System for enabling circuit board surface-slot-edge connections. A main board includes a slot through its surfaces. At least one edge of the slot includes electrical contacts to the main board. An auxiliary board includes a connector component mounted on a surface that opposes a surface of the main board. When the connector component is aligned with the slot, the connector component can protrude vertically through the slot, in addition to moving laterally towards an edge of the slot. Electrical contacts on the edge of the slot can engage with electrical contacts in the connector component. This enables two boards to be arranged closely, without extending the main surface in an orthogonal or lateral direction, using a secure connection provided by a connector attached to the auxiliary board, rather than the main board.