The document discusses stack organization, a data structure that follows the Last-In-First-Out (LIFO) principle, detailing its operations (push and pop) and implementation methods (register and memory stacks). It describes how stack pointers work and outlines the procedural steps for the push and pop operations. Additionally, it explains the use of stacks in evaluating arithmetic expressions using Reverse Polish Notation (postfix notation).

1. STACK
ORGANISATION
Submitted by: Shivam Shrivastav
Roll no: 220150800054
Submitted to: MANDEEP SIR

2.  Stack: A storage device that stores
information in such a manner that the item
stored last is the first item retrieved.
 Stack is also called last-in first-out(LIFO).
it works on a LIFO principal.
STACK ORGANISATION

3. STACK ORGANISATION
Stack pointer: A register that holds the
address of the top item in the stack.
SP always points at the top item in the stack.
Stack Operations: The two operations are
 Push: It is used to insert an item into the stack.
 Pop: it is used to retrieve an item into the
stack.

4. IMPLEMENTATION OF STACK
In computer stack can be implemented
in two ways---
 Register stack
 Memory stack

5.  A stack is a collection of
registers storing temporary
information.
REGISTER STACK
A
FULL EMPTY
SP
B
C
DR
address
0
1
2
3
4
63
 In a 64-word stack, the stack
pointer contains 6 bits.
 The one-bit register is full is
set to 1 when the stack is
full.
 Empty register is 1 when the
stack is empty.
 The data registers(DR) hold
the data to be written into or
read from the stack.

6. STACK OPERATIONS
 PUSH OPERATIONS: The process of putting
a new element into the stack is known as
PUSH Operations.
• Step 1: Check if the stack is full.
• Step 2: If the stack is full, produce an error and
exit.
• Step 3: If the stack is not full, increment top to
point next space.
• Step 4: Add data element to stack location,
where the top is pointing.
• Step 5: Return success.
TOP
TOP
E

7. STACK OPERATIONS
 Pop Operations: Accessing the content while
removing it from the stack is known as a Pop
Operations
• Step 1:Checks if the stack is empty.
• Step 2:If the stack is empty, produce an error and
exit.
• Step 3:If the stack is not empty, access the data
elements at which the top is pointing.
• Step 4:Decreases the value of the top by 1.
• Step 5:Return success.
D
C
B
A
C
B
A
TOP
D

8. STACK OPERATIONS
REVERSE POLISH NOTATION(Postfix)
• A stack organization is very effective for evaluating arithmetic operations.
• A * B + C * D (AB*)+(CD*) = AB*CD*+
• (3 * 4 + 5 * 6 = (34*56*+)
• First convert the arithmetic expression into the equal to Polish
notation.
• PUSH the operands into the stack in the order in which they
appear.
• Finally only the results of the operation is left on the stack top.

9. STACK OPERATIONS
EVALUATING PROCEDURE:
• Scan the expression from left to right.
• When an operator is reached perform the operation with the
• operands found on the left side of the operator.
• Replace the two operands and the operator by the result
obtained from the operation.
(example)
Infix 3 * 4 + 5 * 6 = 42
Postfix 3 4 * 5 6 * +
12 5 6 * +
12 30 +
42

10. STACK OPERATION
REVERSE POLISH NOTATION
• Reverse polish notation evaluation with a stack.
• Stack is the most efficient way for evaluating arithmetic
operations.
Stack evaluation:
Get value
If the value is data: push the
data
Else if the value is operation:
Pop, pop evaluate and push

11. STACK OPERATION
REVERSE POLISH NOTATION
Example using stack to do this :
3 * 4 + 5 * 6 = 42
3 4 * 5 6 * +
SP
3
3
input
4
3
4
12
*
5
12
5
6
5
12
6
30
12
*
42
*

12. THANK YOU