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Can this be right?  Am I missing something?

August 23, 2010

A professor asked to borrow a couple punch cards to pass around in class.  I recently saw an ad for a 1tb drive for eighty bucks, and got to thinking; how high of a stack of punch cards is that?

1,099,511,627,776 bytes, or 1tb
divided by 80 bytes per card =
13,743,895,347 punch cards, times .007 inches, the thickness of a punch card =
96,207,267 inches, divided by 12 inches per foot =
8,017,272 feet, divided by 5,280 feet in a mile =
1,518 mile-high stack of punch cards to equal 1tb.

Really?  It just sounds impossible, like I missed a bunch of decimal points somewhere, or made some massive error in logic.

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  1. Ray
    August 23, 2010 at 16:07 | #1

    ‘terabytes’ and ‘gigabytes’ are terms that these days are bandied around with pretty much zero appreciation for just how much data they represent. But of course you already know that.

    Having spent many hours of my life poring over paper dumps of mainframe systems, I have a better feeling than most of how large even a lowly megabyte is, let alone these other monsters. I also still have a stack of blank punch cards, which are really handy for keeping notes and lists.

    But your calculations do bring it into some sort of perspective – so that the 2.5TB in my tiny backup server, if converted to punched cards, would make a pile that would reach from here in New York all the way to the Pacific Ocean. That’s a lot of chad!

  2. Ray
    August 23, 2010 at 16:31 | #2

    Correction: way further than merely to the Pacific. The pile would stretch from here to the Bering Straits.

  3. August 24, 2010 at 09:31 | #3

    So that means there are 658 MB of ‘mile-high-club’ porn available?

  4. David Evans
    September 11, 2010 at 06:14 | #4

    It’s easier if you have the good fortune to live in metric Britain. Multiply the number of cards by the thickness of a card, 0.1778 mm, to get 2443664592.6966 mm. There are 10^6 mm in a km, so shift the decimal point 6 places to get 2443.664 km. Then (if you must) divide by 1.609 to get 1519 miles

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