independent interfacesIncrease portabilityAllow greater protectionImplication is that it is much faster and easier to program with less errorsFunction of Operating SystemOS as resource managerCoordination and control of limited resources such as memory, disk, network, etcDeal with resource conflictsDeal with resource fairnessMake access efficient as possibleParts of an Operating SystemNo universal agreement on the topic, but most likelyMemory ManagementIO ManagementCPU SchedulingIPCMultiTasking/Multiprogramming(On some Operating System, this functionality is provided by a single program known as the kernel)What about?File SystemMultimedia SupportUI (X Windows, MSWin)Internet Browser?Why would extras be important01/14/19 CSE421, Spring 2001 8Evolution (History) of OSFirst Generation: Punched cardsSecond Generation: Transistors and batch systems.Third Generation: (Integrated Circuits)SpoolingMultiprogrammingMultitaskingVirtual MemorySpoolingStands for Simultaneous Peripheral Operation On-LineTakes advantage of disk technology (new at this point)Allows for overlap of IO from one job with the computation of another jobWhile executing current jobRead next job from card reader to diskPrint previous job to printerDisk is relegated to the role of a partitioned bufferJob poolAdvent of disk allows for random access (Tape and card are sequential)Several jobs can be waiting on the disk The job pool is a data structure that contains info and points to the jobs on the diskWe can now have job scheduling to determine the order in which the jobs run so that CPU utilization can increase.MultiprogrammingMemory partitioned into several piecesCPU Starts a jobIf the job is waiting for IO, the CPU can switch to another taskMultitasking (Time-sharing)Extension of MultiprogrammingNeed for user interactivityInstead of switching jobs when waiting for IO, a timer causes jobs to switchUser interacts with computer via CRT and keyboardSystems have to balance CPU utilization against response timeBetter device managementNeed for file system to allow user to access data and codeNeed to provide user with an “interaction environment”Virtual MemoryPrograms can be larger than memoryProgram loaded into memory as neededActive program and data “swapped” to a disk until neededMemory space treated uniformlyKey Events 3rd Generation1964-1966 IBM/360 and OS/3601964 Dartmouth Time Sharing System1965 DEC PDP-81965 MIT – Multics Time sharing System1969 – Beginnings of ARPANet1969 - Unix1971 IBM 4001 – Processor on a chip1973 – Ethernet concept Bob Metcalf @ Xerox Parc1974 - Gary Kildall – CP/M OS1974 Zilog Z80 ProcessorKey Events (cont)1974 - Edward Roberts, William Yates and Jim BybeeMITS Altair 8800. $375contained 256 bytes of memoryno keyboard, no display, and no aux storage device.1976 Steve Jobs and Steve WozniakApple II 1977 Commodore PET, Radio Shack TRS_801979 Unix 3BSDFourth Generation : (1980 – 1990)Personal ComputersComputer dedicated to a single userIO Devices now consist of keyboards, mice, CGA-VGA displays, small printersUser convenience and responsivenessCan adopt lessons from larger operating systemsNo need for some of the advanced options at the personal levelKey Events 4th Generation1981 IBM PC (8086)1981 Osborne 11981 Vic 201981 Xerox Star Workstation1984 Apple macintosh1984 SunOS1985 C++1985 MSWindows1986 – 386 ChipKey Events 4th Generation (cont)1987 OS/21988 Next Unix Workstations 1989 Motif1990 Windows 3, 1990 Berners-Lee Prototype for the web5th Gen Parallel SystemsMultiprocessor systems with more than one CPU in close communication.Tightly coupled system – processors share memory and a clock; communication usually takes place through the shared memory.Advantages of parallel system: Increased throughputEconomical Increased reliabilitygraceful degradationfail-soft systemsParallel Systems (Cont.)Symmetric multiprocessing (SMP)Each processor runs an identical copy of the operating system.Many processes can run at once without performance deterioration.Most modern operating systems support SMPAsymmetric multiprocessingEach processor is assigned a specific task; master processor schedules and allocates work to slave processors.More common in extremely large systemsReal-Time SystemsOften used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.Well-defined fixed-time constraints (known
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