Topic: Microprocessors and Microcontrollers
Correct order of execution of action taken by 8051 micro-controllers when an interrupt occurs:
- A. C, A, D, E, B
- B. A, B, D, E, C
- C. C, D, B, E, A
- D. A, C, B, D, E
Answer: A. C, A, D, E, B
Explanation: When an interrupt occurs, the 8051 sequentially processes it by first completing the execution of the current instruction (C). It then saves the Program Counter (PC) by pushing it to the stack (A), followed by clearing the interrupt flag if it is hardware-cleared (D), setting the internal interrupt-in-progress flag (E), and finally generating a long call (LCALL) to the Interrupt Service Routine vector (B).