Regarding the subroutines, see the following sequence of tasks to be performed:
A. Turn on the interrupt facility.
B. Service the device whose flag is set.
C. Save the contents of processor registers.
D. Check which flag is set.
E. Restore the contents of processor registers.
🎥 Video solution / Text Solution of this question is given below:
Interrupt Service Routine (ISR) steps:
Save processor registers → C
Check which device raised interrupt → D
Service the device → B
Restore processor registers → E
Re-enable interrupt facility → A
Correct sequence:
C, D, B, E, A