The Amptek PX4 is an interface between Amptek’s XR100 series of X-ray and gamma-ray detectors and a personal computer with data acquisition, control, and analysis software. The PX4 includes three major components: (1) a shaping amplifier, based on a state of the art, high performance, low power DP4 digital pulse processor, (2) a multichannel analyzer, and (3) power supplies. It replaces both the previous generation PX2 shaping amplifier and power supply and the separate MCA.