S2 - computer system structures.ppt - Chapter 2 Computer-System Structures Computer System Operation I\/O Structure Storage Structure Storage Hierarchy

S2 - computer system structures.ppt - Chapter 2...

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Chapter 2: Computer-System StructuresComputer System OperationI/O Structure Storage StructureStorage HierarchyHardware ProtectionGeneral System Architecture
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Computer-System Architecturesystem busA general purpose computer-system consists of one or more CPUs and a number of device controllers that are connected through a common bus that provides access to a shared memory.Each device controller is in charge of specific type of device (for example, disk drives, audio devices or video displays).
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Computer-System OperationDevice controllers and the CPU can execute concurrently (in parallel), competing for memory.Memory controller synchronize access to the memory.Each device controller is responsibe from a particular device type.Each device controller has a local buffer.CPU moves data from main memory to local buffers or from local buffers to main memory.Input/Output is from the device to local bufferof device controller.Device controller informs CPU that it has finished its operation(i.e. read request) by causing an interrupt (a signal that shows occurrence of an event).
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Common Functions of InterruptsInterrupttransfers control to the appropriate interrupt service routine component of the device driver (responsible for dealing with the interrupt), through the interrupt vector, which contains the starting addresses of all the service routines for the various devices.Interrupt architecture must save the address of the interrupted instruction (the program counter).Incoming interrupts are disabledwhile another interrupt is being processed to prevent a lost interrupt, so any incoming interrupt is delayed until operating system is done with the current one; then, interrupts are enabled.A trapor exceptionis a software-generated interrupt caused either by an error in the program or a request from a user program.An operating system is managed by interrupts (interrupt driven).
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Common Functions of Interrupts (cont.)Interrupt driven (hardware and software)Hardware interrupt by one of the devices Software interrupt (exception or trap):Software error (e.g., division by zero)Invalid memory accessRequest for operating system service (using system calls)Other process problems include infinite loop, processes modifying each other or the operating system
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  • Fall '19
  • Interrupt, Computer data storage, Interrupt handler

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