The System/3x family and RPG were designed for customers who were migrating off unit record equipment. Unit record equipment was "programmed" by wiring plug boa

The System/3x family and RPG were designed for customers who were migrating off unit record equipment. Unit record equipment was "programmed" by wiring plug boards, and the unit record machine would filter, transform, collate (etc.) each card in a stack of input cards by applying the rules specified by the wiring of the plug board. With the fixed formatting and "program cycle", RPG was intended as a sort of skeumorph for technicians who would have been trained to "program" unit record equipment on a wiring diagram. (Contrast the wiring schematic here: http://www.righto.com/2017/04/1950s-tax-preparation-plugboard.html http://www.righto.com/2017/04/1950s-tax-preparation-plugboar... with an RPG template here: https://www.richard-banks.org/2014/01/a-little-nostalgia-with-wang-vs-and-rpg.html https://www.richard-banks.org/2014/01/a-little-nostalgia-wit...)