Computer System
Senior 1 · ICT
Computer System
Lesson 3 of 5
18 min
Let's begin
The school has bought a new projector for the hall. The ICT teacher holds up a cable and asks: "Which hole on the laptop does this go into?" To answer, you need to know the devices that connect to a computer and the ports they plug into.
Hardware is the physical parts of a computer system. External hardware, also called peripherals, is connected to the outside of the computer: keyboards, printers, speakers and so on.
An input device sends data or instructions into the computer.
| Device | What it inputs |
|---|---|
| Keyboard | Letters, numbers and commands |
| Mouse and touchpad | Pointer movements and clicks |
| Microphone | Sound, such as speech |
| Scanner | Images of paper documents and photos |
| Webcam and digital camera | Photos and video |
| Barcode reader | Product codes at a supermarket till |
| Fingerprint scanner | Fingerprints, to identify a person |
An output device presents results from the computer to the user.
| Device | What it outputs |
|---|---|
| Monitor (screen) | Text, pictures and video |
| Printer | Text and pictures on paper (hard copy) |
| Speakers and headphones | Sound |
| Projector | A large picture on a wall or screen |
Some devices do both: a touchscreen shows output and takes your touch as input; a headset has headphones (output) and a microphone (input).
A port is a socket on a computer where a cable or device plugs in. The plug at the end of the cable is the connector. Each port has its own shape, so a cable only fits the right one.
| Port | How to recognise it | Used for |
|---|---|---|
| USB Type-A | Flat rectangle; fits only one way up | Flash drives, mice, keyboards, printers |
| USB Type-C | Small rounded oval; fits either way up | Charging, fast data, and on many devices video |
| HDMI | Wide, flat, with two slanted corners | Digital picture and sound to a TV, monitor or projector |
| VGA | Older, usually blue, with 15 small holes in three rows | Picture only (analogue) to older monitors and projectors |
| Ethernet (RJ45) | Square socket with a clip, like a large phone socket | A wired network or internet connection |
| Audio jack (3.5 mm) | Small round hole | Headphones, speakers, microphone |
| Power (DC-in) | Round socket or USB-C | The charger |
| Card slot | Thin slit | SD or microSD memory cards |
Uwase's laptop has HDMI and USB ports. The school's old projector has only a blue VGA port.
Handle ports with care: push connectors in straight and never force them the wrong way up; hold the plug, not the cable, when pulling it out; eject a flash drive safely before removing it.
Tip
In or out? Ask which way the data travels. Into the computer: input. Out to you: output. Both ways: a device such as a touchscreen does both.
HDMI carries sound; VGA does not.
Classify as input, output or both: printer, microphone, touchscreen, webcam, speakers.
Solution: Input: microphone, webcam. Output: printer, speakers. Both: touchscreen.
Which port would you use to (a) connect a TV so that both picture and sound come through one cable, (b) plug in a flash drive, (c) join a wired school network?
Solution: (a) HDMI; (b) USB (Type-A, or Type-C for a USB-C drive); (c) Ethernet (RJ45).
A shop worker slides a tin of milk past a red light and its price appears on the screen. Name the input device and the output device.
Solution: Input: the barcode reader. Output: the monitor (screen). A printer then prints the receipt, another output.
What is the difference between a port and a connector?
Solution: The port is the socket on the computer; the connector is the plug on the end of the cable that goes into it.
Remember
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
