This paper presents the technical aspects of the initiative to upgrade non-safety control systems and perform control room modernizations at four nuclear units at three Duke Energy sites. To address Instrumentation & Control (I&C) obsolescence, a standard, non-safety, Distributed Control System (DCS) was selected, configured, and installed at the four units. This enables the migration of I&C functions from aging equipment to a modern, commercially available DCS (Honeywell Experion®). As plant I&C functions are migrated to the DCS over time, legacy Human Machine Interfaces in the control rooms are also upgraded. Over time, this will result in significant control room modernization. To lay the foundation for proper Human Factors Engineering (HFE) for this modernization, full integration of the DCS design into the plant simulators was accomplished at each site. In close coordination with the Turbine Control System (TCS) Upgrade Project at the same four units, fully functional glasstop simulators were also built at the three impacted sites. These were used for procedure development, operator training, and to support the NUREG-0711 based HFE Integrated System Validation (ISV) effort for the TCS Upgrade Project. The fleet-level HFE Program, developed for Duke Energy by the Idaho National Laboratory [1] and TCS ISV effort led by the Institute for Energy Technology, Norway [2] are the subject of separate, related papers.