1. For use in combination with an electrically-operated prosthetic appliance for replacing a missing limb, a control circuit responsive to input signals supplied thereto for operating said appliance and a set of at least two electrodes adapted to receive electromyographic (EMG) signals from the stump of the missing limb when fastened thereto, the subcombination for processing said EMG signal preparatory to delivering same to said control circuit which comprises: data processing means for analyzing the EMG signal so as to reduce it to a near minimum number of linear time series model parameters which are effective to differentiate each of several functions of the missing limb from all other functions thereof, data acquisition means for collecting and storing historical data produced by the amputee at the electrodes relative to the maximum and minimum values of said linear time series model parameters for each limb function to be performed by the prosthesis, comparison measuring means for repeatedly sampling current data on said linear times series model parameters produced by the amputee at the electrodes and comparing said current data with a set of predetermined values therefor chosen on the basis of said historical data, and means responsive to the comparison measuring means operative during each sampling interval to deliver one or more output signals to the control circuit effective to initiate or continue actuation of only that function or those functions of the prosthesis wherein the sampled data falls within the set of unique values chosen for a particular function.