Abstract: A personal computer system has an I/O channel and a memory channel with a main logic board incorporating both the I/O channel and the memory channel. The computer has eight (8) expansion slots including a dual-purpose expansion slot for providing space for selective connections of I/O devices through the use of full-length logic cards or half-length logic cards being inserted into edge connectors, High speed memory, including memory control, is mounted on the main logic board and expansion memory, controlled by the memory control is mounted on a printed circuit card that is connected to the memory channel in position within the dual-purpose expansion slot, occupying approximately one-half of that slot, thereby enabling the dual-purpose expansion slot to encompass both the expansion memory and a half-length logic card. In another embodiment, the half-length logic card and the memory card within the dual-purpose expansion slot are integrated into a single logic/memory card.