Understand how different ports provide connection to peripheral devices

4.1 Central Processing Unit (CPU) Architecture

What is a CPU? 🧠

The CPU is the brain of a computer. It fetches instructions, decodes them, and executes operations. Think of it as a super‑fast chef that follows recipes (programs) to prepare dishes (results).

CPU Ports: The Doors to the Outside World 🔌

Ports are like doors on the CPU’s house. They let data flow in and out, connecting the CPU to peripheral devices such as keyboards, mice, displays, and storage.

• Serial Ports – one wire at a time, like a single‑lane road.
• Parallel Ports – multiple wires at once, like a multi‑lane highway.
• USB – universal, plug‑and‑play, the modern “smart door.”
• PCI/PCIe – high‑speed lanes for graphics cards and SSDs.
• Memory‑Mapped I/O – treats peripheral addresses as part of memory.

How Ports Connect to Peripheral Devices 📺🎮

When a peripheral wants to send data, it writes to a specific port address. The CPU reads that address, processes the data, and may write back a response.

1. Peripheral sends data to a port address (e.g., 0x3F8 for a serial port).
2. CPU’s Input/Output (I/O) controller detects the write and stores the data.
3. CPU fetches the data during its next cycle, decodes the instruction, and acts.
4. CPU writes a response back to the same or another port.

Exam Tip Box 📚

Port Types Comparison Table 📊