Abstract: A computer bus system is provided with at least two parallel bus lines and at least a first and a second connector, each connector including at least two bus terminals. Each is connected to a respective bus line, and at least one non-bus terminal is not connected to a bus line. The first connector is an image of the second connector, rotated through 180 degrees. This image rotation maps each bus terminal of the second connector to a respective bus terminal of the first connector, and maps a predetermined non-bus terminal of the second connector to a predetermined non-bus terminal of the first connector. The predetermined non-bus terminals of the two connectors are electrically connected. Also provided are circuit cards adapted to be used with such a bus, each card include switches that map the received signals according to the direction of the connectors. The overall arrangement allows staggered mounting of cards on the bus, shorter parallel bus lines, and more efficient cooling.