I used to have an ATM card with an 8-digit PIN. When entering the PIN, I noticed the screen would flash after the fourth digit. Subsequently, I discovered I act

I used to have an ATM card with an 8-digit PIN. When entering the PIN, I noticed the screen would flash after the fourth digit. Subsequently, I discovered I actually only needed to enter the first four. That continued until the bank got taken over by Bank of America in 2004. Suddenly, I needed to enter the whole PIN!