Re: How many IBM punch cards in 20 Giga Bytes of Data

I think I can make a guess right off the bat and say it's a pretty big room. My computer usage days began post-punch card, so I had to do a little bit of research on the subject for you.

For those who don't know, punch cards used to be used to input/output/store data. You can see some pictures of punch cards at the Punch Card Gallery. It appears that a standard punch card had 90 rows of 10 positions to punch a hole. Each hole basically represents a digital bit. Either it's there, or it's not. 0 or 1. So 90 x 10 = 900 bits per punch card. A byte is equal to 8 bits, so that's 112.5 bytes per punch card.

A gigabyte is equal to 1,073,741,824 bytes (that's 1024 x 1024 x 1024). So it would take 9,544,372 punch cards to make a gigabyte. To make your 20Gb hard drive, it would take over 190 million punch cards. That would take a long time to punch.

As far as how much room it would take, I'm going to have to make a guess here. If I assume that a punch card is about as thick as an average notecard, and a pack of 100 notecards is about an inch thick, then you would have a stack of punch cards 30 miles high! That is a big room!

Your Mad Scientist,
Mike Scannell