Interrupt -Gate 2001- Previous year solved gate questions for cse.
Interrupt -Gate 2001- Previous year solved gate questions for cse.
Certainly! Let’s delve into the GATE CSE 2001 questions related to interrupts, providing detailed explanations for each.
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Question 1: Purpose of Software Interrupts
Question:
A processor needs a software interrupt to:
Options:
A. Test the interrupt system of the processor
B. Implement co-routines
C. Obtain system services which need execution of privileged instructions
D. Return from subroutine
Correct Answer: C. Obtain system services which need execution of privileged instructions
Explanation:
Software interrupts, often invoked via system calls, allow user-level applications to request services from the operating system. These services typically require execution in a privileged mode to access hardware or critical system resources. By triggering a software interrupt, control is transferred to the OS, which can safely execute the necessary privileged instructions on behalf of the application.
Question 2: Mode Transition in CPU
Question:
A CPU has two modes—privileged and non-privileged. In order to change the mode from privileged to non-privileged:
Options:
A. A hardware interrupt is needed
B. A software interrupt is needed
C. A privileged instruction (which does not generate an interrupt) is needed
D. A non-privileged instruction (which does not generate an interrupt) is needed
Correct Answer: C. A privileged instruction (which does not generate an interrupt) is needed
Explanation:
Transitioning from privileged to non-privileged mode is typically executed by the operating system after completing a system-level task. This transition is achieved through a privileged instruction that sets the processor’s mode bit accordingly. Unlike transitions from non-privileged to privileged mode, which require an interrupt (e.g., system call), this operation doesn’t generate an interrupt.
Question 3: Interrupting a Running Process
Question:
Which of the following does not interrupt a running process?
Options:
A. A device
B. Timer
C. Scheduler process
D. Power failure
Correct Answer: C. Scheduler process
Explanation:
The scheduler is a component of the operating system responsible for managing process execution. It decides which process runs at a given time but doesn’t inherently interrupt processes. Interrupts are typically generated by hardware events (like devices or timers) or critical failures (like power loss). Therefore, the scheduler itself doesn’t cause interrupts; it responds to them.
For a comprehensive understanding and further practice, you might find this video explanation helpful:
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