[zvr]

Decades ago I worked on an ATM that "recycled" money. It did not only had the usual boxes of banknotes that were filled by the bank, but it also accepted deposits. Usually deposits are put in an envelope by the client and an envelope is stored in the machine; this makes reconciliation easy, since a bank employee opens the envelope, counts the money, and confirms the deposit transaction.

But on this ATM, people would deposit their banknotes directly. The machine would recognize and count them, crediting the correct amount to the person's account. And later, when someone wanted to get money out of the ATM, the machine would use these exact banknotes!

It was an innovative design, which saved the bank a lot of money (in ATM-caring trips) and provided people with a real service, since they could use the ATM longer, instead of getting error messages that it was out of cash (well, it never said that it was something more generic like "problem in operation").

As one can imagine, it was an interesting challenge designing the software and thinking of all the tests covering what might go wrong...

[TRiG_Ireland]

I've never seen an ATM which took money in envelopes. Does it just take on trust the amount until it's verified by an employee counting it later?