Information Technology · Ch 1 — Introduction to Computer System
The Communication Bus and Ports
The Communication Bus and Ports
The different units of a computer — CPU, memory, and input/output devices — must be able to send data and signals to one another. This is done through the communication bus inside the computer and the ports on the outside of the computer's cabinet.
The system bus. A bus is a set of parallel wires (electrical pathways) along which data, addresses, and control signals travel between the parts of the computer. It works like a common road that connects the CPU, memory, and I/O devices. The main system bus is made up of three parts, each carrying a different kind of information:
- Data bus. Carries the actual data being moved between the CPU, memory, and devices. It is bidirectional — data can travel in both directions. The width of the data bus (how many bits it can carry at once) affects how much data can move in one step.
- Address bus. Carries the address (location) in memory or the device that the CPU wants to read from or write to. It is unidirectional — addresses flow out from the CPU. The width of the address bus decides how much memory the CPU can access.
- Control bus. Carries the control signals (commands and timing signals) from the control unit to the other units — for example, signals that say "read" or "write" — so that everything happens in the right order.
Ports. A port is a socket or connection point on the outside of the computer's cabinet into which an external device is plugged. Data passes between the computer and the outside device through the port. Common ports include:
- USB (Universal Serial Bus) port — the most widely used general-purpose port today, used for the keyboard, mouse, pen drive, printer, camera, and many other devices; it is fast and easy to plug in.
- Display ports — such as the VGA and HDMI ports, used to connect the monitor or projector (HDMI carries both picture and sound).
- Audio ports — small round jacks used to connect speakers, headphones, and a microphone.
- Network (LAN/Ethernet) port — used to connect the computer to a wired network or the internet. …