I don't mean "oh you can play old games on your phone", everyone knows that. I mean playing old games using an actual floppy disk drive.
This video by LGR shows how its done, using a phone's USB port to hook up a drive, get it working and read by the phone and then allowing you to play ancient PC games like, in this case, Commander Keen.
Obviously this is a guide for Android phones. This is... not really an iPhone kinda deal.