Question

4. What is a stack in a microprocessor? What is the major different between a stack and a FIFO(First-In-First-Out)? Please explain the role of the stack pointer (SP).

Answer 1

STACK --

It is a LIFO (last in, first out) data structure implemented in the RAM area and is used to store addresses and data when the microprocessor branches to a subroutine. Then the return address used to get pushed on this stack. Also to swap values of two registers and register pairs we use the stack as well

DIFFERENCE BETWEEN STACK AND FIFO--

STACK

1. A stack is a linear data structure in which elements can be inserted and deleted only from one side of the list, called the top

2. A stack follows the LIFO (Last In First Out) principle, i.e., the element inserted at the last is the first element to come out

3. The insertion of an element into stack is called push operation, and deletion of an element from the stack is called pop operation

4. In stack we always keep track of the last element present in the list with a pointer called top.

FIFO

1. linear data structure in which elements can be inserted only from one side of the list called rear, and the elements can be deleted only from the other side called the front.

It is called a queue.

2. The queue data structure follows the FIFO (First In First Out) principle, i.e. the element inserted at first in the list, is the first element to be removed from the list.

3. In queue ( FIFO technique) we always maintain two pointers, one pointing to the element which was inserted at the first and still present in the list with the front pointer and the second pointer pointing to the element inserted at the last with the rear pointer

STACK POINTER --

A stack pointer is a small register that stores the address of the last program request in a stack. A stack is a specialized buffer which stores data from the top down.

Stack pointer holds the address of the last accupied memory location of the stack called stack pointer.

It is used to save the contents of register if it is required during the execution of a program.

It indicates which memory location onward the stack is vacent for further storage.

Any area of RAM can be used as stack.