Operating Systems
An operating system (OS) is software which…
- controls everything a computer does
- provides a platform to run applications
- controls all hardware
- provides an interface for us to use
There are many modern operating systems, but they can be put into just three categories: Unix, Linux, and Windows.
Click a button to find out about each family of operating systems.
Unix
Linux
Windows
Unix Operating Systems
Originally created in 1969 by Bell Labs (a US phone company), Unix was developed as a multi-user operating system. This means that lots of different users could use the computer at the same time, logging in via "terminals" – systems which provided an interface but did not do any of the computing.
Modern Unix operating systems include:
- MacOS (used on Apple desktop and laptop computers)
- iOS (used on Apple iPhones)
- iPadOS (used on Apple iPads)
Linux
Linux is heavily based on Unix, but is not part of it. It is open-source software, meaning anyone can modify the source code to make their own version (called a distro).
Linux is very efficient and can be configured to use few system resources. This makes it a good choice for using on embedded systems which have limited processing and storage.
Examples of Linux operating systems:
- Linux (mostly used on servers and embedded systems)
- Android (used on phones, tablets, and a variety of "smart" devices)
- ChromeOS (used on Chromebooks)
- Ubuntu (used on desktop computers, servers, and high-specification computing devices)
Do not confuse ChromeOS (the operating system) with Chrome (the web browser).
Windows
Windows is proprietary software produced by Microsoft. It powers the majority of desktop and laptop PCs used across the world.
Is is also the operating system used by Microsoft's Xbox range of games consoles.
PC vs Mobile HCI: Key Differences
Hardware limitations (such as screen size) influence the design of the interface provided by the operating system. Key differences between interfaces designed for full-sized and mobile screens include:
Icons
Desktop / Laptop HCI: Icons are small, but can be easily selected and clicked using a mouse or trackpad. Files and folders can be easily accessed by selecting their icon.
Smartphone / Tablet HCI: Icons are larger to make them easier to tap with our fingers. To simplify the interface, icons are only used to represent apps – most other files are hidden.
Windows
Desktop / Laptop HCI: Apps run in resizeable windows which can be moved around the screen. This also enables the user to drag files and folders between windows, and to run several apps simultaneously on the same screen.
Smartphone / Tablet HCI: Due to limited screen size, apps usually run full screen. This also prevents users from running too many apps at the same time, which could affect system performance.
Input Methods
Desktop / Laptop HCI: Input is usually by a combination of keyboard and mouse. These allow operations, such as moving files or entering complex commands, to be completed easily and accurately.
Smartphone / Tablet HCI: The primary method of input is through the touchscreen. Swiping and flicking gestures enable fast and intuitive interaction without the need to connect a bulky keyboard or mouse to your phone.
Digital Platforms
You are required to know the design considerations for four digital platforms: websites, databases, mobile apps, and spreadsheets.
Websites
Databases
Mobile Apps
Spreadsheets
Websites
Purpose:
- To share information, promote services, or enable interaction
- Examples: shopping, booking, news, communication
HCI Design Considerations:
- Easy navigation (menus, links)
- Responsive design for different devices
- Accessibility (contrast, font size)
- Clear layout and visual hierarchy
Databases
Purpose:
- To store, manage, and retrieve structured data, often through forms or search queries
- Examples: login screens, customer information systems
HCI Design Considerations:
- Simple, logical form layout
- Use of drop-downs, radio buttons, and validation
- Clear feedback and error messages
- Secure login and data protection
Mobile Apps
Purpose:
- To provide targeted, interactive services on mobile devices
- Examples: games, social media, communication apps
HCI Design Considerations:
- Touch-friendly controls (large buttons, swipes)
- Minimalist design due to small screen
- Consistent with OS (iOS/Android) look and feel
Spreadsheets
Purpose:
- To organise and process data using formulas, charts, and calculations—often for budgeting, analysis, or records
- Example: Microsoft Excel
HCI Design Considerations:
- Grid-based layout with clear rows and columns
- Use of icons, tooltips, and formatting controls
- Easy-to-read input and formula areas
- Error checking and cell validation tools
- Consistent with OS (Windows/MacOS) look and feel