Day 6 - Punch Cards

The first thing you have to do when reading a punch card is understand that each column represents a character.

The top two rows are referred to as 12 and 11, with 12 on the top.

If there is only one hole per column the character it has punched out is what is represented. For example if the number 2 is punched it represents 2.

If two holes are punched in a column it generally represents a letter. For example if 12 (the top row) and 5 are punched in a column that represents the letter E. If 11 and 2 are punched it's the letter K.

If there are more than two holes or there are two and one of the top three rows is not punched it generally represents a character other than a number or letter.

See this Wikipedia page for a chart to read letters and numbers off a card.

You can see on this punch card that in row 3 12 & 7 are punched representing the letter G. Row three has 12 & 1 punched representing the letter A.