DEV Community: Ankit Thakur

Paging In OS

Ankit Thakur — Tue, 01 Sep 2026 16:19:41 +0000

Paging in Operating System

Paging is a memory management technique used by an Operating System (OS). It is used to manage the main memory efficiently and allows a process to use memory even when its data is not stored continuously in physical memory.

In paging, the logical memory of a process is divided into fixed-size blocks called pages, while the physical memory (RAM) is divided into fixed-size blocks called frames. The size of a page and a frame is always the same.

How Paging Works

When a program is executed:

The program is divided into fixed-size pages.
The main memory is divided into fixed-size frames.
The OS loads the required pages into available frames.
A page table is maintained by the OS to keep track of which page is stored in which frame.
When the CPU generates a logical address, the OS uses the page table to convert it into a physical address.
Example

Suppose a process has 4 pages:

Page 0
Page 1
Page 2
Page 3

And RAM has available frames:

Frame 0
Frame 1
Frame 2
Frame 3

The pages do not have to be stored continuously. For example:

Page Frame
Page 0 Frame 2
Page 1 Frame 0
Page 2 Frame 3
Page 3 Frame 1

The page table stores this mapping.

So, if the CPU wants to access Page 2, the OS checks the page table and finds that Page 2 is present in Frame 3.

Logical and Physical Address

A logical address in paging is divided into two parts:

Logical Address = Page Number + Offset

Page Number: Identifies the page.
Offset: Identifies the exact location inside that page.

The page number is used to find the corresponding frame from the page table. Then the frame number and offset are combined to create the physical address.
Advantages of Paging
It reduces external fragmentation.
Memory can be used more efficiently.
A process does not need to be stored in continuous memory.
It makes virtual memory possible.
Memory allocation becomes easier for the OS.
Disadvantages of Paging
It requires extra memory for maintaining page tables.
Address translation can increase memory access time.
It can cause internal fragmentation, especially when a page is not completely filled.
Large processes may require large page tables.

Types of Operating Systems

Ankit Thakur — Sun, 07 Jun 2026 08:24:04 +0000

An operating system is the software that manages your computer's hardware and provides services to applications. But not all operating systems are built alike — different use cases call for very different designs.

What is an Operating System?
Think of an OS as the bridge between you and your hardware. When you click "open file," the OS handles the disk read, memory allocation, and screen rendering — all invisibly. Without it, every app would need to talk directly to hardware, which would be chaos.

Batch OS

Jobs collected and executed in groups without user interaction. Early IBM systems used this.

Time-Sharing OS

Multiple users share the CPU simultaneously via rapid context switching. Unix is a classic example.

Real-Time OS

Guarantees task completion within strict time deadlines. Used in pacemakers, flight systems.

Distributed OS

Multiple machines appear as one unified system. Powers cloud computing platforms.

Embedded OS
Lightweight OS designed for specific hardware devices like routers, smartwatches, or printers.

fundaments of OS

Ankit Thakur — Thu, 18 Dec 2025 14:46:49 +0000

-: What is an Operating System?
Okay Lets understand Operationg System without knowing its actual definition suppose we have a computer and we want to Store something into our Memory So how will you store it without an operating system. I think you are blank now so You have to convert into binary number system and give to the hardware then store it. Lets take one more example what if I say you can’t open your devices without help of OS I know it is little bit surprising If you Don’t use OS then occur this Issues such as bulky and complex app(Hardware attraction must be System Software)(System Software is basically operates your Application Software), In easy word which application help us in providing basic interfaces such as file management, memory management, System Security, software updates)and Application software is provide actual works such as specific user tasks Such as video editing , Coding IDES & environment, there are so many examples) Operating system central part is Kernel, A kernel is the core component of an (OS)serving as the essential foundation that provides basic services for all other parts of the OS .

Function of OS:-
*Its provides user interface between user devices with its hardware.
*Resource Manger (OS manages all the things our pc).
*Hides Complexities (without knowing how data stores into memory ).

Thnaku!