Decommutator patchboard verifier

A system for automatically verifying the connections between terminals of a patchboard. The system includes a back plane having a plurality of plugs provided therein corresponding to the pins of the patchboard so that the patchboard can be plugged therein. A plurality of decoders are connected to the plugs of the back plane so that a signal can be sequentially applied to each plug of the back plane under control of a stepping register and a control circuit. A plurality of data selectors are also connected to the plugs of the back plane and under control of a second external register and said control circuit sequentially make connections between an output circuit and the plugs of the back plane so as to patch the signal applied to a respective plug through a patch connection to the output circuit. By making the above connections in a controlled manner, the precise locations of the patches on the patchboard can be identified and compared with previously stored information in a memory unit.