US Patent 7206978 Error detection in a circuit module

A circuit module has a module board and a plurality of circuit chips that are arranged on the module board. A module main bus having a plurality of lines of the circuit module branches into a plurality of sub-buses having a plurality of lines. Each of the sub-buses is connected to one of the circuit chips. Each circuit chip has an indication signal generating unit for providing an indication signal based on a combination of the signals received on the plurality of lines of the sub-bus connected to the respective circuit chip, and an indication signal output for outputting the indication signal.