Abstract: An interconnection assembly for connecting a unit under test to a testing unit including a plurality of spaced parallel circuit cards, the interconnection row assembly comprising of connector terminals adjacent the outer edges of each circuit card, an interface test adapter unit containing signal relaying circuitry for relaying the appropriate signals back and forth between the test unit and the unit under test, the interface unit having connectors for connection to the unit under test, and an outer face carrying connector terminals for connection to respective connector terminals on the circuit cards. A coupling mechanism releasably couples the units together with the outer face of the adapter unit facing the outer edges of the circuit cards.