Unit 3 Session 8: I/O Ports and the I/O System | IT 231 BBA Slides

--:-- --
↓ Scroll for more

Unit 3 · Session 8

I/O Ports and the I/O System

IT 231: IT and Applications (BBA)

🎯 Learning Objectives

By the end of this session, you will be able to:

  • ✅ Define an I/O port and its function.
  • ✅ Identify common I/O ports like USB and HDMI.
  • ✅ Define the system bus and its role in the computer.

Understanding I/O Ports and Buses

Connecting Peripherals: What is an I/O Port?

An I/O (Input/Output) port is a physical connector on a computer that allows you to connect external peripheral devices.

Think of them as the doors and windows of your computer, letting information in and out.

Common I/O Ports 🔌

USB (Universal Serial Bus)

  • The most common and versatile port.
  • Connects keyboards, mice, printers, external drives, and more.
  • Provides both data transfer and power.

HDMI (High-Definition Multimedia Interface)

  • Transmits high-definition video and audio.
  • Connects your computer to monitors, TVs, and projectors.
  • A single cable for both picture and sound.

🎬 USB-C: One Port, Three Jobs

🚀 Same Plug, Different Speeds

  • USB 2.0: 480 Mbps
  • USB 3.2 Gen 1 (formerly USB 3.0): 5 Gbps
  • USB 3.2 Gen 2: 10 Gbps
  • USB4: up to 40 Gbps (80 Gbps with USB4 Version 2.0)

The plug shape doesn't tell you the speed. A cheap USB-C cable may only carry USB 2.0 speeds.

🧮 Worked Example: Copying a 10 GB Folder

Port speeds are in bits, but file sizes are in bytes. 1 byte = 8 bits, so 10 GB = 80,000 megabits.

  • USB 2.0: 80,000 ÷ 480 ≈ 167 s, almost 3 minutes
  • USB 3.2 Gen 1: 80,000 ÷ 5,000 = 16 seconds
  • USB 3.2 Gen 2: 80,000 ÷ 10,000 = 8 seconds

These are best cases. Real transfers are slower, and the slower of the drive and the port sets the limit.

🇪🇺 Case Study: One Charger for Everything

  • The European Union requires USB-C charging on new phones, tablets, cameras and headphones sold from 28 December 2024, and on laptops from 28 April 2026.
  • Apple moved the iPhone from its own Lightning port to USB-C with the iPhone 15 in 2023.
  • The aim: less e-waste and fewer chargers in every drawer.

Discuss: Who wins and who loses when a government standardises a port: users, manufacturers, or accessory sellers?

More Common I/O Ports 🎧🌐

Audio Jacks (3.5mm)

  • Used for connecting headphones, speakers, and microphones.
  • Often color-coded:
    • Green: Audio Out (speakers/headphones)
    • Pink: Mic In

Ethernet Port (RJ-45)

  • For a wired network connection.
  • Provides a faster and more stable connection than Wi-Fi.
  • Essential for gaming and large file transfers.

🎬 Wi-Fi vs Ethernet: The Numbers

🔍 Activity: Port Spotting in Nepal

Look around you!

Examine your laptop, a desktop in the lab, or even a smart TV. How many of these ports can you find?

  • USB (Type-A, Type-C?)
  • HDMI
  • Ethernet
  • Audio Jack

Context: In many offices and homes in Nepal, the Ethernet port is crucial for a stable internet connection, especially when power cuts or "load shedding" affect Wi-Fi router stability.

🔌 Activity: Which Cable Do I Need?

Name the port or cable for each job, then reveal.

  1. Laptop to a TV or modern projector. Answer: HDMI
  2. Charging a recent Android phone or an iPhone 15. Answer: USB-C
  3. Wired internet for a lab PC. Answer: Ethernet (RJ-45)
  4. Wired headphones on a laptop. Answer: 3.5 mm audio jack (or a USB-C adapter)
  5. One cable for charging, data and a 4K monitor. Answer: USB-C, if the port and cable support video

From Ports to the Core ⚡

So, these ports let us connect devices to the computer.

But how do the ports, the CPU, and the RAM all talk to each other inside the machine?

Answer: The System Bus

The System Bus: The Computer's Highway 🛣️

The system bus is the communication pathway that connects all the major components of a computer, including the CPU, RAM, and I/O ports.

It is the data superhighway built into the motherboard, allowing data to travel between all the different parts of the computer.

Anatomy of the System Bus

The system bus is actually made of three separate buses working together:

1. Data Bus

Carries the actual data being transferred.

2. Address Bus

Carries the information about where the data is supposed to go (the memory address).

3. Control Bus

Carries control signals from the CPU to coordinate all activities.

🎬 One Memory Read, Three Buses

System Bus Analogy: A Postal Service 📮

Data Bus is the...

Package

(The actual information)

Address Bus is the...

Delivery Address

(Where the package is going)

Control Bus is the...

Postman's Instructions

('Deliver', 'Sign Here', etc.)

🧮 How Wide Is the Highway? Bus Width

  • Data bus width is like the number of lanes. A 64-bit data bus carries 8 bytes in each transfer.
  • Address bus width sets how many addresses exist. Each extra wire doubles the count.

Try it: a 16-bit address bus gives 216 = ? addresses. 65,536, or 64 KB of memory.

A 32-bit address bus gives 232 ≈ 4.3 billion addresses, which is why 32-bit Windows couldn't use more than about 4 GB of RAM.

Discussion: The Bottleneck Effect

Using the highway analogy, what would happen if the system bus was too slow for the CPU?

It creates a bottleneck.

A fast CPU with a slow bus is like a Ferrari stuck in Kathmandu's traffic. The overall system performance is limited by its slowest component.

Kathmandu Traffic at Koteshwor

Motorbikes, a microbus and buses packed onto the road at Koteshwor, Kathmandu

Summary & Key Takeaways 📊

  • I/O ports are the physical sockets that allow us to connect external devices to a computer.
  • USB is the most common and versatile I/O port, handling both data and power for many devices.
  • The System Bus is the internal highway on the motherboard connecting the CPU, RAM, and I/O ports.
  • The bus is composed of a Data Bus, an Address Bus, and a Control Bus.

Image & Video Credits

Images (Wikimedia Commons)

Videos (YouTube)

  • Marques Brownlee, "USB Type-C: Explained!" (1:48 to 2:43)
  • Peezs, "Wireless (Wi-Fi) vs Wired (Ethernet) Connection - Speed/Latency Tests & Gaming Comparison" (2:18 to 3:32)
  • TeachingCS, "Computer Architecture - System Bus (address, data & control)" (2:33 to 3:46)

Exam Practice 📝

Short answer

  1. What is an I/O port? Name four common ports and their uses.
  2. Differentiate between serial and parallel ports.
  3. What is bus width?

Long answer

  1. Explain the system bus and its three components.
  2. Describe common I/O ports found on modern computers and explain why USB has become the most popular.

Revise the answers in the full note linked on the last slide.

Thank You

Questions before we wrap this hour?

Next: Unit 4 · Session 1 — Software Types: System and Application

Course Home · Next session

📖 Read the full note