DRM before 1990 typically involved non-standard floppy disk formats that a home computer could not duplicate. You can read about one such scheme here: http://d

DRM before 1990 typically involved non-standard floppy disk formats that a home computer could not duplicate. You can read about one such scheme here: http://dmweb.free.fr/?q=node/210 http://dmweb.free.fr/?q=node/210