 The Argus 400 used silicon transistors in a NOR-logic designed by Ferranti Wythenshawe called "MicroNOR II", with more "conventional" logic where 0 and +4.5 represented binary 1 and 0, respectively.The rest of the world however used 0 volts to represent 0 and + 2.4 (to 5) volts to represent 1.This was called NAND logic.