I replaced an old AS400 system from the 70s as one of my first gigs. It was 50k lines of incomprehensible RPG code. I would often have to print out the code, st

I replaced an old AS400 system from the 70s as one of my first gigs. It was 50k lines of incomprehensible RPG code. I would often have to print out the code, steal a conference room, lay out all the pages, and go to town with a bunch of highlighters to tell what the hell was going on. On the plus side, the code still had comments for the punchcard numbers, so it was pretty easy to keep the pages in order :)