Integrated Circuits Used 74LS20 Procedure Add IC 74LS20 into ICBase-3 (74LS20).Connect GND Port to Pin-7 (Ground) of ICBase-3 (74LS20).Connect VCC Port to Pin-20 (VCC) of ICBase-3 (74LS20).Connect Input-0 to Pin-1 (Input) of ICBase-3 (74LS20).