ch4.docx - Chapter 4 1 Hardware interrupts are asynchronous...

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Chapter 4 1. Hardware interrupts are asynchronous because they can occur at any time and any place while the code is running. Software interrupts are synchronous because they are generated by specific lines of code. 2. Interrupts allow the system to save power by entering a power save mode while waiting for the interrupt to occur, or the program can continue performing meaningful tasks for other parts of the system. Where as in polling the microprocessor must use standard power to wait and check for the interrupt condition to occur. 3. First an interrupt occurs, the program finishes current instruction. Then, the processor detects the interrupt, and pushes the PCR, and the SR are saved. Then, the PCR is loaded with memory location of the interrupt handler. Then, the program jumps the interrupt handler, where a context switch occurs (any registers used by the ISR are saved to the interrupt stack). Then, the processor searches though the devices in order of priority looking for the interrupting device.
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  • Spring '14
  • VerneW.Hansen
  • Interrupt, Interrupt handler, Programmable Interrupt Controller, hardware interrupts

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