Abstract: A bus device, such as a memory board, is provided with a mother board and a daughter board mount at a predetermined distance above the surface of the mother board. The daughter board has integrated circuit components, such a memory chips, mounted on both of its sides. Means are provided for connecting the wires on the daughter board with those of the mother board and for connecting the wires on the mother board with the conductors of a system bus. In the preferred embodiment of the invention the distance at which the daughter board is mounted above the surface of the mother board is less than twice the maximum thickness of the electronic components mounted on the side of the memory board facing the mother board. The portion of the mother board under these components contains no electronic components itself. Instead, that portion of the mother board contains at least one ventilation opening to ventilate the components on the side of the daughter board that faces the mother board.