Punched Card

Before terminals were the default I/O device, computerz typically used punched cards (Hollerith). Here are a couple of links:

• punched card (Wikipedia)
• The IBM punched card

The 80 columns found on terminals came from the punched card. CRTs of the time that could display 80 columns clearly naturally display 24 lines (hence the default 80x24 terminal window).

Here is an image of a typical card: