Methods and apparatus are described for pinning out multiple memory devices using shared conductors therebetween and providing multiple chip select signals to indicate to which of the memory devices address signals on the shared conductors apply. In the case of a clamshell configuration with a top memory device having a corresponding bottom memory device and shared vias coupled therebetween, sharing two address signals for each shared via in this manner reduces the total number of vias used, thereby reducing routing congestion and enabling the addition of ground vias around the shared vias to reduce crosstalk for the address signals.