Abstract: A generally plate-shaped adapter device has an inner edge portion with spaced bosses thereon that may be snapped into tooling holes in a printed circuit board which is smaller than the circuit board originally designed to be secured to mounting portions formed on a computer chassis wall. The in-place adapter device forms an outward edgewise extension of the smaller circuit board and has an outer edge portion positioned and configured to cooperate with the chassis board mounting structure in a manner permitting the reduced size printed circuit board to be operatively mounted on the chassis wall without modification of its board mounting structure.