Integrated Circuits Used 74LS90 Procedure Add IC 74LS90 into ICBase-2 (74LS90).Add IC 74LS90 into ICBase-3 (74LS90).Connect VCC Port to Pin-5 (VCC) of ICBase-2 (74LS90).Connect VCC Port to Pin-5 (VCC) of ICBase-3 (74LS90).