While attending college, I worked as a mainframe operator in the evenings at a data center for a bank. There are parts of the financial system which are most d

While attending college, I worked as a mainframe operator in the evenings at a data center for a bank. There are parts of the financial system which are most definitely not digital and not 'online' at all. For instance, each night I would have to dial in to a national server to download the transactions from ATM cards, then load those into the banks system. I don't know if that has changed, but that introduced a great deal of lag. The bank only operated on weekdays. And not on holidays. So anything done on those days didn't update the account information until the night after the next bank day. So if you went and withdrew money via ATM after 5PM or so (this is assuming the national system WAS online and realtime... I don't actually know that for a fact) on a Friday and there was a bank holiday on the following Monday, your account at the bank would not reflect that until Tuesday evening (I worked in the evening, and it was my responsibility to do that). This was awhile ago, up until 2001, so things may have changed but I strongly doubt they have changed very significantly given that even then they were using an NCR mainframe which was literally the very last operational one of its kind (the owner of the 2nd to last one gave us theirs for free when they replaced it with a PC, so we got a DR site!). Their policy was to never change anything that cost a penny if it still functioned. When I left, the bank had been acquired by a larger bank and the plan was to move the smaller banks processing into the larger ones data center. I ran into one of my coworkers 5 or so years later and none of that had happened. Everything was still as it was.