A certain microprocessor requires 4.5 microseconds to respond to an interrupt.…
2009
A certain microprocessor requires 4.5 microseconds to respond to an interrupt. Assuming that the three interrupts I1, I2 and I3 require the following execution time after the interrupt is recognized: i. I1 requires 25 microseconds ii. I2 requires 35 microseconds iii. I3 requires 20 microseconds I1 has the highest priority and I3 has the lowest. What is the possible range of time for I3 to be executed assuming that it may or may not occur simultaneously with other interrupts?
- A.
24.5 microseconds to 39.5 microseconds
- B.
24.5 microseconds to 93.5 microseconds
- C.
4.5 microseconds to 24.5 microseconds
- D.
29.5 microseconds 93.5 microseconds
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Correct answer: B
The minimum time for I3 is 24.5 microseconds, calculated as the response time plus execution time (4.5 + 20). The maximum time is 93.5 microseconds, which occurs if higher-priority interrupts I1 and I2 execute before I3: (4.5 + 25) + (4.5 + 35) + (4.5 + 20).
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