Question

The step involved in PUSH operation is

(a) increment stack by 2 and store 8-bit content to address pointed to by SP

(b) decrement stack by 1 and store 16-bit content to address pointed to by SP

(c) increment stack by 1 and store 8-bit content to address pointed to by SP

(d) store 8-bit content to address pointed to by SP and then increment stack by 1

This question was posed to me in an international level competition.

The query is from Interrupt and Stack of 8051 in chapter Microcontroller 8051 of Microprocessor

Answer 1

The correct answer is (c) increment stack by 1 and store 8-bit content to address pointed to by SP

The explanation is: The PUSH instruction follows two steps.

1. Increment stack by 1

2. Store 8-bit content of the 8-bit address specified in the instruction to the address pointed to by SP.