eli5 How did Credit/Debit Cards work before Chip & Pin Machines?

Question

eli5 How did Credit/Debit Cards work before Chip & Pin Machines?

In: 64

Answer 1

There was a book of known bad card numbers and you could call an 800 number to get an Auth (or at least check if card was bad). Later with modems the register would call. This was in very early 1980’s.