The 4100 series of Boxcar Signal Averagers is made up of NIM standard modules plugged into a NIM bin and power supply. A system consists of boxcar averager module(s), ADC/display module(s), NIM frame and power supply, and optional software interconnected to produce a number of configurations, ranging from a simple single channel static gate system to a complex multi-channel system running under computer control. Systems can be upgraded by adding extra modules to increase the number of input channels.