A process is defined as a program in execution and is considered an active entity, contrasting with program code, which is passive. The document covers various aspects of processes, including their concepts, scheduling, memory structure, and the role of the operating system in managing processes. Additionally, it details how memory is organized for efficient functioning, explaining different memory sections such as text, data, heap, and stack.

1. 1

2. What is a Process?
 A process is a program in execution. Process is not as same as
program code but a lot more than it. A process is an 'active'
entity as opposed to program which is considered to be a
'passive' entity. Attributes held by process include hardware
state, memory, CPU etc .
2

3. Program & Process
 Program
- A computer program is a collection of instruction that performs a
specific task when executed by a computer .
- Passive entity
 Process
- Active entity
- Program code + pc + associated resources + Status of the
process’s execution . 3

4. Processes
• Process Concept
• Process Scheduling
• Operations on Processes
• Cooperating Processes
• Interprocess Communication
• Communication in Client-Server Systems
4

5. Process Concept
 An operating system executes a variety of programs: -
- Batch system – jobs
- Time-shared systems – user programs or tasks
 Process – a program in execution; process execution must progress in
sequential fashion.
 A process includes:
- Text section
- Data section
- Stack section
- program counter 5

6. Process Concept
• Program is passive entity stored on disk (executable file), process is active
– Program becomes process when executable file loaded into memory
• Execution of program started via GUI mouse clicks, command line entry of
its name, etc
• One program can be several processes
– Consider multiple users executing the same program
6

7. What the OS is going to do for the Process?
 Creating and removing( destroying )process .
 Controlling the progress of processes .
 Acting on interrupts and arithmetic errors .
 Resource allocation among processes .
 Inter process communication .
7

8. Process Memory
 Process memory is divided into four sections for efficient working : -
 The Text section is made up of the compiled program code, read in
from non-volatile storage when the program is launched.
 The Data section is made up the global and static variables,
allocated and initialized prior to executing the main.
 The Heap is used for the dynamic memory allocation, and is
managed via calls to new, delete, malloc, free, etc.
 The Stack is used for local variables. Space on the stack is reserved
for local variables when they are declared. 8

9. 9
#include<iostream>
using namespace std;
int total;
int Square(int x)
{
return x*x;
}
int SquareOfSum(int x,int y)
{
int z=Square(x+y);
return z;
}
int main()
{
int a=4,b=8;
total=SquareOfSum(a,b);
cout<<"Total ="<<total<<endl;
system("pause");
}
Process Memory
9

10. 10
#include<iostream>
using namespace std;
void main()
{
int x;
x=10;
int *ptr;
ptr=&x;
cout<<*ptr<<" "<<x<<" "<<ptr <<" "<<&x<<endl;
*ptr=30;
cout<<endl<<endl;
cout<<*ptr<<" "<<x<<" "<< ptr <<" "<<&x<<endl;
cout<<endl<<endl;
system("pause");
}
Stack & Heap

11. Any
Question ?
11

12. FOR
ATTENTIO
12