Abstract: An apparatus for providing hitless by-pass switching for signal flow paths on a circuit board. The switches for establishing the by-pass path(s) are mounted adjacent to the connector into which the board is inserted. The circuit board has mounted thereon an apparatus which engages the by-pass switches in a manner so as to open the switches and maintain them open when the board is essentially fully inserted in the connector. Otherwise, the switches are closed. The signal flow paths on the board are conductive when the board is both fully and partially inserted in the connector. When the board is partially inserted in the connector, both the by-pass and circuit board paths are conductive.

Abstract: A mid-plane board for orthogonally interconnecting a first set of circuit boards to a second set of circuit boards. The mid-plane board has a first group of pins which project outwardly equally on both sides of the board. It has second and third groups of pins which project outwardly only on one or the other side of the mid-plane board, respectively. The circuit boards have edge connectors and the pins of the first, second and third groups are associated with the edge connectors in a manner such that the circuit boards of the first set are orthogonal to those of the second set when they are connected to the pins. An assembly for the mid-plane board and the circuit boards is also disclosed.