PUSH and POP are instructions used in microprocessors/controllers to save and retrieve data from the stack. The stack is a temporary storage area in the memory that is used for storing data and return addresses during the execution of a program.
When PUSH instruction is executed, it stores the data onto the top of the stack by decrementing the stack pointer. When POP instruction is executed, it retrieves the data from the top of the stack by incrementing the stack pointer.
The main purpose of PUSH and POP instructions is to save and retrieve data in the stack. This is useful in managing the execution of a program by allowing the processor to temporarily store and retrieve data without having to access the main memory.
The main difference between PUSH and POP is that PUSH stores data onto the stack, while POP retrieves data from the stack. Additionally, PUSH decrements the stack pointer, while POP increments it. Also, PUSH can take multiple data values as input, while POP can only retrieve one data value at a time.
PUSH and POP instructions are commonly used in programming to manage the execution of subroutines or functions. When a subroutine is called, the return address is pushed onto the stack, and when the subroutine is finished, the return address is popped from the stack to continue the execution of the main program. They are also used for passing parameters and local variables between different parts of a program.