Understanding the Structure of an Operating System

The most important and complicated piece of software is the operating system (OS), which is in charge of managing computer hardware and software resources. In other words, it is a program that enables software to communicate with a device’s hardware components. But have you ever wondered how the operating system is organized and how its parts work together to manage memory, store files, manage devices, and run background programs? We will attempt to acquire a solid understanding of the OS’s system structure and types in this blog. So, without any further ado, let’s get started.

What is Operating System Structure

The configuration of how various OS components, such as the Kernel, System Calls, Process Scheduler, I/O Subsystem, Security Manager, and User Interface Layer, are organized and linked to one another is referred to as the OS’s structure. When a specific OS is structured effectively with all required settings, overall system performance and reliability increase significantly, and it becomes easier to maintain and manage those systems. The OS’s functionality is used to organize many of its components.

Importance of System Structuring in OS

Well-structured OS enhances the system performance.
By separating internal program components, it makes maintenance easier and increases security. Ensures seamless communication between hardware and software systems.
During operational scenarios, it provides stability and consistency to the OS.
For users, it becomes simpler to maintain, upgrade the OS, and troubleshoot issues.

Types of Structures in Operating Systems (OS)

The following is a list of the various operating system structures, each of which has its own working mechanism and characteristics that indicate how effectively it manages system resources and operations:

1. Simple Structure

An operating system (OS) with a simple structure is a collection of processes that combine various software services into a single module. For better comprehension, there is no layered architecture involved while arranging the components. In order to avoid system outages and failures, various software blocks like file management, device drivers, memory management, and process management are directly connected here. (Working Mechanism)

When the computer system boots, the OS module is loaded first and initializes devices and memory tables. Once initialization is complete, a user program is executed in the background, which triggers the system call.

After the central processing unit (CPU) activates the relevant OS routines by switching to kernel mode, the shared data structures are implemented, allowing the routine to call other routines. The control goes back to the source routine and then the user program after the entire process is finished. Key Characteristics: All parts of the OS are combined into one single unit.

Easy to understand and develop.
Fast execution because everything is directly connected.

2. Layered Structure

In a layered operating system (OS), the entire software is divided into layers. Each layer is built on top of the others, making it easier to arrange components and manage them efficiently. In this particular structure, the lowest layer communicates with the hardware elements, whereas the topmost layer interacts with the user. Here, each layer operates independently, with no dependencies on the others.
(Working Mechanism)

So basically, the OS is structured into multiple layers, such as the hardware layer, the device driver layer, the user program layer, and others. Each layer in this particular structure provides particular services that are hidden for security reasons. When a user program starts running, the request propagates from the top layer to the bottom.

Once it reaches the hardware components, the hardware system processes it and sends it back, passing through various layers along the way. While this request-response cycle is active, each layer deals with the layer above or below it, keeping the entire system modular and efficient.

3. Structure with Modules

A modular operating system (OS) is built from several small units, known as modules, and each module in this structure is assigned a specific job, such as memory management, file management, or device management. All the modules in this structure are connected to a centralized source — the main kernel —which controls how modules interact without compromising their operational efficiency.

(Mechanism in Use) When the operating system (OS) is initially loaded, all modules are loaded along with it. After that, the main kernel system links the requested task to the appropriate module. Once connectivity is established, the module executes the assigned task using its own set of features and functionalities and shares the output via a standard interface. The control is returned to the kernel at the conclusion of this procedure.

Core Features:

It is simple to add or remove modules. Easier to expand and update without redesigning everything.
improves system control and organization.

4. Virtual Computers

Virtual machines are used in an operating system (OS) to enable a single computing unit to act as multiple separate computers. A processor, memory, storage, and device managers are just some of the components that each virtual machine that processes software uses in this structure. Consequently, system resources are divided by functionality, and each virtual machine has its own independent environment. The virtual machine monitor (VMC), which enables us to run multiple processes concurrently without interference, makes this entire procedure possible. (Mechanism in Use) When a user turns on the computer system, the virtual machine monitor (VMC) is the first software to run, gaining complete control of the hardware and enabling it to host multiple virtual machines at once. The system’s memory, processor, and storage are then distributed among all VM units by the monitoring unit. After this phase, each virtual machine is assigned its own OS, CPU, memory, and disk. And when an application is now executed inside a VM, and it fails to return a result or is affected by a virus, others can keep operating safely and securely.