The present invention provides an apparatus for evolving a 5 volt V.sub.cc signaling environment to a 3.3 volt V.sub.cc signaling environment. A 5 volt bus connector and a 3.3 volt bus connector are provided with a key disposed at different locations on the respective connectors. A 5 volt circuit board, populated with components compatible with 5 volt signaling environment, includes a mating key designed to receive the key of the 5 volt connector. A 3.3 volt circuit board, populated with components compatible with 3.3 volt signaling environment, includes a mating key designed to receive the key of the 3.3 volt connector. Accordingly, the 5 volt circuit board may only be inserted into the 5 volt connector, and the 3.3 volt circuit board may only be inserted into the 3.3 volt connector. A universal dual voltage board is provided which may be populated with components compatible with either 5 volt or 3.3 volt signaling environment. The universal dual voltage board includes mating keys designed to receive both the keys for the 5 and 3.3 volt circuit, and as such, may be inserted into either the 5 or 3.3 volt connector. The universal dual voltage board also includes special I/O power metal contacts which mate with the special I/O power pins in either the 5 or 3.3 volt connector so that the universal dual voltage can be adapted to the signaling environment of the connector. A method is also provided to evolve a 5 volt V.sub.cc bus into a 3.3 volt V.sub.cc bus without rendering the existing 5 volt V.sub.cc bus systems incompatible.