1. What is a digital system?
A digital system is hardware and software working together to do four jobs, in order:
Hardware is the physical parts you can touch (keyboard, screen, the chips inside). Software is the programs that run on it (games, a web browser, the code you write).
2. Input & output
An input device sends data into the computer. An output device sends data out to you. A quick way to tell them apart: input is how you talk to the computer; output is how the computer talks back.
| Input (data in) | Output (data out) |
|---|---|
| Keyboard, mouse | Monitor (screen) |
| Microphone | Speakers, headphones |
| Webcam, scanner | Printer |
Check your understanding: Which of these is an output device?
A printer takes data from the computer and puts it out onto paper, so it is an output device. Keyboard, microphone and webcam all send data in, so they are inputs.
Exam practice
Name THREE different input devices. (1 mark)
Show what earns the marks
- 1 mark for three correct input devices, for example: keyboard, mouse, microphone, webcam, scanner, game controller, touchscreen.
- You get 0 if any of your three is an output device (printer, monitor or speakers). Read the question carefully!
3. Sort the devices
Tap a device, then tap the bin it belongs in: Input, Output or Storage. Then press Check.
Input
Output
Storage
4. Storage
A storage device keeps data for later, even when the power is off. Examples: a hard drive (HDD), a faster solid state drive (SSD), a USB stick or an SD card. Storage is measured in the units you met in the Binary module: KB, MB, GB.
You try
Your school laptop is almost full. Write down three things you could do to free up space (and why each helps). Hint: think about files you no longer need, apps you do not use, and moving things somewhere else.
5. The processor (CPU)
The processor, or CPU, is the brain of the computer. It does the process step: it follows the program's instructions, does the maths and the decisions, billions of times a second. When you hear a computer is "fast", that is mostly the CPU.
6. RAM vs ROM
These two sound alike but do opposite jobs:
| RAM | ROM | |
|---|---|---|
| Job | Working memory the computer uses right now | Permanent instructions to start up |
| When the power goes off | It is wiped (temporary) | It stays (permanent) |
Check your understanding: Which memory is temporary and gets wiped when you turn the computer off?
RAM is the computer's short-term working memory, and it is wiped every time the power goes off. ROM keeps its data permanently and holds the instructions that start the computer up.
Module test
Five quick questions to check you have got it. Your best score shows on your My Progress page.
1. Which of these is an input device?
2. What is the main job of the processor (CPU)?
3. Which memory is temporary and is wiped when the power goes off?
4. Which of these is a storage device?
5. A digital system does four jobs. What is the right order?
Class word clouds
Every gadget is a digital system. Add one you have used today.
Round 2: what is INSIDE them?
Now zoom in. Pick a component from inside a digital system, and tag what kind of part it is. The colours show how the class sorted them, so you can spot arguments at a glance (is a touchscreen input or output?). Two words are fine, like hard drive.
Glossary
- Digital system
- Hardware and software working together to input, process, store and output data.
- Hardware
- The physical parts of a computer you can touch.
- Software
- The programs that run on the hardware.
- Input device
- Sends data into the computer (keyboard, mouse, microphone).
- Output device
- Sends data out to the user (monitor, speakers, printer).
- Storage device
- Keeps data for later, even when off (hard drive, SSD, USB stick).
- CPU (processor)
- The brain that follows instructions and processes data.
- RAM
- Temporary working memory, wiped when the power is off.
- ROM
- Permanent memory holding the start-up instructions.