Details about stack in microprocessor

1. SUBMITTED BY
S.Nandhin
N.S COLLEGE OF ARTS & SCIENC

2. STACK INTRODUCTION
 What is stack ?
 Stack with example
 Push and Pop
 Difference Push and Pop
 Stack register

3. STACK
 The stack is a temporary store data and address
 The CPU may PUSH important data on to the stack
 While it is processing other data

4. What is Stack?
 The stack is a LIFO->LAST IN FIRST OUT
TOP
BOTTOM
5
4
3
2
1
STACK Pointer

5. STACK
 These are important instructions that store and retrieve
data the LIFO stack memory
 They Two main functions:
PUSH
POP
PUSH: Add item to top
POP: Remove item from top

6. STACK EXAMPLE
STACK IS
EMPTY
7
PUSH 7 PUSH 8
7
8

7. STACK Example
EMPTY
STACK
7
POP 8 POP 7

8. STACK INSTRUCTION
NAME
MNEMONICS AND
FORMAT DESCRIPTION
Push onto the stack PUSH SRC (SP) (SP)-2
((SP)+1: (sp))
(SRC)
Pop from the stack POP DST (DST) ((SP)+1:
(SP))
(SP) (SP)+2
Push the flags PUSHF (SP) (SP)-2
((SP)+1 : (SP))
(PSW)
Pop the flags POPF (PSW) ((SP)+1 :
(SP))
(SP) (SP)+2

9. PUSH & POP Definition
 These are important instruction that store and retrieve data the
LIFO Stack memory
 There are SIX Frames of the PUSH and POP
 Instruction,register,memory,immediate,segment register ,flags and all
register
 PUSH: Push op code copies data from the source address to stack.
 POP: Pop op code copies data from the stack to the destination address.

10. PUSH and POP example

11. Difference between PUSH &
POP Key Difference push is when an Entry is“PUSHED “ on to the Stack
 Pop is when the last pushed Entry is “Popped off” the stack
 PUSH & POP FOR EXAMPLE:
 PUSH CX
 PUSH DX
 POP DX
 POP CX

12. STACK REGISTER
o In 8086 main stack register is called Stack pointer (SP)
o The Stack segment register (SS) is usually used to store
information about memory segment
o That stores the call stack of currently Executed
program SP points to current Stack Top.

13. Setting up a Stack by Loading the SS and
Sp register
STACK_SEG EGMENT
DW 30 DUP(?)
TOS LABEL WORD
STACK_SEG ENDS
CODE_SEG SEGMENT
ASSUME CS:CODE SEG, SS:STACK SEG
START : MOV AX,STACK_SEG
MOV SS,AX ;INITIALIZES SS
MOV SP,OFFSET TOS ;INITIALIZES SP
:
:
CODE_SEG ENDS