1.4.3 How OS manages to run Applications?

Introduction

Application programs run on top of operating systems by utilizing the resources and services provided by the operating system. The operating system serves as an intermediary between the hardware and the application programs, managing tasks such as memory allocation, process scheduling, and device management.

Definition

Application Management is the function of the operating system that provides the necessary resources, services, and environment for application programs to run efficiently and safely.

Main Idea

When a user opens an application, the operating system performs several behind-the-scenes tasks to make it run. It allocates memory, schedules CPU time, manages input/output operations, and provides access to system resources like printers and network connections. The OS acts as a platform on which applications can run, providing a layer of abstraction that allows programs to interact with hardware without needing to know the specific details of the underlying hardware.

Core Concept

The operating system manages applications by:

• Allocating memory for the program to run
• Managing input/output operations such as reading and writing files
• Scheduling the program to run on the CPU
• Providing access to system resources such as printers and network connections
• Acting as an intermediary between hardware and application programs

Detailed Explanation

How the OS Runs an Application

For example, when a user opens a word processing program such as Microsoft Word, the operating system:

• Allocates memory for the program to run.
• Manages input/output operations such as reading and writing files.
• Schedules the program to run on the CPU.
• Provides access to system resources such as printers and network connections that the application program may need to use.

OS as a Platform

Overall, the operating system acts as a platform on which application programs can run, providing a layer of abstraction that allows programs to interact with the hardware without needing to know the specific details of the underlying hardware.

This means that a programmer does not need to know exactly which model of printer is connected or which type of hard drive is installed. The OS handles those details.

Intermediate Level

At the intermediate level, you should understand the specific roles the OS plays.

Memory Allocation: When you open an application, the OS finds free space in RAM and assigns it to the program. When you close the program, the OS frees that memory for other programs.

Process Scheduling: The OS decides when each program gets to use the CPU. If you have Word, Chrome, and a music player open, the OS switches between them so quickly that they all appear to run at the same time.

Device Management: If an application wants to print a document, it does not talk to the printer directly. It asks the OS, and the OS manages the printer queue and sends the data to the printer.

File Management: When an application saves a file, the OS decides where on the disk to store it and keeps track of its location.

Important Points

• - The OS is an intermediary between hardware and applications.
• - It allocates memory, schedules CPU time, and manages IO.
• - It provides access to resources like printers and networks.
• - It provides a layer of abstraction.
• - Applications do not need to know hardware details.
• - The OS ensures security between applications.

Remember

• - OS = intermediary between hardware and applications.
• - OS allocates memory.
• - OS schedules CPU time.
• - OS manages IO operations.
• - OS provides access to resources.
• - OS provides abstraction from hardware.
• - OS ensures security.

Common Mistakes

• - Thinking that applications talk directly to hardware (they talk through the OS).
• - Forgetting that the OS manages memory for each application.
• - Assuming that the OS only runs one application at a time (it can run many).
• - Thinking that the OS is not involved when an application prints or saves a file (it is heavily involved).
• - Confusing the role of the OS with the role of device drivers.

Quick Revision

• OS runs applications by allocating memory, scheduling CPU, managing IO, and providing resources.
• OS acts as a platform and intermediary.
• OS provides abstraction from hardware details.
• Applications request services from the OS.
• OS ensures security between applications.

60-Second Revision

• OS = intermediary between hardware and applications.
• OS allocates memory, schedules CPU, manages IO.
• OS provides access to printers, networks, files.
• OS provides abstraction from hardware.
• OS ensures security.
• Warning: Applications do not talk directly to hardware; they go through the OS.