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Intro 1 What is an Operating System? ¯ Three views of an operating system Application View: what services does it provide? System View: what problems does it solve? Implementation View: how is it built? An operating system is part cop, part facilitator. CS350 Operating Systems Fall 2005 Intro 2 Application View of an Operating System ¯ The OS provides an execution environment for running programs. – The execution environment provides a program with the processor time and memory space that it needs to run. – The execution environment provides interfaces through which a program can use networks, storage, I/O devices, and other system hardware components. £ Interfaces provide a simplified, abstract view of hardware to application programs. – The execution environment isolates running programs from one another and prevents undesirable interactions among them. CS350 Operating Systems Fall 2005 Intro 31 Other What Views is anofOperating an Operating System? System System View: The OS manages the hardware resources of a computer system. ¯ Resources include processors, memory, disks and other storage devices, network I/O devices ¯ Three viewsinterfaces, of an operating systemsuch as keyboards, mice and monitors, and so on. View: what services does it provide? Application ¯ The operating system allocates System View: what problems doesresources it solve? among running programs. It controls the sharing of resources among programs. Implementation View: how is it built? ¯ The OS itself also uses resources, which it must share with application programs. Implementation View: The OS is a concurrent, real-time program. An operating system is part cop, part facilitator. ¯ Concurrency arises naturally in an OS when it supports concurrent applications, and because it must interact directly with the hardware. ¯ Hardware interactions also impose timing constraints. CS350 Operating Systems Fall 2005 Intro 42 Application Schematic View Viewof ofan anOperating OperatingSystem System User Programs ¯ The OS provides an execution environment for running programs. system call system calls – The execution environment provides a program results with the processor time and memory space that it needs to run. system call interface – The execution environment provides interfaces through which a program can use networks, storage, I/O devices, and other system hardware Operating System components. £ Interfaces provide a simplified, abstract view of hardware to application programs. commands data and interrupts and data – The execution environment isolates running programs from one another and prevents undesirable interactions among them. Resources CS350 Operating Systems Fall 2005 Intro 531 Other Operating What Views is anof System Operating an Operating Abstractions System? System System View: The OS manages the hardware resources of a computer system. ¯ The execution environment provided by the OS includes a variety of abstract ¯ Resources include processors, memory, disks and other storage devices, entities that can be manipulated by a running program. Examples: network I/O devices ¯ Three viewsinterfaces, of an operating systemsuch as keyboards, mice and monitors, and filessoand systems: abstract view of secondary storage on.file View: Application what services does it provide? address spaces: abstract view of primary memory ¯ The operating system allocates System View: what problems doesresources it solve? among running programs. It processes, abstract view ofamong program execution controlsthreads: the sharing of resources programs. Implementation View: how is it built? sockets, pipes: view of network or it other channels ¯ The OS itselfabstract also uses resources, which mustmessage share with application programs. ¯ This course will cover Implementation The OS a concurrent, real-time program. – why theseView: abstractions areisdesigned the way they are An operating system is part cop, part facilitator. arises naturally in an OS when it supportsprograms concurrent –¯ Concurrency how these abstractions are manipulated by application applications, and because it must interact directly with the hardware. – how these abstractions are implemented by the OS ¯ Hardware interactions also impose timing constraints. CS350 Operating Systems Fall 2005 Intro 642 Application Schematic View View Course of ofan an Outline Operating OperatingSystem System User Programs ¯ Introduction ¯ The OS provides an execution environment for running programs. ¯ Processes and Threads system call system calls – The execution environment provides a program results with the processor time ¯ Concurrency andspace Synchronization and memory that it needs to run. system call interface – The execution environment provides interfaces through which a program ¯ Address Spaces and Virtual Memory can use networks, storage, I/O devices, and other system hardware ¯ Scheduling Operating System components. ¯ Devices and Device Management £ Interfaces provide a simplified, abstract view of hardware to application programs. commands ¯ File Systems data and interrupts and data – The execution environment isolates running programs from one another ¯ Interprocess Communication and Networking and prevents undesirable interactions among them. ¯ Security Resources CS350 Operating Systems Fall 2005 Intro 531 Other Operating What Views is anof System Operating an Operating Abstractions System? System System View: The OS manages the hardware resources of a computer system. ¯ The execution environment provided by the OS includes a variety of abstract ¯ Resources include processors, memory, disks and other storage devices, entities that can be manipulated by a running program. Examples: network I/O devices ¯ Three viewsinterfaces, of an operating systemsuch as keyboards, mice and monitors, and filessoand systems: abstract view of secondary storage on.file View: Application what services does it provide? address spaces: abstract view of primary memory ¯ The operating system allocates System View: what problems doesresources it solve? among running programs. It processes, abstract view ofamong program execution controlsthreads: the sharing of resources programs. Implementation View: how is it built? sockets, pipes: view of network or it other channels ¯ The OS itselfabstract also uses resources, which mustmessage share with application programs. ¯ This course will cover Implementation The OS a concurrent, real-time program. – why theseView: abstractions areisdesigned the way they are An operating system is part cop, part facilitator. arises naturally in an OS when it supportsprograms concurrent –¯ Concurrency how these abstractions are manipulated by application applications, and because it must interact directly with the hardware. – how these abstractions are implemented by the OS ¯ Hardware interactions also impose timing constraints. CS350 Operating Systems Fall 2005 Intro 642 Application Schematic View View Course of ofan an Outline Operating OperatingSystem System User Programs ¯ Introduction ¯ The OS provides an execution environment for running programs. ¯ Processes and Threads system call system calls – The execution environment provides a program results with the processor time ¯ Concurrency andspace Synchronization and memory that it needs to run. system call interface – The execution environment provides interfaces through which a program ¯ Address Spaces and Virtual Memory can use networks, storage, I/O devices, and other system hardware ¯ Scheduling Operating System components. ¯ Devices and Device Management £ Interfaces provide a simplified, abstract view of hardware to application programs. commands ¯ File Systems data and interrupts and data – The execution environment isolates running programs from one another ¯ Interprocess Communication and Networking and prevents undesirable interactions among them. ¯ Security Resources CS350 Operating Systems Fall 2005