A semiconductor die having: a logic unit having a plurality of inputs/outputs; a plurality of pads whereby electrical connections can be made to the die; and a multiplexer arranged between the inputs/outputs and the pads, the multiplexer being operable in a first mode in which it maps a first number of the inputs/outputs to a first number of the pads with a first mean spacing between those pads, and a second mode in which it maps a second number of the inputs/outputs to a first number of the pads with a second mean spacing between those pads, wherein the first number is larger than the second number and the first spacing is smaller than the second spacing.