A 1403 model N1 printer with the covers open. This printer averaged 1100 lines per minute and was extremely reliable. The covers were electric and opened automatically when it ran out of paper. Operators quickly learned not to leave coffee cups and other things on top. These printers used a "carriage control tape" which was a continuous loop of paper tape with holes punched in various columns, or "channels". Channel one was commonly used for "top of form", so a program could skip to channel one to quickly get to the top of the next page. Skipping to a channel that had no punch could empty a box of paper at an amazing speed.