Polling
Repeated checking of device status instead of using interrupts. Polling is simpler but less efficient than interrupts. Suitable for infrequent events.
Real World
Early USB 1.0 mice used polling where the CPU checked the mouse port roughly 125 times per second, wasting processor cycles — modern USB mice use interrupt-driven transfers instead.
Exam Focus
When comparing polling and interrupts, explicitly state polling wastes CPU cycles while interrupts free the processor.
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