We can simplify this code somewhat by dening the

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Unformatted text preview: rrent instruction Never returns Figure 8.4: Classes of exceptions. Asynchronous exceptions occur as a result of events external to the processor. Synchronous exceptions occur as a direct result of executing an instruction. Interrupts Interrupts occur asynchronously as a result of signals from I/O devices that are external to the processor. Hardware interrupts are asynchronous in the sense that they are not caused by the execution of any particular instruction. Exception handlers for hardware interrupts are often called interrupt handlers. 8.1. EXCEPTIONS 395 Figure 8.5 summarizes the processing for an interrupt. I/O devices such as network adapters, disk controllers, and timer chips trigger interrupts by signalling a pin on the processor chip and placing the exception number on the system bus that identifies the device that caused the interrupt. (1) interrupt pin goes high during I curr execution of Inext current instruction (2) control passes to handler after current instruction finishes (3) interrupt handle...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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