A personal computer system unit has a planar card upon which is mounted a processor card. The processor has mounted thereon those components, except for system memory, which are most likely to be replaced for a system upgrade. The processor card has a printed circuit board with printed circuits thereon that terminate along one edge at contacts. Two aligned edge connectors are mounted on the planar board. One connector has a key which engages a slot on the edge of the processor card to align the many contacts with contact arms. Two levers are mounted on the card and cooperate with frame elements to insert, extract and latch the processor card. Each element also has a guide to align the processor card for insertion into the edge connectors.