Abstract: A process controller using a 16-bit microprocessor connected to a 10-bit analog to digital converter and a 10-bit digital to analog converter produces process correction signals having 16-bit accuracy. A raw sample of a process measurement signal is digitized to produce a first approximation of a process variable. The first approximation is stored and also reconverted to analog form as a processed analog sample. The processed analog sample is compared against the raw sample to generate and error signal corresponding to the difference. The error signal is amplified and digitized to produce a digitized refinement. The first approximation and the refinement are used to create first and second stage data words and a tabulated error value which are combined to produce enhanced digital data. Thereafter the enhanced digital data is used for calculation of a process correction command.