yes. the printers had 132 columns. you sent a buffer of 133 chars, the first being carriage control. blank was line feed, i forget what was page-eject/form-feed

yes. the printers had 132 columns. you sent a buffer of 133 chars, the first being carriage control. blank was line feed, i forget what was page-eject/form-feed (1?? memory fuzzy). + was overprint. As a student, I had a part-time job as an I/O clerk. (feed the card reader, file printouts). We disabled overprint on student jobs because it caused a lot of headaches from bugs. Form feed in an infinite loop was enough hassle. The original IBM printer did not document + for overprint, it was the result of a logic optimization in the controller and someone discovered it. So IBM installed a field change order that disabled that function, but included a switch that for an additional monthly fee would upgrade your printer to a model that supported it. The automatic openning of the lid at the end of a box of paper destroyed coffee cups on a regular basis.