Abstract: The microprocessor production instrumentation package (MPIP) is an electronic testing device used in railway vehicles operated on a test track to insure that the vehicles meet rigid operational specifications. The testing device provides vehicle data regarding axle speed, brake pressure, motor armature and field currents, acceleration, etc., in a time-saving manner. The self-calibrating MPIP provides permanent data curves from an oscillograph and a paper tape print-out of the vehicle data as it is generated. The testing device is powered by the vehicle's DC supply and is small enough to be hand-carried onto the vehicle.