PrajnaEdge is not navigated like a conventional website. Knowledge is represented through paths, structures, and transitions.
Matter
NodeClick a node name to enter that concept and continue along the awakened path.
ExplorationsStep-by-step learning experiences containing theory, architecture, and interactive elements.
SetuA Setu connects related concepts that can be explored independently from the main sequence.
VortexA Vortex opens a path toward another knowledge area, foundation, or future domain.
BlackholeA deeper exploration space opened through the Vortex, where you select the depth of investigation.
AntarguhaA concealed exploration existing outside the regular path, waiting to be discovered within the system.
For the best experience, open PrajnaEdge on a desktop or laptop screen.
PrajnaEdge
A curiosphere for curious minds who want to understand, experiment with, and experience technology.
Technology is a system of connections.
Modern technology is built from layers that continuously interact with one another. At the physical level, electronic devices transform electrical signals into digital information. Digital logic turns that information into computation, while processors, memory and communication interfaces provide the machinery needed to execute instructions and move data. As these components become part of embedded systems, they begin to interact with the physical world through sensors, controllers, actuators and real-time software.
But computation does not exist in isolation. Operating systems coordinate hardware and software, firmware gives specialized machines their behaviour, and communication protocols allow independent systems to exchange information. At the same time, machine learning is moving beyond the cloud into edge and on-device systems, where models must operate within real constraints such as memory, processing power, latency and energy consumption.
PrajnaEdge explores these connections as one continuous technology landscape — and takes them beyond explanation. From computing foundations and embedded systems to intelligent machines and edge AI, ideas can be understood, experimented with, and eventually turned into technology that can be experienced in the real world.
PrajnaEdge products and technology experiences are currently in development.
In Development
Playground
Experiment with intelligence beyond the cloud.
AI runs closer to where data is generated — reducing dependence on distant cloud infrastructure and enabling faster, more responsive systems.
Edge AIComputer Vision
Image Classification
Can this image classifier maintain its intelligence while becoming small enough for the edge?
On-Device AIComing later
On-Device Intelligence
AI runs directly on the device where data is generated, bringing intelligence into the device itself while operating within its compute, memory, power and latency constraints.
Edge AI Playground
Image Classification
Can this image classifier maintain its intelligence while becoming small enough for the edge?
Choose an image
Upload an image
Supports JPG, JPEG, PNG
This classifier recognizes only Apple, Banana, and Orange. Other objects may be incorrectly classified as one of these classes.
AI runs directly on the device where data is generated, bringing intelligence into the device itself while operating within its compute, memory, power and latency constraints.
Coming later
Explorations
Explore the ideas, systems and connections that shape technology — choose any node to begin your journey.
Embedded Systems Tree
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Edge AI Demonstrations
Deploying neural networks and intelligent decision loops on raw silicon targets.
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Operating Systems
How Does the Filesystem Keep Track?
Demystifying persistent directories, metadata bookkeeping, and physical block allocation.
When an application creates a new file, the operating system must perform a lot of bookkeeping. Suppose your program requests:
notes.txt
To manage this file, the operating system cannot simply store a list of active filenames. It must be prepared to answer critical operational questions at any time:
* What does this file represent? Is it a regular file, a directory, a symbolic link, or a character device?
* How large is it? Where does the file end, and how many bytes are in use?
* Who owns it and who can access it? What are the read, write, and execute permissions?
* When was it changed? When was the file created, modified, or last opened?
* Where is its data? Which physical block sectors on the storage media hold the file's content?
* Which blocks are free? Where can the filesystem allocate space when the file expands?
* How does it survive a power loss? What happens to the metadata if the machine suddenly shuts down mid-write?
To resolve these questions, the operating system relies on persistent filesystem structures written directly onto the storage device.
2. The Conceptual Filesystem Structures
To organize this information, modern filesystems split their responsibilities among four major conceptual layers:
Directory Entries
The namespace is the human-facing interface of the filesystem. The directory structure answers: What name refers to which filesystem object?
Directory records are lookups mapping filenames to internal system identifiers:
File Metadata
Once the filename maps to an internal ID, the operating system accesses the metadata record. It answers: What is this file?
The metadata block contains everything about the file except its name or its raw data:
* File size (in bytes or sectors).
* Owner and group membership.
* Access permissions (Read/Write/Execute constraints).
* Timestamps (creation, modification, access).
* File type (regular, folder, link, etc.).
* Link count (number of directory entry references).
* Data location offsets (pointing to where the data blocks are located).
Data Allocation Information
To read or write the actual data payload, the OS consults the location map stored in the file's metadata. It answers: Where are the contents of this file stored?
Conceptually:
File #7182
↓
Block 209
Block 310
Block 311
The exact indexing mechanisms vary, ranging from sequential block indexes to extent maps (which reference a starting block and a run length).
Free-Space Tracking
When files grow or new files are created, the filesystem needs to know: Which storage blocks are available for new data?
Conceptually, the filesystem maintains a map of the drive:
[USED] [USED] [FREE] [USED] [FREE] [FREE] [USED]
The OS reads this structure to find free space quickly and update its markers as sectors are assigned.
3. The Key Realization
A filesystem is not just a bucket where you store files.
