A terminal has none of the affordances a phone gives you.
Touch accuracy is poor, glare is real, there is a person waiting behind you, and the user has no mental model of a back button.
Anything ambiguous does not become confusion. It becomes a queue.
Design for the queue, not the screen
The real measure of a terminal interface is how quickly the next person can start.
Bigger, slower and more literal than any other interface I have designed.
Every constraint pointed the same way: reduce what a screen asks, and make what it asks unmistakable.
One decision per screen
Never two questions at once, however related they seem.
Combining choices saves a screen and costs comprehension. At a terminal, comprehension is the scarce resource — the extra tap is nearly free by comparison.
Targets and contrast for the real environment
Sized for imprecise, gloved touches in direct sunlight.
Type contrast was set for outdoor glare rather than an office monitor, and targets were sized well beyond guideline minimums because the guideline assumes a phone in a steady hand.
Timeouts you can see and survive
The session never disappears silently.
Time limits are shown before they matter and are recoverable when they pass, which removes the most common cause of an abandoned transaction.
An interface that holds up under time pressure.
The common cash journeys were reduced to the fewest possible decisions, with each one legible in poor conditions. The design brief was never elegance — it was that nobody in the queue has to think.