GATE CSE 2018 · Q9

MCQ1 markEasy

Time00:00

The following are some events that occur after a device controller issues an interrupt while process $L$ is under execution. (P) The processor pushes the process status of $L$ onto the control stack. (Q) The processor finishes the execution of the current instruction. (R) The processor executes the interrupt service routine. (S) The processor pops the process status of $L$ from the control stack. (T) The processor loads the new PC value based on the interrupt.

Which one of the following is the correct order in which the events above occur?

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Solution

Step-by-step verified solution

Official answer: A) QPTRS

I/O Interface, Interrupts and DMA

When an interrupt occurs during the execution of process $L$ , the CPU handles it in the following sequence:

(Q) The processor completes the execution of the currently running instruction before switching contexts.
(P) The processor saves the context (process status/registers/return PC) of $L$ by pushing it onto the control stack.
(T) The processor loads the program counter (PC) with the starting address (vector) of the interrupt handler.
(R) The processor executes the Interrupt Service Routine (ISR).
(S) After servicing the interrupt, the processor pops the saved status of $L$ from the control stack and resumes execution of process $L$ .

Thus, the correct order is QPTRS, which corresponds to option (A).

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This I/O Interface, Interrupts and DMA previous year question is Q9 of the GATE CSE 2018 paper. Find more GATE CSE PYQs on I/O Interface, Interrupts and DMA in Computer Organization and Architecture, or browse all GATE CSE PYQs.

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I/O Interface, Interrupts and DMA in GATE CSE

I/O Interface, Interrupts and DMA has 13 GATE CSE PYQs across 12 papers from 2011 to 2026. 8 of them are 1-mark MCQs like this one, and it is the only one in GATE CSE 2018.

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.