On receiving an interrupt from a I/O device the CPU:a)Halts for a pred...
Answer should be D i.e branches off to ISR after completing current instruction.
CPU checks the status bit of interrupt at the completion of each current instruction running when there is a interrupt it service the interrupt using ISR.
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On receiving an interrupt from a I/O device the CPU:a)Halts for a pred...
Interrupt Handling in CPU
An interrupt is a signal that is sent to the CPU by an I/O device to request its attention. When the CPU receives an interrupt, it temporarily stops executing its current program and transfers control to a special routine called the interrupt service routine (ISR).
Handling Interrupts
When the CPU receives an interrupt, it follows the following steps to handle it:
1. Save the current state: The CPU saves the current state of the program, including the program counter, on the stack.
2. Determine the interrupt source: The CPU reads the interrupt request register to determine the source of the interrupt.
3. Disable interrupts: The CPU disables interrupts to prevent other interrupts from occurring while it is servicing the current interrupt.
4. Branch to the ISR: The CPU branches to the ISR, which is a special routine that handles the interrupt. The ISR executes a sequence of instructions to service the interrupt.
5. Enable interrupts: After the ISR completes, the CPU re-enables interrupts and returns to the interrupted program.
Option D
The correct answer is option D, i.e., the CPU branches off to the interrupt service routine after completion of the current instruction. This is because the CPU cannot immediately branch off to the ISR when it receives an interrupt. It must complete the current instruction before servicing the interrupt. This ensures that the program state is saved correctly before the CPU transfers control to the ISR.
Conclusion
In conclusion, interrupt handling is an important mechanism in the CPU that allows I/O devices to request the CPU's attention. When the CPU receives an interrupt, it temporarily stops executing its current program and transfers control to the ISR. The CPU follows a sequence of steps to handle the interrupt and returns to the interrupted program after the ISR completes.
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