A filesystem is a collection of metadata and data structures that allow the operating system to find, describe, allocate, modify, and delete those files.
Without these background structures, the storage drive is merely a flat, raw string of addressable sectors. The filesystem is the translation machinery that converts raw sectors into a structured digital workspace.
4. EdgeCase: The Lifecycle of a File
Use the simulator below to trace how the operating system coordinates directories, metadata tables, space trackers, and storage sectors during the lifecycle of a file:
5. Important Conceptual Distinction
When you click "Delete" in the simulator above, notice that the physical data blocks are not wiped.
When a file is deleted, the operating system typically does not overwrite the physical sectors with zeros immediately. Instead, it:
1. Removes the name mapping from the directory.
2. Releases the metadata record (making its ID available for new files).
3. Marks the data blocks as "free" in the space tracker.
The old data remains physically readable on the drive sectors until it is overwritten by a subsequent write operation.
6. Real Operating-System Connection
While the concepts remain uniform, different operating systems organize their directories and metadata structures in unique ways:
Unix / Linux (ext4, XFS)
Linux filesystems separate names from properties using index nodes (inodes). Directory entry records map name strings directly to inode numbers. Each inode stands as a self-contained record pointing to the file metadata and data block pointers.
Windows (NTFS)
NTFS stores all file data and properties in a database called the Master File Table (MFT). MFT records contain the attributes of a file, such as its name, security permissions, and either the data itself (for very small files) or references to external data clusters.
macOS (APFS)
APFS uses a b-tree object map, dynamically scaling metadata nodes to manage file snapshots, space sharing, and quick lookups without hardcoded layout layouts.
Regardless of the on-disk implementation details, every operating system must provide matching mechanisms for directory names, metadata properties, data tracking, and free-space bookkeeping.
7. The Next Question
We now understand how the filesystem keeps track of files.
But what actually happens underneath the filesystem when it asks the storage device to read or write those blocks?
Engineering concepts you don't just read — you experience.
Founded in 2026.
PrajnaEdge is a technology company exploring the space between understanding technology, experimenting with ideas, and turning them into things that can be experienced.
Our Mission
To make technology easier to explore, deeper to understand, and more exciting to experience.
Our Vision
To build a technology ecosystem where curiosity, experimentation and creation continuously lead to one another.
Where it began
Embedded Systems
PrajnaEdge began with Embedded Systems — exploring the foundations that connect hardware, software and intelligent computation.
The first technology universe is built around that foundation. The journey will expand as new ideas, experiments and products emerge.
I am the engineer behind the design, development, and content of PrajnaEdge. I build low-level systems where code directly controls hardware, bridging the gap between register-level silicon behavior and intelligent edge decision loops.
I am an Embedded Firmware Engineer focused on developing software for resource-constrained systems. My experience spans bare-metal firmware, device drivers, microcontroller peripherals, and communication protocols, working across the boundary between hardware and software.
My work has involved microcontroller-based systems, real-time behaviour, hardware interfaces, and communication technologies such as CAN, CAN FD, UART, SPI, and I²C. I am particularly interested in understanding systems from the lowest level upward—from registers and peripherals to intelligent edge systems.
ENGINEERING PHILOSOPHY
Engineering is not just about writing code; it is about managing constraints, timings, and physical hardware characteristics. True mastery of complex systems comes from understanding the interactions across different layers of the stack.
This conviction is why I built PrajnaEdge—to bridge the gap between conceptual theory and direct, register-level physical reality.
Where it all began — understanding the physical layer of computation. Circuits, signals, and systems gave me a mental model of how information moves through hardware.
⬡
Connects to Systems Understanding circuits directly enables writing firmware that talks to peripherals at the register level.
What it is
BTech in Electronics and Communication
Undergraduate foundation covering analog & digital circuits, signal processing, microprocessors, and communication systems.
CircuitsSignal ProcessingMicroprocessorsVLSI
What I did
Core Engineering Fundamentals
Studied semiconductor physics, digital logic design, and embedded microcontrollers. Built prototypes using 8-bit MCUs.
8051Logic DesignPCB Basics
What I learned
The Hardware Mental Model
Every software abstraction sits on physical reality. Understanding silicon teaches you why timing, power, and noise are first-class engineering problems.
Let's Connect
Interested in embedded systems, AI, or building something meaningful? I'd love to hear from you.
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Legal & Privacy
Last updated: September 2026
1. Terms of Use
Welcome to PrajnaEdge (prajnaedge.dev), an independent engineering and technology platform created and maintained by Devaharsha Meesarapu. By using this website, you agree to these terms.
Educational & Research Focus: PrajnaEdge publishes interactive technical explorations, architectural models, and simulation walk-throughs covering embedded systems, computer architecture, operating systems, and edge artificial intelligence. All materials, interactive tools, and code demonstrations are provided solely for educational and conceptual understanding.
Hardware & Firmware Disclaimer: Embedded programming interacts directly with hardware registers, physical voltages, and precise timing. While all writeups and code demonstrations are prepared with care, they are provided "as is" without warranty of any kind. You are responsible for reviewing component datasheets, circuit schematics, and electrical ratings before deploying code to physical microcontrollers or custom hardware.
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