@temptoetiam @MaitreCrevettes @PastaThief Maybe you had a single-sided 5 1/4" floppy drive and you punched a second hole in your floppies to be able to use the backside by placing them rotated in your floppy drive.
I did that in 1982 or so.
Single sided, 34 tracks, single density were about 80 KByte capacity per side. I still have that drive in my cellar.
@temptoetiam @PastaThief obviously.
(Note that some knitting machine also ran on punch cards, so you can find such items in knitting tools on Etsy I guess, though they are probably different because you punch in the middle of the card, not only on the sides like this one or the "pince à tiercé")
My floppy of choice back in the day...when I could afford them.
You can make the flip side usable or, if you’re bad enough at it, both sides unusable.
http://www.catb.org/jargon/html/F/flippy.html
You could use a hole punch to make another write notch on the other side of a single-sided floppy, doubling your disk space (though at the time most drives could only read one side at a time).
Some disks were also shipped without a write notch at all, so that you couldn’t replace whatever was on them; a hole punch gave you a free reusable floppy!
@rk I used to own a square hole punch that had a spacer that aligned the floppy to the exact position for the hole. I was a hit at the BBS parties, let me tell ya.