IBM's technology for the 70x0 and 14xx series of 1950s mainframe computers was Standard Modular System. PCBs had an edge connector, one sided, with 16 pads. The sockets were mounted on a backplane with wirewrap connections between sockets. Cables connecting to a backplane used a version of the PCB edge called a paddle card to insert into a socket.

IBM also used SMS to deliver power, usually to peripheral devices . It was a modified version of the card edge, combing some pairs of traces to carry more current. It also had a notch in the center of the card edge. The sockets into which these power paddle cards were inserted had a metal bar which prevented an ordinary paddle card, which would carry logic signals, from accidentally being plugged into the power socket. Only the power paddle cards could fit into the sockets.

As an example of use of power paddle connections, on the IBM 1130 computer, SMS power paddle cards were used to provide power to the 1053 console printer, the internal disk drive, the 1627 plotter, and the 1134 and 1055 paper tape devices.