Once the stroke signals are captured and digitized, the balance of the analysis and plotting is accomplished by the computer using an algorithm initially written in Microsoft Quick Basic Version 4.5. The program may be downloaded as a stand-alone executable file together with some text files that contain the values of user-adjustable parameters.  This version of the program is best run under DOS; it may be run in a DOS window under Windows 3.1, 95 or 98 but not Windows NT.  A stand-alone Visual Basic 5.0 version of the program, written by David Mazeroski when he was a graduate student at Penn State, is used to produce the current lightning locations estimated by the GP-1 system installed at Penn State; the program runs under Windows NT and is an implementation of the algorithm he developed for his MS Thesis.