Why do computer punch cares never show two or more numbers punched one above the other?

Steve R September 30, 2013
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This will definately date me,but I’ve always been intrigued by why there never are two(or more)numbers punched one above another? they’re always staggered in the punches. Example;a card has five rows,lets say. Rows 1 and 2 are all 1’s,Rows 2 and 3 are all 2’s,Rows 4 and 5 are all 3’s. So Row one has the first 1 punched,then Row 2 will have the second 1 punched. Row 3 has the third 2 punched,Row 4 has the fourth 2 punched,Row 4 has the fifth 3 punched,and Row 5 has the sixth 3 punched. There are never any numbers punched directly below a number in any other row.

Why is-or was-that?

I hope I’ve explained this so you’ll understand. It’s just an FYI that’s always interested me.

Steve Rathbun

  1. Bill G
    September 30, 2013 at 3:30 pm

    You mean the IBM style 80 column punch cards? Like the ones that used to be in utility bills and such? Now and then I'd punch an extra hole in them when I sent them back :-)

    Those are also called Hollerith cards after the person inventing them. Several codings were used but in the most common IBM EBCDIC representation numeric digits were a single punch in a column but letters were two punches and some characters actually required three punches per column. I think a column with every position punched was used to ignore the column -- i.e. the keypunch operator made an error which he/she noticed so it told the card reader to skip that column and move on to the next.

    Yeah, you might be dating yourself but I used to work with them too!

    There's some more info here: http://en.wikipedia.org/wiki/Punched_card

  2. Oron J
    September 30, 2013 at 8:32 am

    Are you talking about old style punched cards? Your description does not match any punched card I've ever seen (which had 8 rows, and holes were most definitely arranged in combination within a column).