Around 2013, when I was just 13, on the computer at my grandparents place. I had to actually ask around and spend effort to find floppys since by then they were already obsolete, but my grandparents PC only had a floppy drive available. I used it to attempt to write an OS (I know I know, daunting task but I didnt know how much I didnt know). I got as far as writing the bootloader and got it to load and print Hello World, but no further.