A mainframe seismic system consisting of 50 major programs operating on an IBM mainframe were ported to a UNIX distributed processing system. The UNIX seismic system consisted of a network of high performance workstations with full UNIX operating characteristics. These workstations were connected using an Ethernet cable as shown in Figure 1. The IBM mainframe plus the seismic plotters were a node on the UNIX network during the porting of this software .