Apparatus for preventing transferring noise of digital signal

An apparatus for preventing transferring noise of a digital signal, comprising:

• a signal output circuit which outputs first data as a relatively high potential signal and second data as a relatively low potential signal respectively to a signal line;
• a bus constituted by a plurality of signal lines including said signal line which transfers the signal outputted from said signal output circuit, and a signal input circuit which inputs the relatively high potential signal as the first data and the relatively low potential signal as the second data respectively from said signal line;
• wherein said signal output circuit has inverted signal output means for outputting a signal whose potential represents the second data when the data which is to be outputted originally is the first data, and outputting a signal whose potential represents the first data when the data which is to be outputted originally is the second data,
• said bus has an inverted signal line for transferring an inverted signal outputted from said inverted signal output means, and
• said signal input circuit has noise-transfer preventing means for, when the potential signals representing the different data are transferred respectively from said signal line and said inverted signal line, outputting a signal whose potential represents data transferred from said signal line, and when the potential signals representing the same data are transferred from said signal line and said inverted signal line, outputting the signal, which has been outputted before that state, as it is.