Suppose a program is running on a non-pipelined single processor computer system. The computer is connected to an external device that can interrupt the processor asynchronously. The processor needs to execute the interrupt service routine (ISR) to serve this interrupt. The following steps (not necessarily in order) are taken by the processor when the interrupt arrives:
(i) The processor saves the content of the program counter.
(ii) The program counter is loaded with the start address of the ISR.
(iii) The processor finishes the present instruction.
Which ONE of the following is the CORRECT sequence of steps?
(iii), (i), (ii)
(i), (iii), (ii)
(i), (ii), (iii)
(iii), (ii), (i)
The following steps are executed, when the system received an interrupt from ISR
Step No:
• Finishes the current executing instruction
• CPU pushes the PC content on stack
• The PC is updated with the new ISR address
Hence correct Answer : (A)