Whem my dad worked for Hughes Aircraft back in the 60's, he would bring home used punchcards for us kids to play with.
Posted by Alan at 6:05 am (PDT) on Wed September 11, 2013
"Do not bend, fold, staple, or mutilate."
Posted by Max at 4:45 am (PDT) on Mon August 17, 2009
Maybe the 70 byte print on an 80 column card started out as a spec for a particular application. Some programs used the last few columns for comments. I think I used a school computer somewhere that required some sort of ID punched on each card.
Whatever it was first intended for, only the first 70 columns mattered in that applicatoin. My hypothesis is that it later became an imperfect solution for others uses in which it was convenient to have the cards printed.
Most of the school keypunch machines had such dry ribbons that there was not much use in printing. I'd get a verbatim printout of my deck of cards if I needed it for debugging/editing.
When I started doing this stuff for money, someone else somewhere else punched the cards before cards gave way to more modern ways of writing files.
Although I worked with Sperry UNIVAC mainframes, all our keypunches were IBM 026's or 029's. As I recall, they had a switch for printing human-readable (well, given your comment, perhaps I should say easily human-readable) text at the top of each column as it was punched.
However, I don't believe that our mainframe's automatic card punch printed anything, and we had to use an IBM card interpreter to add the printing if it was needed. Unfortunately, the interpreter didn't print a full 80 columns, but rather about 70, each a bit wider than a column of punched holes. Thus, the print wouldn't line up with the punched columns! Who thought up that arrangement??
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Whatever it was first intended for, only the first 70 columns mattered in that applicatoin. My hypothesis is that it later became an imperfect solution for others uses in which it was convenient to have the cards printed.
Most of the school keypunch machines had such dry ribbons that there was not much use in printing. I'd get a verbatim printout of my deck of cards if I needed it for debugging/editing.
When I started doing this stuff for money, someone else somewhere else punched the cards before cards gave way to more modern ways of writing files.
However, I don't believe that our mainframe's automatic card punch printed anything, and we had to use an IBM card interpreter to add the printing if it was needed. Unfortunately, the interpreter didn't print a full 80 columns, but rather about 70, each a bit wider than a column of punched holes. Thus, the print wouldn't line up with the punched columns! Who thought up that arrangement??
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