A computer is a complex device but having a basic idea of the building blocks can help understand enough to make sensible choices of devices.
The image below is a simplified diagram of the major elements of a computer.
It does NOT show the electrical connections between each part.
The parts and their functions are described below:
| Component | Function | Desk Computer | Laptop | Tablet | Mobile Phone |
| Processing | Computing instructions from apps & user | Yes | Yes | Yes | Yes |
| Working Memory | Storing instructions and results | Yes | Yes | Yes | Yes |
| Long Term Storage | Storing apps & data | Yes | Yes | Yes | Yes |
| Power | Provides power to all parts | Yes | Yes | Yes | Yes |
| Screen or Monitor | Displays information to user | Yes | Yes | Yes | Yes |
| Video | Stores information for display | Yes | Yes | Yes | Yes |
| Touch Control | Monitors input by user | Keyboard | Keyboard/screen | Screen | Screen |
| Position | Measures device tilt | No | Some | Yes | Yes |
| Cellular | SIM & Connection to mobile network | No | Some | Some | Yes |
| GPS | Global Position, location on earth from satellites | No | No | Yes | Yes |
| Bluetooth | Local wireless connection to accessories | Some | Some | Yes | Yes |
| WiFi | Wireless connection to internet | Some | Yes | Yes | Yes |
| Sound | Audio output to speakers or headphones | Yes | Yes | Yes | Yes |
| Wired | Cable based connection to other devices (USB cable etc) | Yes | Yes | Yes | Yes |
The most important parts to consider are:
Size of the Working Memory, measured in Gigabytes, typical sizes shown in the image.
- Where memory is concerned, more is better.
- On a desktop or laptop computer this memory is usually referred to RAM (random access memory)
Size of the Long Term Storage, measured in Gigabytes, typical sizes shown in the image.
- Up to a point, more is better but also consider budget impacts
- Long Term Storage can be a 'hard drive' or 'flash memory' (no mechanical parts)
- Hard drives are usually slower but larger and used on desktop computers.
- Flash memory is usually faster, more expensive and used on laptops, tablets and mobile phones.
- Desktop computers can use flash memory in Solid State Drives for greater speed at higher cost.
Power of the Processing unit. Newer is generally faster.
To use Cellular function, the connection to the mobile phone network is made using a SIM card
- This is essential in a mobile phone
- Optional at higher cost in tablets. Using a SIM card for data from the mobile phone network.
- Some laptops include this as an option for data only (no phone calls)
Images and Video
A desktop computer can plug in a camera
Laptop computers usually have a camera built in above the screen
Tablets and mobile phones usually have a camera at the back and another at the front (for 'selfies')
