80-column cards were used.
Cards were punched (and verified - ie punched again to confirm that both operators punched the same thing) in the "punch-room" - a dangerous place to enter - serried ranks of fearsome girls, who stared at you when you entered, without a hint of a pause in the punching rhythm! The punch-room was ruled by Mary - tiny, but definitely in charge, and not to be trifled with. Incidentally, Mary's sister Elsie was secretary to the boss, so the two of them made a very powerful axis!!
For one-off use, there was a manual card punch available in the computer room. The punch had 12 keys - for the twelve vertical hole-positions on the card. This was a very slow process. To punch a number was fine - hit one of the keys marked 0-9. Letters were more difficult - you need to press one of the A or B keys at the same time as a number key, so as to punch the two-hole code. Special characters were even more complex, as they needed THREE holes, so you had to press three keys at once. Amazing how fast some people became with practice!
We knew all about chads long before Jeb Bush revived their fame!
Indeed, where a single character error was found in a card, it could be corrected by sticking a chad back in the offending hole and burnishing it with the thumbnail to make it stick! I remember one occasion where a program didn't work - the alert operator spotted a loose chad on the console desk and pointed it out to the programmer, who knew that one card had been repaired, and was able to return the escaped chad to its rightful place and continue!! Not good practice.