Abstract: A data processor comprises a multifrequency receiver formed together with a central processor on a semiconductor substrate. The multifrequency receiver produces digital data for identifying a tone wave included in a multifrequency analog signal or produces an identification result in accordance with the condition of signal issued by the central processor. The multifrequency receiver is thereby operative to deal with tone waves which are flexible in type and input analog signals which are flexible in their frequency band, and has increased latitude of choice for the operational characteristics and function such as the number of sampling periods of input analog signals and the discrimination accuracy.