A memory module socket disposed on a principal surface of a mainboard, and adapted to mechanically receive and electrically connect a memory module with a mainboard, the memory module socket including a first unit socket having a plurality of first socket pins adapted to electrically connect a first connector disposed on an edge of the memory module, and a second unit socket having a plurality of second socket pins adapted to electrically connect to a second connector disposed on the memory module orthogonal to the first connector, wherein the memory module as installed in the memory module socket is parallel to the principal surface of the mainboard.