[en] This article reports on a study undertaken to find a cost- and engineering-effective design for an on-line computer system for a pressurized water reactor (PWR) nuclear power generating plant. Two basic design approaches were analyzed: CBCMS, the computer-based central multiplexing system, has a central computer and a central multiplexer with all field inputs and outputs wired directly to the multiplexer. The scan, data processing and man/machine interface functions are executed by the central computer. This system configuration requires a large amount of cable and cable throughways, as well as complete functional centralization. CBRMS, the computer-based remote multiplexing system, employs units that are located throughout the plant. Each unit, a microprocessor system executes the scan, communicates with the central computer and does some front-end processing. Communication via serial twisted-pair cables decreases the cable runs and throughways