Question

On receiving an interrupt from an I/O device, the CPU:
1. Halts for a predetermined time
2. Branches off to the interrupt services routine after completion of the current instruction
3. Branches off to the interrupt service routine immediately
4. Hands over control of address bus and data bus to the interrupting device

Answer 1

Correct Answer - Option 2 : Branches off to the interrupt services routine after completion of the current instruction

Concept:

When CPU executing the same task & meanwhile it receives an interrupt then,

I) First it will finish the current task

II) After completion of current instruction it will branches off to the interrupt service routine.

ISR:

It stands for Interrupt service routine or also known as an interrupt handler.

It is a software process invoked by an interrupt request from a hardware device.

It handles the request and sends it to the CPU i.e. interrupting the active process. When the ISR is complete, the process is resumed.