Lesson Notes By Weeks and Term v4 - SHS 1
DATA COMMUNICATION AND NETWORK SYSTEMS
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DATA COMMUNICATION AND NETWORK SYSTEMS
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Subject: Computing
Class: SHS 1
Term: 2nd Term
Week: 3
Grade code: 1.1.3.LI.2
Strand code: 1
Sub-strand code: 3
Content standard code: 1.1.3.CS.1
Indicator code: 1.1.3.LI.2
Theme: COMPUTER ARCHITECTURE AND ORGANISATION
Subtheme: DATA COMMUNICATION AND NETWORK SYSTEMS
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Good day, learners. Today, we are diving into the exciting world of Data Communication and Network Systems. Think about how you use your phone to watch videos on YouTube, send money with Mobile Money (MoMo), or how we use computers in the ICT lab to access the internet. All of these activities are possible because of computer networks. A network is simply a group of connected devices that can share information. But how do they connect? What magical boxes and cards make this happen? This lesson is crucial because it demystifies the internet.
What is a Computer Network?
Before we look at the parts, let's understand the whole system. A computer network is a collection of computers, printers, and other devices connected together so they can share resources and data.
For context, there are different types of networks based on size: LAN (Local Area Network): A network in a small area, like our school's ICT lab, an office building, or your home. WAN (Wide Area Network): A network that covers a large geographical area, like a city or even a country. The biggest WAN we all know is the Internet.
Now, let's look at the special hardware that builds these networks. A. The Network Interface Card (NIC) What is it? A NIC is a piece of hardware, usually a small circuit board, that is installed inside a computer (desktop, laptop). It's the physical point of connection between the computer and the network. Every device that connects to a network needs one. Your smartphone has a built-in wireless NIC! What does it look like? For a desktop, it's a card with a special port on the back of the computer case. This port is where you plug in the network cable (usually an RJ-45 cable). Laptops have this port built into the side. Wireless NICs might just be an internal chip with an antenna. What is its main function? Provides a Physical Connection: It gives the computer a dedicated port to connect to the network. Provides a Unique Address: Every NIC has a unique physical address burned into it called a MAC Address (Media Access Control Address). This is like your digital fingerprint or the unique serial number on your phone. No two NICs in the world have the same MAC address. Ghanaian Analogy: A NIC is like your Ghana Card. It gives you a unique identification number (the MAC Address) and proves you are a legitimate entity that can interact with the national system (the network). Without it, you cannot be identified. B. The Switch What is it? A switch is a networking device that connects multiple devices together on a single computer network (a LAN). What does it look like? It's a flat, rectangular box with many ports on the front (from 4 up to 48 ports). Each port can be connected to a computer, printer, or another network device with a cable. What is its main function? A switch is an intelligent device. When it receives a piece of data (called a "frame"), it looks at the destination MAC address and sends the data *only* to the specific device it is intended for. It creates a direct line of communication between the sender and the receiver. Ghanaian Analogy: A switch is like the sorting office at the Ghana Post. When a letter arrives for someone in a specific office building (the LAN), the switch doesn't just shout the person's name in the lobby. It reads the specific office number (the MAC address) and delivers the letter directly to that person's desk (the device). This is efficient and private. C. The Router What is it? A router is a networking device that connects different networks together. Its main job is to forward data packets between these networks. For example, it connects your home or school LAN to the giant WAN, the Internet. What does it look like? It often looks similar to a switch, but usually has fewer LAN ports and a special port called a "WAN" or "Internet" port. Many modern routers, especially for home use, also have antennas for Wi-Fi (wireless) connections. What is its main function? Connects Different Networks: It acts as a gateway between your local network (LAN) and the outside world (WAN/Internet). Directs Traffic: It looks at the destination IP Address (Internet Protocol Address) of a data packet and decides the best path for that packet to take to reach its final destination, even if it's on the other side of the world. Ghanaian Analogy: A router is like the trotro mate or driver at a major lorry station like Circle or Kejetia. The lorry station (the router) connects many different routes (networks). When a passenger (data packet) arrives, the mate doesn't just put them on any bus. They check the passenger's final destination (the IP Address) and direct them to the correct trotro that is going towards Kasoa, or Madina, or Takoradi. The router finds the best route for your data. D. The Modem What is it? A modem (short for Modulator-Demodulator) is a device that connects your home or school network to your Internet Service Provider (ISP), like MTN, Vodafone, or Telecel. What does it look like? It's a small box that has a port to connect to the ISP's line (which could be a phone line, a fibre optic cable, or a coaxial cable) and another port (usually an Ethernet port) to connect to your computer or router. What is its main function? It acts as a translator. Computers on your network speak a digital language. The internet signal coming from your ISP over a phone line or fibre optic cable is often in a different format (e.g., analog). Modulation: It converts the outgoing digital signal from your computer into a signal that can travel over the ISP's line. Demodulation: It converts the incoming signal from the ISP back into a digital signal that your computer can understand. Ghanaian Analogy: A modem is like a language translator at a conference. If you only speak Twi (digital) and the guest speaker is speaking French (the ISP's signal), the translator (modem) listens to the French and translates it into Twi for you to understand, and vice-versa.