The Counter and the Cab — Where the Screen Stands When Money Moves

The three fields before this were equipment. This one is a shop and a vehicle. Here the screen touches money.

What this seat constrains

The payment terminal at a counter has a certified path through it — the route the card details travel. Put anything on that route and certification starts over.

A vehicle's meter is a regulated instrument. Touch the arithmetic that makes the fare and it goes back for approval.

So this field imposes one condition. The screen has to sit outside that boundary.

One server, three screens

The ordering sample serves three screens from one server according to which device attached — kiosk, counter, kitchen. There is one menu, and one order appears at the three seats as the screen for choosing, the screen for taking, and the screen for making.

Payment goes across an adapter. What the screen receives is the outcome, and what it displays stops at what was ordered and how much.

Where the rounding happens

The scale-and-label sample writes this on the screen.

347 g on the pan, 2,980 won per 100 g. The exact figure is 10,340.6 won and the label prints 10,340 won. The rounding delta, −0.6 won, is printed on the screen beside it.

Compute the value in two places and that −0.6 splits. The label rounds to a unit a customer can pay; the ledger recomputes from the weight. Neither is wrong, yet each transaction is 4–5 won apart, and the gap only shows a day later once the totals accumulate.

The sample lets the rounding happen in one place only, and its verification re-adds the label amounts independently and reconciles them against the ledger total. It passes at a difference of zero.

The order in which the fare climbs

The taxi sample's run log keeps the sequence.

The meter starts on the frame where the door opens — the on-screen notice reads t=46.37s. The log then records the value three times.

The middle row is the character of this field. The distance is stopped at 0.65 km while the waiting time raises the fare.

The fare is made by that seat's own rule. The screen receives the value, shows it, and puts up the payment screen on arrival. The person presses one button.