Tech With Phill Technologies

22/01/2026

Most products in the U.S. use a 12-digit UPC barcode. Each section tells you something different.

1. First digit — Number system / country code
• The first number identifies the number system used.
• In many cases, it reflects where the barcode was registered, not where the product was made.
• Example: Numbers starting with 0 or 1 are commonly registered in the United States.

2. Next five digits — Manufacturer code
• These numbers identify the company that registered the product.
• Larger companies usually get shorter manufacturer codes so they can list more products.

3. Next five digits — Product code
• This part identifies the specific item made by that manufacturer.
• Different sizes, flavors, or versions of the same product get different product codes.

4. Last digit — Check digit
• This number is used to verify accuracy.
• It is calculated from the other digits using a formula.
• If the barcode is scanned incorrectly, the check digit tells the system something is wrong.

Important thing most people misunderstand

The barcode does not tell you where the product was manufactured.

A product can:
• Have a U.S. barcode
• Be registered by a U.S. company
• Still be manufactured overseas

The barcode identifies who registered the product, not where it was made.

17/01/2026

CODING IS LOVE

28/12/2025

📁 File System — Simple Explanation
A file system is the method an operating system uses to store, organize, manage, and retrieve data on a storage device (like a hard disk, SSD, USB drive, or memory card).

Think of it like a library system:

Books = files

Shelves & sections = folders/directories

Library rules = file system

🔹 What Does a File System Do?

1. Stores data in files

2. Organizes files into folders (directories)

3. Keeps track of file locations on the disk

4. Controls access & permissions

5. Manages space efficiently

6. Protects data from corruption

🔹 Basic Components

1️⃣ Files

Contain data (text, images, videos, programs)

Have a name, size, type, and permissions

2️⃣ Directories (Folders)

Hold files and other folders

Create a hierarchical structure

3️⃣ Metadata

Information about files (created date, owner, permissions)

4️⃣ Storage Blocks

Physical space where data is stored on the disk

🔹 File System Hierarchy

Most operating systems use a tree-like structure:

Root (/ or C:\)

├── Home / Users

│ └── Documents

│ └── file.txt

├── System

└── Applications

🔹 Common Types of File Systems

🪟 Windows

FAT32 – Older, compatible with many devices

NTFS – Secure, supports large files

🐧 Linux

EXT4 – Most common, fast & reliable

XFS – Used for large storage systems

🍎 macOS

APFS – Optimized for SSDs

🔹 Why File System Is Important?

✔ Without it, data would be random

✔ Faster file access

✔ Better security & permissions

✔ Prevents data loss

✔ Efficient storage usage

🔹 In One Line

> A file system is the backbone of data storage that tells the OS where and how files live on a disk.

28/12/2025

UEFI vs Legacy (BIOS) — simple & clear 🔧

🔹 What is Legacy (BIOS)?

Old firmware system (1980s)

Uses MBR partition style

Supports disks up to 2 TB

Slower boot

No Secure Boot

Limited features

🔹 What is UEFI?

Modern replacement for BIOS

Uses GPT partition style

Supports disks larger than 2 TB

Faster boot

Secure Boot support

Mouse + better UI

Required for modern OS features

⚔️ Quick Comparison

Feature Legacy (BIOS) UEFI

Age Old Modern
Disk Type MBR GPT
Max Disk Size 2 TB Very large (ZB range)
Boot Speed Slow Fast
Secure Boot ❌ No ✅ Yes
UI Keyboard only Mouse + GUI
Windows 11 ❌ Not supported ✅ Required
Linux Support Limited Excellent

🧠 Which should you use?

✅ Use UEFI → New PC, SSD/NVMe, Windows 10/11, Linux (Parrot, Kali, Ubuntu)

❌ Use Legacy → Very old hardware or old OS only

Since you use Linux, VirtualBox, and modern hardware →
👉 UEFI + GPT is the BEST choice
It gives better performance, security, and future-proofing.

27/11/2025

Firewall vs IDS vs IPS: Easy to Understand

Firewall: Think of a firewall like a gatekeeper. It checks everyone trying to enter and stops anyone who shouldn’t be there. "No entry after 7 PM."

IDS (Intrusion Detection System): IDS is like a security camera. It watches for suspicious activity and sends an alert if something’s wrong. "No weird behavior after 7 PM."

IPS (Intrusion Prevention System): IPS is like a bouncer. It not only sees trouble but also stops it right away, blocking bad traffic. "I don’t just watch; I stop the troublemakers."

21/09/2025

Understanding IPv4 Address Classes

An IP Address is like the identity card of every device on a network . In IPv4, addresses are divided into 5 classes:

🔹 Class A: 0.0.0.0 – 127.255.255.255
🔹 Class B: 128.0.0.0 – 191.255.255.255
🔹 Class C: 192.0.0.0 – 223.255.255.255
🔹 Class D: 224.0.0.0 – 239.255.255.255 (Multicasting)
🔹 Class E: 240.0.0.0 – 255.255.255.255 (Research & Experimental)

Special Reservations:

■ 0.0.0.0 → Default routing
■ 127.0.0.0 → Loopback testing
■ Class D → Multicasting
■ Class E → Research

Private IP Ranges (used in LAN):

■ Class A: 10.0.0.0 – 10.255.255.255
■ Class B: 172.16.0.0 – 172.31.255.255
■ Class C: 192.168.0.0 – 192.168.255.255

Public IP Ranges (used on the Internet):

Class A, B, C (excluding private ranges)

In simple terms:

Private IP = Used inside your home/office network.
Public IP = Used on the internet.

11/09/2025