Interior shots of computer in operation at Revenu Canada Data Centre. MLS and CS of computer machine. CSs of push buttons "power", "print ready". MCS of paper data sheets coming out of machine. Various MCSs and CSs of parts of computer machine, of IBM-3420 magnetic tape, push buttons "select and ready", of control displays with words "printer", keyboard "output mode" instruction, of second including shots of lights blinking on and off.