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Unformatted text preview: Lecture 17: Interrupt tools Interrupts: 2 kinds- external and internal : external examples: Timers, keyboard, external drivers, serial and parallel ports, digital logic pulses. internal examples: (processor generated) illegal code exceptions, task scheduling algorithms. Generally, H/W interrupts are external and S/W interrupts are internal, but not always. Question: Clocks and Watchdogs are examples of which kinds of interrupt: internal/external? Software interrupts:-Not caused by a (asynchronous) hardware event, but by a specific (synchronous) machine language operation code, such as a debugger compiler trap or an unexpected software condition or error, such as a divide by zero, or an undefined instruction. -Defined in the CPU hardware and have entries in the interrupt vector so the hardware knows where to jump to execute the appropriate ISR (hence the O/S cannot stop it). Note: Linux O/S will accept multiple interrupt handlers on the same interrupt number. Hardware interrupts:-R/T OS and scheduling system have no control over their occurrence.-Vectored by the CPU H/W to the corresponding ISR just like the Software interrupts are....
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This note was uploaded on 04/07/2010 for the course ELEC ecse 421 taught by Professor Guss during the Winter '10 term at McGill.
- Winter '10