There seems to be a few people who work with ATM software here at the moment, so perhaps one of you could answer a usability question that bugs me about ATMs:
- On entering my PIN and selecting the option to withdraw cash, I'm presented with a number of choices (e.g., €20, €50, €90, €200 etc.).
- I select €90 and wait the ~10-20 seconds for the ATM do do whatever it needs to do.
- I'm presented with a message telling me that the machine can only dispense multiples of €50, obviously because it's run out of smaller denominations.
- I'm returned to the 'amount-selection' screen and presented with the same set of choices, including the invalid ones.
I've now wasted almost a minute. Why doesn't the ATM just limit the list to what it's capable of dispensing? Is there some weird security consideration I'm missing?
The cash dispenser part is probably just a black box with a simple interface that accepts a message to "dispense some amount of cash" and that can respond "request failed" or "request succeeded". It may even have no concept of inventory and just knows that it tried to dispense X bills and it only got X-1 of them.
Yes, it could have a query function added, and yes the GUI could dynamically respond to that, but it's a bit of an edge case since the assumption is that the ATM is well stocked if it's got mixed bills.
- On entering my PIN and selecting the option to withdraw cash, I'm presented with a number of choices (e.g., €20, €50, €90, €200 etc.).
- I select €90 and wait the ~10-20 seconds for the ATM do do whatever it needs to do.
- I'm presented with a message telling me that the machine can only dispense multiples of €50, obviously because it's run out of smaller denominations.
- I'm returned to the 'amount-selection' screen and presented with the same set of choices, including the invalid ones.
I've now wasted almost a minute. Why doesn't the ATM just limit the list to what it's capable of dispensing? Is there some weird security consideration I'm missing?