How do Debit/Credit cards know how much money they should have? Especially before the Internet.

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When I slidey debit card, how does the card reader know if there is money on it?

I understand nowadays that the card reader probably just asks over the Internet how much money the account has, but debit cards are older than the Internet, so what did they do back then?

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12 Answers

Anonymous 0 Comments

How far back do you want to go?

The short answer is they didn’t. The shop swiped the card on a mechanical machine, presented this to the bank and expected to be paid.

If there wasn’t the money/credit in your account to pay it, the bank settled it anyway and took it up with you, the customer.

Anonymous 0 Comments

My memory might be wrong but i vaguely remember having to call the credit card company during the pos and validating it that way. 

Or at the very least take imprint of the card and then run them through at the end of the day.