Dropped cards: Columns 72 - 80 were for sequence numbers ... you wrote your program and jcl on coding sheets and sent the sheets to keypunching. The 029 was just for editing. That way, when you dropped a box, you just added an option to sort by seqno before compilation. Eventually, you would just get the whole deck repunched and recycled the mixed-up deck.

Photo courtesy wikipedia.

Games - you sent in a deck with your move, and then got a printout with the computer's move. Repeat as necessary.