Operating Systems and Digital Platforms

What Does an Operating System Do?

Before you can design or use an HCI, something must manage the hardware, run the software and provide the interface layer between the user and the machine. That something is the operating system (OS). Every digital device — from a smartphone in your pocket to a server in a data centre — runs an operating system. The OS performs three core jobs: it manages hardware resources (telling the processor, RAM and storage when and how to be used), it runs software applications, and it presents the HCI through which users interact with the device.

This topic is not covered in the coursework units — which means students who revise only from their NEA projects often miss it entirely. The exam asks you to name specific operating systems, describe their key characteristics and explain how the OS choice shapes the HCI design.

Desktop and Laptop Operating Systems

Windows is the dominant desktop OS in most business and educational environments. Its HCI is built around a taskbar at the bottom of the screen, a Start menu for launching applications and a windowed interface where multiple apps run simultaneously in resizable panels. Designers building for Windows can expect users to interact via mouse and keyboard, and to expect familiar navigation patterns such as right-click context menus.

Apple macOS runs exclusively on Apple’s own hardware. Its HCI uses a Dock at the bottom of the screen, a persistent menu bar at the top and a design language emphasised in Apple’s Human Interface Guidelines. macOS designers target a user base that expects visually polished, consistent interfaces with smooth animations. Software compatibility is narrower than Windows but the hardware and software ecosystem is tightly controlled.

Linux (and Ubuntu) is open-source and free. Ubuntu is a widely used distribution designed to be accessible to non-technical users. Linux HCIs vary significantly: some use graphical desktops resembling Windows; others are primarily command-line interfaces used by developers and system administrators. Because Linux can be configured so freely, HCI designers targeting Linux environments must account for a wide range of possible interface configurations.

Unix is the historical foundation from which macOS evolved (via Apple's acquisition of NeXT, which was BSD-based). Linux is a separately written, Unix-inspired operating system — it is Unix-compatible but was not derived from Unix source code. Today it is found mainly in enterprise-grade server environments and academic institutions. Unix systems are typically operated via command-line interfaces, so they are not usually the target environment for consumer-facing HCI design — but the exam requires you to know it exists and its primary use context.

Chrome OS is Google’s operating system for Chromebook devices, popular in schools. It supports web apps and, on compatible devices, Android and Linux applications. Designers should consider responsive web design, native-app patterns and offline use.

Mobile Operating Systems

Apple iOS has a tightly controlled app ecosystem. App Store apps must pass Apple’s review process, although some regions allow alternative distribution. HCI design for iOS follows Apple’s Human Interface Guidelines closely: consistent navigation patterns, specific button sizes and placement conventions, and design expectations around gestures (swipe up to go home, long press for options). The closed ecosystem means fewer device variants to design for, but developers must follow Apple’s rules.

Android is open-source and used on devices from many different manufacturers. This makes it the most widely used mobile OS globally. However, it creates a design challenge: Android runs on devices with hugely varying screen sizes, processor speeds and display resolutions. A designer targeting Android must test across multiple device types and plan for responsive layouts that adapt to different dimensions. The Google Play Store distributes Android apps, but the approval process is less restrictive than Apple’s.

Digital Platforms

Operating systems run software — and the software environment the HCI is designed for is called the digital platform. The four digital platform types named in the specification are: database, mobile app, spreadsheet and website.

A database platform presents data in structured tables and forms. The HCI for a database typically includes search fields, data entry forms, filter controls and tabular displays. Users are often data professionals rather than general consumers. A mobile app is installed on a smartphone or tablet and uses the device’s touchscreen conventions. Its HCI must use large tap targets, limited navigation depth and mobile-specific interaction patterns. A spreadsheet platform (such as a desktop application or web-based tool) presents data in a grid of cells. HCI features include formula input, cell formatting and chart generation — designed for numeric analysis rather than casual browsing. A website runs in a browser and must be designed to work across different browsers, screen sizes and operating systems simultaneously. Responsive design — the ability to adapt the layout to different screen widths — is essential.