The more I use my Apple IIc, the better I get at programming it. But there's one thing that I still don't understand. I still haven't figured out what the 80/40 key does. I know how to use the Keyboard key and what it does, but not so with the 80/40 key. I press it, type a bit, and nothing else happens.

What exactly does that 80/40 key do?

-Apostrophe