4 ms·
Which brings us to the question of why 80 columns became the standard for punch cards? All I can find is that 80 columns increased the information density over
by Mountain_Skies 3y ago
Which brings us to the question of why 80 columns became the standard for punch cards? All I can find is that 80 columns increased the information density over 45 column punch cards but nothing about why 80 was the standard instead of 60, 88, 132 or many other possibilities. Going to guess it was some kind of tradeoff between various physical limitations of machinery and tooling at the time but maybe those exact details have been lost to time.
- rep_lodsb 3y agoProbably because (tele)typewriters had similar line widths, 72 columns IIRC. That would leave 8 columns remaining on the card for the line number.
- Mountain_Skies 3y agoWhich moves us to the next turtle in the stack with the question of why teletypewriters used 72 columns?
- int_19h 3y agoIBM punch cards had 80 columns because that's how much they could cram onto the already-existing standard Hollerith punch card by making holes smaller and rectangular without making the cards too fragile. Said standard punch card size was 3.25 by 7.375 inches, which not coincidentally is exactly the size of a 1887 dollar bill. The reason why that size became so common is because it was used in the 1890 US census, which was the first widely publicized application that popularized the technology. And the reason why it matches the size of the dollar bill is because Hollerith could then reuse cash storage boxes used by the US Department of Treasury for cards. (http://www.columbia.edu/cu/computinghistory/census-tabulator.html http://www.columbia.edu/cu/computinghistory/census-tabulator...)
- deleted 3y ago[deleted]