Hardware Considerations for Designing Interfaces
Why Hardware Shapes Interface Design
Every HCI — whether it is a banking app on a phone, a self-checkout screen at a supermarket, or a fitness tracker on your wrist — runs on real hardware. The hardware choices available to a designer directly affect what the interface can look, feel and do. In the exam, questions on this topic often ask you to select suitable hardware for a given scenario or explain the impact of a hardware constraint on interface design. This lesson gives you the vocabulary and reasoning to answer those questions confidently.
Display Type
The type of display screen shapes what an HCI can show and how users interact with it. The four main display types are LCD (Liquid Crystal Display), OLED (Organic Light-Emitting Diode), e-ink, and capacitive touchscreen.
LCD screens are cost-effective and widely used on laptops, desktop monitors and retail tills. They require a backlight, which makes them less energy-efficient than OLED but suitable when cost matters. OLED screens produce richer colours and deeper blacks because each pixel lights itself. This makes them ideal for premium smartphone and TV interfaces where visual quality drives the user experience. E-ink screens use almost no power and are easy to read in bright sunlight — making them ideal for e-readers and bus-stop information displays that need long battery life and outdoor readability. Capacitive touchscreens allow finger-based interaction and are embedded in smartphones, self-service kiosks and point-of-sale terminals. The interface design must account for this: buttons need to be large enough to tap accurately, and hover states used on desktop menus become irrelevant.
Display Size
Screen size directly determines how much information can fit on the display at once and how the interface is laid out. A smartwatch screen (typically 1–2 inches) can display only a few lines of text or a single metric at a time — its HCI must use large icons, simple swipe gestures and minimal text. A smartphone screen (typically 5–7 inches) supports richer layouts but designers still favour mobile-first principles: large tap targets, scrollable content and simplified navigation. A laptop or desktop screen (13–34 inches) allows multi-column layouts, dense menus and complex dashboards that would be unreadable on smaller screens. A smartboard (interactive whiteboard, 55–86 inches) is designed for group use from a distance — text must be large enough to read across a classroom, and the interface should support large gestures rather than precise taps.
Display type and size together shape the entire HCI layout. A small OLED touchscreen (smartwatch) forces minimal-text, icon-based design; a large non-touch LCD monitor allows dense multi-column layouts. Matching display choice to context is a core design decision.
Memory (RAM) vs Storage — A Critical Distinction
This distinction is a common source of lost marks. Many students confuse memory and storage, or use the two words interchangeably. They are different.
RAM (Random Access Memory) is temporary. It holds whatever the processor is actively working with at this moment — the running app, the open browser tabs, the data being processed. When you switch the device off, RAM is wiped completely. More RAM means the device can keep more things open and running simultaneously without slowing down. For HCI design, insufficient RAM means sluggish animations, delayed responses when typing, and apps crashing when multitasking. A banking app with smooth transitions and real-time balance updates needs sufficient RAM to function as designed.
Storage (on a hard drive, SSD or flash memory) is permanent. It holds files, apps and the operating system even when the device is switched off. More storage means more apps and files can be saved on the device. For HCI design, storage capacity affects how many features an app can install locally versus requiring an internet connection to stream. It does not affect the speed of the running interface directly — that is RAM’s role.
Many students write about “memory” when they mean storage, and vice versa. A question such as “Explain how RAM affects the performance of an HCI” requires you to say that RAM is temporary working memory for actively running processes, and that insufficient RAM causes slowdowns and crashes during use. Saying “more memory means more files can be saved” scores zero — that describes storage, not RAM.
Use this quick test: if data disappears when you turn the device off, it is RAM. If data is still there after switching off and on, it is storage. The exam will give you a scenario (e.g. a self-service kiosk) and ask you to explain the impact of RAM or storage — apply this distinction directly to the scenario.
RAM is temporary working memory — it holds actively running data and is wiped on shutdown. Storage is permanent — it holds files and apps between sessions. RAM affects interface speed and responsiveness; storage affects how much can be saved locally on the device.
Processing Power
The processor (CPU) executes the instructions that make an HCI function. Processing power determines how quickly the device can carry out calculations, render graphics and respond to user input. An interface that runs on a low-powered processor — such as an embedded system in a washing machine — must be simple and lightweight: minimal graphics, no animations, limited options. A high-powered desktop processor can run complex data dashboards with real-time charts, animated transitions and multiple simultaneous background processes.
When a question gives you a scenario — “a hospital reception kiosk” or “a portable stock-checking device for a warehouse” — work through each hardware consideration in turn. For display: what screen size does the context require? Does the user interact by touch or indirectly? For RAM: does the HCI need to keep multiple processes running at once, or is it a single-purpose tool? For storage: does it need to store data locally, or does it connect to a network database? For processing power: does the interface need real-time updates, animations or heavy calculations?
A hospital reception kiosk might need a large capacitive touchscreen (accessible to users of varying abilities), moderate RAM (running a booking system and checking in patients simultaneously) and modest local storage (it connects to the hospital’s main server rather than storing records locally). A wearable fitness tracker needs a small OLED touchscreen, minimal RAM (it only tracks one or two metrics) and very low processing power — because everything must fit within a tiny battery budget.